Automated coastal flooding monitoring network and warning system feasibility analysis and design recommendations

[From the U.S. Government Printing Office, www.gpo.gov]

Appendix M

AUTOMATED COASTAL FLOOD
MONITORING NETWORK AND
WARNING SYSTEM

Feasibility Analysis
and
Design Recommendations

April 19W

IMP I I ro
QUO - al L

,nwa@

Prepared For:

CONNECTICUT DEPARTMENT

OF ENVIRONMENTAL PROTECTION

NATURAL RESOURCES CENTER
,7

Prepared By:

L.R. JOHNSTON ASSOCIATES

low
Westport, CT

B
1
9.2
-3
A88
1986

COVER PHOTOGRAPH: Clinton, Connecticut, September 27, 1985
during Hurricane Gloria.
Taken by Howard Sternberg, Connecticut
Department of Environmental Protection,
Natural Resources Center

AUTOMATED COASTAL FLOOD
MONITORING NETWORK AND
WARNING SYSTEM

Feasibility Analysis
and
Design Recommendations

April 1986

Pro0ared For:

CONNECTICUT DEPARTMENT

OF ENVIRONMENTAL PROTECTION

NATURAL RESOURCES CENTER

Prepar*d By:

L.R. JOHNSTON ASSOCIATES

W*stport, CT

ABSTRACT

This study was initiated by a Connecticut interagency Committe6 on Automated
Flood Warning to: (1) develop specifications for establishing an automated coastal
flood monitoring network which would be compatible with the existing statewide
automated riverine flood warning system; and (2) evaluate the feasibility of establishing
a State, coastal flood forecast and warning system.

There are currently five automated gages in operation along the Connecticut
coast that measure and record tide and storm surge levels. At present, data from
only one of these gages (Bridgeport) is used as input into the National Weather
Service's (NWS) forecasts and warnings. There are no automated wave gages or
other long-term measurements of waves along'the Connecticut coast.

All coastal flood forecasts and warnings are provided by the NWS, and most of
these are based -on meteorological data from large scale weather systems -and
specific storms (such as hurricanes). NWS has developed a state-of-the-art numerical
model for forecasting storm surge during hurricanes and tropical storms, and this
model has recently been applied in Long Island Sound. In contrast, NWS techniques
for forecasting wave heights and storm surge in Long Island Sound during extratropical
storms are based on limited data and simple statistical models. NWS forecasts and
warnings usually are not site specific,, and may apply to the entire Connecticut
coast, to all of Long Island Sound, or to a large subarea such as eastern Long
Island Sound or western. Connecticut.

While it is technically feasible for the State of Connecticut to develop its own
models for wave and extratropical, storm surge forecasts, such an approach would
be expensive and duplicate NWS responsibilities. This report recommends that the
State work with and encourage NWS to upgrade its forecast techniques for wave
heights and extratropical storm surge. It also recommends that the State supplement
NWS regional forecast data with real-time, site specific storm surge and wave
collected data through a network of automated coastal gages.

A low cost network of automated, real-time gages to measure tides and storm
surge could be deployed that would be compatible with the existing automated
riverine flood warning system. Adding wave measurement capability to the network
would significantly increase the cost of the system. The addition of wave data
also would require some compromi se in either the compatibility of the coastal
monitoring network with the existing riverine system or the type of wave data
collected. Further work is needed.to detail the specific system design if wave
data is to be collected as part of the coastal monitoring network.

A series of automated tide and storm surge gages at five permanent s ites is
recommended, along with two additional "roving" gages that can be used to correlate
data at many other coastal locations with data collected at one or more of the
permanent sites. Three of the permanent gage locations and the two "roving"
gages could be used for wave measu,rements.
Development of the coastal monitoring network can improve'NWS coastal forecasts
and warnings, provide State and local emergency. management personnel, with
needed site specific data on actual storm surge and wave conditions, and benefit
other potential users such as coastal researchers and recreational and commercial
boaters.

CONTENTS

ABSTRACT
CONTENTS v
LIST OF ILLUSTRATIONS vii
ACKNOWLEDGEMENTS ix.
1.0 INTRODUCTION AND SUMMARY

1.1 INTRODUCTION 1-1
1.2 METHODS 1-2
1.3 FINDINGS 1-3
1.3.1 Existing Tide, Storm Surge and Wave Measurements 1-3
1.3.2 NWS Storm Surge and Wave Height Forecast and 1-4
Warning Procedures
1.3.3 Connecticut Coastal Flood* Warning Procedures 1-4
1.3.4 Available and Emerging Technology 1-5
1.3.5 Potential Uses of Data from Monito ring,, Network 1-7
1.3.6 Costs and Benefits 1-7
1.4 CONCLUSIONS AND RECOMMENDATIONS
1-10
1.4.1 Conclusions 1-10
1.4.2 Recommendations 1 13
1.5 RECOMMENDED MONITORING NETWORKS 1-14
1.5.1 Number: and Location of Gages 1-14
1.5.2 Optional Monitoring Network Designs 1-14
2.0 TIDES"AND TIDAL FLOODING IN LONG ISLAND SOUND

2.1 TIDAL DATUMS 2-4
TIDAL VARIATION IN LONG ISLAND SOUND 2-3
2.3 RELATIVE SEA LEVEL RISE 2-4
2.4 TIDE, STORM SURGE, AND WAVE CHARACTERISTICS IN LONG ISLAND 2-9
SOUND
2.4.1 Waves 2-9
2.4.2 Tides and Storm Surge 2-11
2.5 COASTAL. FLOODING IN CONNECTICUT 2-20
2.5.1 Hurricanes and Tropical Storms (Tropical Cycldnes), 2-22
2.5.2 Extratropical Storms 2-28
2.5.3 Mapping of Coastal Floodplains 2-30.
2.5.4 Flood Damages 2-31

3.0 FLOOD FORECASTS, AND WARNINGS IN CONNECTICUT

@3.1 RIVERINE FLOOD FORECASTS'AND WARNINGS 3-1
3.1.1 National Weather Service ALERT Systems 3-1
3.1.2 Connecticut Automated, Flood, Warning System 3-3
3.2 COASTAL FORECASTS AND WARNINGS FOR'CONNECTICUT AND LONG 3-4
ISLAND SOUND
3.2*1 NWS Procedures 3-4
3.2.2 State of Connecticut Procedures 3-10
3.2.3 Municipal Procedures 3-10

CONTENTS (Contd)

4.0: REVIEW OF AVAILABLE TECHNOLOGY AND PROGRAMS

4.1 STORM SURGE AND WAVE MODELS 4-1
4.1.1 Storm Surge Models 4-1
4.1.2 Wave Forecasting/Hindeasting Models 4-7
4.2 INSTRUMENTATION 4-8
4.2.1 Tide and Storm Surge Measurements 4-9
4.2.2 Wave Measurements 4-14
4.2.3 Meteorological Measurements 4-17
4.2.4 Data Transmission, and Processing 4-17
4.3' C0&rAL M0NrI`OR[NG, FORBCAST AND WARNING PROGRAMS 4-18
4.3.1 Federal Programs Activities 4-19
4.3.2 Real-Time Monitoring Networks 4-23
4.3.3 Long Island Sound Water Quality Program 4-31

5.0: FLOOD MONITORING NETWORK DESIGNS

5.1 DESIGN CRITERIA 5-1
5.2 NUMBER AND LOCATION OF GAGES 5-2
5.2.1 Tides and Storm Surge 5-2
5.2.2 Waves 5-3
5.3 ALTERNATIVE NETWORK DESIGNS 5-5
5.3.1 Cautions on Cost Estimates 5-6
5.3.2 Tide and Storm Surge Measurements: ASERT Compatible Network 5-6
5.3.3 Tide, Storm Surge and Wave Measuremenst: ASERT Compatible 5-14
5.3.4 Tide, Storm Surge and Wave Measurements% Two Networks 5-19
5.3.5 Tide, Storm Surge and Wave Measurements: Independent from
ASERT 5-25
5.4 IMPLEMENTATION OF MONITORING NETWORK 5-24
5.4.1 Establishment of Gage Stations 5-24
5.4.2 Getting Information to Users 5-25
5.5 MAIN]rENANCEPFCGRAM 5-26
5.5.1 Maintenance Program 5-27
5.5.2 Maintenance Schedule 5-29
5.5.3 Maintenance Costs 5-31

6.0 CONCLUSIONS AND RECOMMENDATIONS

6.1 EXISTING MONITORING, FORE)CAST AND WARNING SMUM 6-1
6.1.1 Planned Improvements to Existing Technology and Programs 6-1
6.1.2 Opportunities to Further Enhance Existing Programs 6-2
6.1.3 Achievement of State Objectives Through Existing Programs 6-3
6.2 NEW PROGRAMS AND ADDITIONAL IMPROVEMENTS TO EXISTING PROGRAMS 6-4
6.3 REAL-TIME COASTAL FLOOD, MON1710RING NErWORK 6-5-
6.3.1 Type of Monitoring Network 6-5
6.3.2 Use of Data from Real-Time Monitoring Network. 6-6
6.4 FORECASTS AND WARNINGS FOR SIORM SURGE AND WAVES 6-6

APPENDICES

APPENDIX A: SPECIFICATIONS FOR ASERT SYSTEM
APPENDIX B: STORM SURGE AND WAVE MODELS
APPENDIX C: GLOSSARY OF ABBREVIATIONS
APPENDIX D: REFERENCES

vi i

LIST OF ILLUSTRATIONS

Figure 2.1 Relative Heights of Several Tidal Datums (Semidurnal Tide) 2-2
Figure 2.2 Tidal. Ranges Along the Connecticut Coast 2-5
Figure 2.3 Mean Sea Level Rise for Northern East Coast 2-6
Figure 2.4 Yearly Mean Sea Level Recorded at Long Term Tide
Gages in Long Island,Sound 2-6
Figure 2.5 Wave Characteristics 2-10
Figure 2.6 Existing Recording Tide Gages in Long Island Sound 2-14
Figure 2.7 Typical NOS Tide Station Instal 'lation 2-15
Figure 2.8 Typical Analog-to-Digital Recorder 2-16
Figure 2.9 Recording Tape Showing Time Divisions and Binary-Coded,
Digital Punch Out 2-16
Figure 2.10 Typical Bubbler Gage Installation 2-18
Figure 2.11 Typical Tide Record from Analog Recorder 2-18
Figure 2.12 Tracks of Seven Selected Hurricanes Crossing or
Approaching Long Island Sound 2-24
Figure 2.13 Tropical Storms and Hurricanes Passing Near
Long Island Sound 2-25
Figure 2.14 Expected Number of Tropical Storms and Hurricanes
per 100 Years Impacting the Long Island Sound Region 2-26
Figure 2.15 Selected Storm Surges at Stamford Harbor,
Stamford, Connecticut 2-29
Figure 2.16 FEMA Flood Insurance.Rate Maps for Section of
the Milford Coastline 2-32
Figure 3.1 Sample Storm Surge Forecast Guidance: Teletype Message
to Weather Service Forecast Offices 3-7
Figure 3.2 Forecast for Hurricane Gloria, Showing Probabilities
of Landf all 3-9
Figure 3.3 Connecticut Communities with NAWAS and COLLECT Systems 3-11
Figure 304 Connecticut Warning Flow Chart 3-12
Figure 4.1 Comparison of Forecast Vs. Observed Storm Surge at
Stamford, Connecticut 4-3
Figure 4.2 SLOSH Basins Along the Gulf of, Mexico and Atlantic.
Coastlines 4-6
Figure 4.3 Typical Pressure Transducer Type Tide Recorders 4-12
Figure 4.4 Acoustic Type Tide Gage 4-13
Figure 4.5 Typical Wave Measurement Gages 4-15
Figure 4.6 Sample Analysis of Wave Parameters 4-16
Figure 4.7 National Ocean Service NGWLMS System 4-22.
Figure 4.8 Sample Display of Tidal Data from New York Harbor
Tidal Gage System 4-26
Figure 4.9 Sample Display from Tidal Gage in San Francisco'Bay;
ALERT Type Network 4-28
Figure 5.1 Locations of Permanent Gage Stations for Tide and Storm
Surge Measurements 5-9
Figure 5.2 Typical Gage Station Installation 5-11
Figure 5.3 Radio Telemetry Network 5-12
Figure 5.4 Locations of Permanent Gage Stations for Tide, Storm
Surge, and Wave Measurements 5-15
Figure 5.5 Examples of Monthly Wave Data, West Coast Measurement
Network 5-22
Figure 5.6 Examples of Yearly Wave Data, West Coast Measurement
Network 5-23

LIST OF ILLUSTRATIONS (Cont'd)

Table 1.1 User Benefits from a Real-Time Coastal Monitoring
Network 1-9
Table 2.1 EPA Scenarios of Future Sea Level Rise 2-8
Table 2.2 National Ocean Service Subordinate Tide Gage Locations
in Long Island Sound 2-21
Table 2.3 Saffire/Simpson Hurricane Scale 2-23
Table 2.4 Structures Located in V-Zone 2-33
Table 5.1 Summary of Alternative Network Designs 5-7
Table 5.2 Sample Maintenance Schedule 5-32
Table 5.3 Estimated Maintenance Costs 5-32

ACKNOWLEDGMENTS

The authors wish to thank the many individuals in Federal, State and local
agencies and private organizations who provided information for this report.
Special thanks are extended to the members of the subcommittee on Coastal
Flood Warning-who supervised this project:

Ted Hart, Connecticut Department of Environmental Protection, Water Resources
Unit
Ralph Lewis, Connecticut Department of Environmental Protection, Natural
Resources Center
Todd Mendell, National Weather Service, Northeast River Forecast Center
Tom Oullette, Connecticut Department of Environmental Protection, Coastal
Area Management
Cynthia Rummel, Connecticut Department of Environmental Protection, Natural
Resources Center
Allan Williams, Connecticut Department of Environmental Protection, Natural
Resources Center

Principal authors of this report are Larry R. Johnston, L. R. Johnston
Associates, and David G. Aubrey, Ph.D., Woods Hole Oceanographic Institution.
Additional assistance was provided by Wayne Spencer of WHOI and Stanley Humphries,
consulting coastal geologist.

Funding for this project was provided by the Federal Emergency Management
Agency, State Assistance Program., under a Cooperative Agreement with the
Connecticut Department of Environmental Protection, The substance and findings
of this work are dedicated to the public. The author and. publisher are solely
responsible for the accuracy of all statements and interpretations. Such
statements and interpretations do not necessari ly reflect the views of the
Federal government.

Mention of commercial enterprises or brand names does not constitute endorsement
or imply preference by the authors, publisher, or Federal government.

1.0s INTRODUCTION AND SLIMMARY

Ll INTRODUCTIO

Automated flood warning systems were originally developed by the National
Weather Service (NWS) during the late 1970's in order to in.cre ase the amount
of warning time available to people who live and work in the floodplains of
rivers subject to flash floods. This NWS system, known as ALERT (Automated
Local Evaluation in Real-Time), relies on recent advances in microprocessor
and computer technology to provide accurate, real-time information on precipi-
tation amounts and stream level rises within a river basin.

The Connecticut Department of Environmental Protection (DEP) became convinced
of the, potential value of an ALERT system in Connecticut, and in 1982 it formed
an interagency Committee on Automated Flood Warning (CAFW). This committee
developed a Master Plan for a, statewide automated flood warning system known
as ASERT (Automated State 'Evaluation " in Real-time), to be devel Ioped jointly
with local,ALERT systems. The initial phases. of the ASERT system are currently
being installed, along with two pilot ALERT systems.

Within each river basin that is part of the Connecticut ASERT/ALERT system,
a series 'of automated precipitation gages @- and stream - gages collect ifif ormation
on rainfall amount and intensity and. amount and rate of rise in river levels.
This data is telemetered by VHF radio to NWS, State and local receiving stations
equipped with a microcomputer and software for analyzing, displaying and storing
the information. The system has. the capability to combine the rainfall and
streamflow data with a, hydrologic model of each basiN and to automatically
predict ex'pected 'flood levels and time .s.' Informat.i.on on predicted f.lood levels
can be compared to maps which delineate the areas that will be innundated
as flood waters reach different heights. Appropriate warnings may then be
issued for specific areas at risk.

Although the ASERT/ALERT system was designed for application in river
basins, DEP officials began to consider whether this same concept could be

1-2

applied to coastal flood warnings. Unable to identify a similar coastal system
in operation elsewhere, DEP submitted a proposal to the Federal Emergency
Management Agency (FEMA), and in 1985 received a grant to carry out a study
with two primary objectives:

(L) develop specifications for establishing an automated coastal flood monitoring
network which is compatible with the statewide ASERT system, and

(2) evaluate the feasibility of establishing a coastal flood warning system
utilizing information from the monitoring network.

L2, METHOW

In order to design the monitoring network and evaluate the feasibility
of a warning system, it was necessary to evaluate the following:

(1) Existing tide, storm surge and wave monitoring systems in use along the
Connecticut shore.

(2) Existing NWS forecast and warning procedures for storm surge and wave
heights.
(3) The current status of coastal flood warning procedures in Connecticut.

(4) Available technology that could be employed to collect flood data and
improve existing flood forecasts and warnings.

(5) Other potential . uses of information generated by a coastal monitoring
network.

Costs and benefits of impleme nting a State operated monitoring network
and warning system.

Investigation of the se 'and other issues resulted in findings which permitted
the formulation and evaluation of numerous alternative monitoring networks;
more detailed design of selected networks,, each with different capabilities
and degree of compatibility with the ASERT system; and recommendations for
providing coastal flood warnings. The major findings are highlighted in this
summary, and a full discussion is included in the main body of the report.

1-3

Ja FINDINGS

1.3.1 Existing Tide, Storm Surge and Wave Measurements

Staff, gages which can be read visually'.are located at many locations
along the Connecticut coast, primarily at ports,, marinas and Coast Guard stations.
These staff gages do not provide a. continuous or permanent record of actual
tide levels.

Recording tide gages are presently operated at five sites along the'Connec-
ticut coast. These gages. record the actual tide and storm surge levels on
either a continuous basis or at selected short intervals.

(1) 3:hames River estuacy at New London Owned and operated by the National
Ocean Service (NOS).

(2) Pgquonock River estuaty in Groton Owned and operated by the U.S. Geological
Survey (USGS), in cooperation with DEP.

(3) Mouth of the Connecticul River at Old Saybrook Owned and operated by
the USGS in cooperation with DEP.

(4) Bridgeport Harbor, Owned and operated by the NOS. The Bridgeport Weather
Service Office (WSO) also uses this gage.

(5) Stamford Harbor Owned by the U.S. Army Corps of Engineers (COE) and
operated by the USGS.

Presently, only the NWS recordings from the NOS gage in Bridgeport Harbor
are actually used as input to any storm surge forecasts and warnings.

There are no wave gages permanently operating.along the Connecticut coast.
Wave gages have been installed for short periods as part of research projects.

1.3.2 NWS Storm Surge and Wave Height Forecast and Warning Procedures

The NWS is. responsible fo r issuing all coastal storm forecasts and flood
warnings. In large part, these forecast s and warnings are based on meteorological
and oceanographic data generated by national and regional NWS -data collection
systems. Locally generated data of ten provide only a - minor , input to these
forecasts and warnings. The NWS uses four different procedures for preparing

1-4

storm surge and wave height forecasts and issuing warnings for the Connecticut
coast and Long Island Sound,, depending upon the type of weather condition.

(1) For hurricanes, surge forecasts and warnings are prepared by the National
Hurricane Center WHO in Miami. Hurricane forecasts and warnings are
not modified by local NWS offices, although Ahey may be supplemented
with local information that is more geographically specific. No separate
wave height forecast is prepared.

(2) For tropical storms, surge forecasts and warnings are prepared by the
NHC, but may be modified by the Weather Service Forecast Office (WSFO)
in New York City, if warranted by local conditions, as well as supplemented
with more detailed information. No separate wave height forecast is
prepared.

(3) For extratropical storms, s -torm surge forecasts are prepared by the NWS
National Meteorological Center (NMC) in Silver Springs, Maryland. The
New York WSFO reviews these surge forecasts and modifies them, as appro-
priate, based on local observations of actual wind, pressure and storm
surge conditions. The New York WSFO also prepares a separate wave height
forecast, and issues a coastal marine forecast and warning for Long Island
Sound (LIS).

(4) Wave height forecasts for non---,torm conditigns are also prepared by the
New York WSFO and routinely issued as part of the coastal marine forecast.

1,3.3 Connecticut Coastal Flogd Warniing Procedures

NWS forecasts and warnings for storm surge and wave conditions in LIS
are disseminated by a combination of NWS, Coast Guard, State agencies, local
officials, and news media. NWS warnings are provided directly to the Coast
Guard, Connecticut Office of Civil Preparedness (OCP), Connecticut State Police
(CSP), some municipalities, and major news media through official emergency
communications links of the National Warning System (NAWAS) and NOAA Teletype.
State officials in turn relay NWS warnings through the State warning network
directly to all municipalities and to selected news media.

NWS forecasts and warnings reach the general public through the NOAA
Weather Radio (NWR), Coast Guard marine radio (for mariners) and, most importantly,
through the 'news media, especially T.V. and radio. More specific warnings,
such as evacuation notices -for residents of vulnerable coastal areas, are
provided by local officials through such means as sirens, public address systems,
car-mounted loudspeakers, door-to-door notification, telephone calls, and

1-5

neighborhood associations. In some communities, local cable T.V. and radi o
stations may -issue specific information provided by the municipal civil pre-
paredness off ices.

1.3.4 Available and Emerging TechnolQ=_

NUMERICAL MODELS Complex numerical models for-predicting storm surge and
wave action have become feasible with the availability of massive data processing
capability of modern computers. An NWS model for predicting storm surge during
hurricanes and tropical storms, called SLOSH (Sea, Lake and Overland Surge
from Hurricanes), recently became operational for LIS. No equivalent models
for predicting storm surge during extratropical storms (northeasters), or
for predicting wave action, are presently operational for LIS.

INSTRUMENTATION. The recent availability of powerful microprocessors has
opened up new possibilities for real-time and near real-time data collection,
transmission and processing. The miniature size and low power requirements
of these microprocessors permit large amounts of data to be collected almost
insta ntaneously at remote locations, including subsea sites. Sophisticated
electronics have also enabled development of water level measurement sensors,
such as pressure transducers and acoustic devices, that do not have moving
parts and do not require contact with the water surface. Data may be processed
at field locations or transmitted via telephone lines, VHF and UHF radio,
and satellite for processing at central receiving stations.

Unfortunately, many of the recent technological. advances which permit
real-time collection and transmission of data are not based on in'dustry-wide,
uniform standards. Therefore, not all available systems and instrument components
are compatible with one, another. Efforts have just been initiated at the
federal level to establish instrument standards. with which future federal
procurements in this field must 'comply. The present lack of standardization
complicates the design of a coastal flood monitoring network for Connecticut,
and the study requirement to design 'a monitoring. network compatible with the
existing ASERT system somewhat limits the instrumentation that can be con-
sidered and the capabilities of an ASERT compatible system.

1-6

PROGRAM& Federal, state and local governments have developed programs which
utilize the new modeling and instrumentation technology for navigation, weather
forecasting, flood warnings, research and other purposes. The following federal
agency programs will have a direct impact on coastal flood data and warnings
in LIS and along the Connecticut shore:

(1) The NWS, FEMA, and COE jointly, in cooperation with coastal states, are
using the SLOSH model to estimate storm surge heights for any likely
track and intensity of a hurricane along the Atlantic and Gulf coasts.
Maps are prepared delineating coastal areas that will be flooded during
diff erent hurricanes.

(2) The NOS is planning to upgrade its entire network of permanent tide gages
to permit acquisition of real-time tide and storm surge data and to make
this data available to NWS and other users.

(3) While the new NOS system is being developed and installed, the NWS is
temporarily installing new telemetry equipment at selected NOS tide gage
sites which will permit near real-time transmission of tide and storm
surge elevations to NWS offices responsible for weather forecasts and
warnings.

The NOS upgrade of its tide gage network is still in a program development
and testing phase, and lack of a final choice by NOS for the total system
configuration and instrumentation to be used makes it unclear if a Connecticut
system will ultimately be entirely compatible with future NOS and NW technology.

Other programs developed by federal, state and local governments, often
in concert with private industry, provide valuable experience for evaluating
the feasibility of a Connecticut flood monitoring network and warning system.
The following programs which use real-time data are particularly relevant:

(1) New York Harbor Tidal Gage Syste This system of four automated water
level gages in New York Harbor is designed primarily as a navigation
aid, but is also used by the NWS to help prepare local forecasts for
LIS.

(2) Delaware Bay Navigation Projecl Similar to, but more ambitious than
the New York Harbor system, this project incorporates a numerical model
of tides and currents in Delaware Bay, and is capable of predicting tide
levels and currents up to 12 hours in advance.

1-7

(3) West Coast Wave Monitoring kletwork A-network of offshore wave buoys
and nearshore pressure gages along the west coast of the U.S. (and one
off the coast of North Carolina) provides data for evaluating *Iongshore
sediment transport and coastal erosion. Data is also used by, the NWS
to develop wave forecasts and provide real-time wave information in marine
weather bulletins. The system, is operated by the Scripps Institute of
Oceanography (SIO),, and it would be possible for Connecticut to link
up with this network for processing of LIS wave data.

1.3.5 Potential Uses of Data from Monitoring Network.

The primary intended uses of data from a.coastal monitoring network are:

(1) to improve both the extent and tim.01iness of the data base used to prepare
coastal storm forecasts and warnings, and

(2) to provide local communities with near -real-time information on actual
storm surge and wave heights compared to forecasts.

Otherpotential uses were also, identified, including:

aid to navigalion Real-time tide and wave data available during both
storm and norr-storm periods could benefit pleasure boaters and commercial
shipping interests', particularly harbor pilots. Accurate, tide data is
also useful for dredging projects and hydrographic surveys.

(2) research @ Storm surge and wave data are needed for research on coastal
processes within Long Island Sound, including circulation patterns needed
for understanding movement of pollutants.
(3) co@stal e ,ieerin Empirical data on storm surge and waves'are also
needed to improve the design and- construction of coastal structures,,
includi*ng protective structures such as groins, jetties, breakwaters,
and seawalls, and others such as marinas,, docks, and residential and
commercial buildings.

1-3.6 Costs 6nd'Benefitn

COSTS Development of a coastal flood monitoring network will be more costly
than a comparable ASERT/ALERT system operating within a river basin. Many
coastal network components are relatively more expensive because they must
be capable of. withstanding the harsh coastal environment. In addition, initial
installation costs will be greater than in a riverine Setting, and maintenance
must be performed more frequently and at greater costs. Depending upon the
final design selected, the coastal network may be able to utilize some existing

radio repeaters and base station components of the ASERT system and existing
recording tide gages, thereby holding down costs. Estimated initial costs
of a coastal monitoring network range from about $50,000 for a network that
measures only tides and storm surge and makes maximum use of existing instrumen-
tation, to over $400,000 for a network that also measures full wave characteristics
and employs all new instrumentation.

The State of Connecticut may be able to reduce significantly its costs
of installing and operating a coastal monitoring network by entering into
cooperative agreements' with other agencies such as NWS, NOS,, COE, and USGS
that have an interest. in the information to be produced by the network. It
may also be possible to spread the costs among more than one State agency.
Depending upon the final design. of the network,, the Bureau of Waterways of
the Department of Transportation (DOT) and the University of Connecticut (UCONN)
may derive significant benefits from the data, and could be approached for
sharing the costs of initial network installation and/or operation and main-
tenance. It may also be feasible to charge user fees for access to data by
private groups such as harbor pilots, dredging operations, researchers, design
engineers, etc.

The costs of developing a suitable extratropical storm surge model for
LIS will be substantial. Modification of an existing model and model verification
can be accomplished for a cost of between $50,000 and $100,000. Development
of a large set of scenarios to, predetermine areas to be innundated from a
particular storm may cost an additional $150,000 or more. Development of
a suitable numerical wave model may cost about $30,000.

BENEEITS, Because of the large number of potential users (Table 1.1), benefits
from a monitoring network andnear real-time dissemination of data will be
substantia4 though difficult to quantify.

(1) Co astal flood warnings can be enhanced, permitting reductions in property
losses and unnecessary, evacuations:

(a) The availability of More precise and timely data from several locations
along the coast should enable the NWS to improve the accuracy and
timeliness of forecasts and warnings

1-9

13IRNRPITS

coastal residents and Surge and wave height data for design
property owners purposes.
Municipal agencies Actual conditions for storm surge
and wave heights

Office of Civil Preparedness Actual conditions for storm surge
and wave heights

DEP, Natural Resources Center Data for Inclusion in its natural
resources invEintory

DEP, Water. Resources Unit Hydrologic studies of the coastal
reaches of river basins; revisions
to Flood Insurance Studies

DEP, Water Compliance Vnilt Water quality studies of LIS, includinr-
currents, movement of pollutants,
circulation patterns, etc.

DEP, Coastal. Area Management Longshore sand transport, - coastal.
erosion, evaluation of. coastal structures

University of Connecticut and Short- and long-term research -studies
educational institutions on coastal processes, circulation,
currents, etc.

National Weather Service Storm surge forecasts and present
levels; wave height forecasts and
current conditions;. verification
of forecast models.

Federal Emergency Management Agency Revisions to Flood Insurance S tudies;'
Hurricane Preparedness Studies

Corps of Engineers Hurricane Preparedness Studies;
dredgi,ng of federally maintained
channels; port and harbor studies;
other coastal studies

National Ocean Service Short- and long-term sea level variation

Coast Guard Sea surface and weather conditions,
tide levels

Harbor pilots and marine Industries' Accurate tide'' levels for movement
of vessels in and out of harbors

Pleasure boaters and marina owners- Timel information on wave conditions

Storm surge and wave energy and
Coastal engineers spectral .'data for design of coastal
structures

TABLE 1.1: User Benef its from a Real-Time Coastal Monitoring, Network

1-10

(b) The availability of accurate, real-time data for specific coastal
locations should enable community officials to supplement regional
NWS forecasts and warnings with more precise local warnings.

(c) The benefits of improved warnings can be increased still further
if the information on storm surge and wave heights is combined with
appropriate inundation maps.

(2) Navigation improvements:

(a) Commercial shippers can save money by loading vessels to capacity,
reducing waiting time for harbor entry or exit, and avoiding groundings.

(b) Commercial fishermen can locate best fishing areas and avoid groundings.

(c) Pleasure boater and marina operators can make more informed decisions
about safe boating conditions and channel depths.

(3) Research data:

(a) Surge and wave data for improved engineering design of coastal struc-
tures.

(b) Improved understanding of sand movement and beach erosion.

(C) Tide, surge and wave data for improved understanding of water, quality,
including movement of oil spills and other pollutants.

JA CONCLUSIONS AND RECOMMENDATIONS

1.4-1 Conelugions

The present system of issuing fi2recasts and warnings for coastal storms
and f lo oding is less than oDtimal Although existing warning procedures appear
adequate to avoid loss of life and serious injury, improved warnings which
provide more precise information on the timing, location, and extent of flooding
would allow further reductions in property losses and avoid some unnecessary
evacuations. There is room for improvement in most aspects of the total system
and at every level of government, including:
(a) quantity and quality of data used in preparing forecasts
(b) timeliness of data 'availability

(d) use of new and improved models for forecasting storm surge a nd wave
heights

(e) methods of disseminating forecasts and warnings to local communr
ities

(f) development of innundation maps that can be used with flood warnings

W metbods of 'providing warnings and instructions to residents of coastal
f loodplains

Although ents in 'each of these e certainly possible.,
not all are eQual.ly teasible at the present time, Nor will golential improvements
in each area yield egual results in reduciiiii, flood losses
(a) Only limited improvements appear feasible to the existing NWS forecast
and warning system for hurricanes and tropical storms. Because
hurricane warnings are already conservative (i.e. attempt to warn
of the most severe likely impact), the limited improvements will
probably have little effect on reducing flood losses, especially
in Connecticut where the coastal flood zone is relatively small.

(b) More significant improvements in storm forecasts and flood warnings
appear possible for extratropical storms (northeastets).

(c) The most significant improvements should result from supplementing
NWS regional forecasts with more precise information for particular
geographic areas.

The primary responsibili4 fgr providing stol:m, storm surge, and
forecasts and 'warnings should remain with the XWS. Historically, issuance
of coastal storm forecasts 'and Warnings have been the exclusive province of
the NWS. Technological advances have now made It possible for other levels
of government and private concerns to prepare forecasts and issue 'warnings,
although they must still rely upon the NWS for much of the essential data.
This ability makes it attractive to seek ways of supplementing or replacing
NWS procedures that do not take advantage of the latest technology or do not
provide the desired site specific information.. Nevertheless, there are compelling
reasons to continue reliance upon the NWS as the primary provider of forecasts
and warnings.

(a) The NWS has a long'. history. of providing reasonably accu rate forecasts
and credible warnings.

1-12

(b) Current and planned improvements in the programs of NWS and other
federal agencies will make possible improvements in NWS forecast
capabilities.

(d) Even if the State did develop its own forecasting system, the NWS
would still issue its own forecasts and warnings.

(e) There is need for consistency of information during emergencies.
Conflicting information coming from different sources during emergencies
has long been recognized as a major cause of improper response or
lack of response by those located in areas at risk.
1he State Can initiate several actions w'hich wi-11 result i
foreelLsts and warning,% State activities should
(a) enhance the capabilities of fe 'deral agencies to perform data collec-
tion, forecast and warning responsibilities; and

(b) supplement the federal agencies' regional forecasts and warnings
with more detailed information in specific geographic areas regarding
the extent and timing of anticipated flooding.

To avoid unnecessary expenditures, public confusion over differing messages,
and conflicts with federal agencies, the State should not:
(a) duplicate federal programs and responsibilities, or
(b) issue information that confliCts with NWS warnings.

Q1 12evelopment of a coastal flood monitorinLy network for real-time measurement
of tide and storm surge levela and which would be compatible with the existing
ASRRT system is feasible and would provide recognizable benefits, both Quantif iahlc
and ngn-Quantifiable.,
(a) Improved. flood forecasts and warnings.
(b) Improved navigation.
(c) Improved data for design of coastal structures.

Collection of wave dat a, while providing im@Qrtant information for flood
and othgr Id not be completely compatible with the ASERT
aystem.
(a) Collection of wave data can be made compatible with ASERT, but requires
some compromises on the quality of wave data and/or the ASERT system.

(b) A separate wave data network could be established to supplement
the ASERT compatible tide/storm surge network.

1-13

1.4.2. Recommendations

(1) The Stfite -.q,hould proceed with develoDing a coastal flood monitoring network
Important aspects of this network include:
(a) Utilize the exist .1 ing network of tide ga'
ges in LIS, including planned
improvements, to the extent possible.

(b) Add new tide, storm surge, and wave measurement stations where needed.

(d) Make decisions on which optional network (described in 1.5 below)
should be implemented, ba.sed on budgetary and other considerations.

(2) The State should tr local officials in the proper use of the monitoring
network,

(a) Use and maintenance of local receiving (base) stations.

(b) Intrepretation of tide, storm surge, and wave data from the monitoring
network and how to use the data to supplement NWS forecasts and
warnings.

(3) At the present time, the State shotild not devel6p' its own storm 'surL7 a
or wave models for Lang Island Sound Instead, it should:

(a) Work with the NHC, FEMA, and the'COE to ensure that the SLOSH model
for LIS is used most effectively.

(b) Encourage the NWS to develop a numerical storm surge model for extra-
tropical storms for LIS.

1-14

1,5 RECOMMENDED MONITORING NETWORKS

1.5.1- Number and Locatign of Gagres

Empirical data suggest that storm surge along the coast can be adequately
monitored with five stations:
(1) Stonington - New London reach: area of historical uncertainty.
(2) Waterford - East Haven reach: constant slope in storm surge.
(3) New Haven area: local maximum in storm surge.
(4) Milford - Bridgeport reach: low point in storm surge.
(5) Stamford - Greenwich reach: area of highest surge.

.Wave hindcasting techniques suggest that at least three wave stations
should be established:
(1) Madison - Old Lyme reach: subject to both easterly swells and local
winds.

(2) New Haven area: mid-coast; subject to long fetch winds from both east
and west.

(3) Stamford - Greenwich area: mostly local winds; complex shoreline and
offshore bathmetry; subject to long easterly fetch.

1.5.2. Optional Monitoring Nptwork Degigll&

In addition to the number and location of gage stations,, the optional
designs for a monitoring network reflect consideration of: type of water
level and wave sensors; compatibility with ASERT,- utilization of existing
equipment, programs and procedures; uses of data in addition to. stor m warnings;
costs of establishing and maintaining the system.

ASF,RT COMPATIBLE NETWORK

Three principle options for an ASERT compatible network are available.

(A) Tide and Storm Surge Measurements On4: Use existing recording tide
gage stations at:

1-15

(1) Stamford Harbor
(2) Bridgeport Harbor
(3) Mouth of Connecticut River (Old Saybrook)
(4),Thames River (New London)

Add a new station at:
(5) New Haven.Harbor.
In addition, two "roving" gages should be temporarily (approximately
one year) installed at various locations along the coast to provide g ood corre-
lation with the permanent stations. These roving gages could be placed in
harbors and other easily accessible locations.

(B) Tide, S torm Surge and Wave Measurements Use existing recording tide
gage stations at:
(1) Bridgeport Harbor
(2) Mouth of Connecticut River (Old Saybrook)
(3) Thames River (New London)

New stations should be added at:

(4) Stamford Harbor Breakwater
(5) New Haven Harbor Breakwater
As with the previous option, two roving gages should also. be installed
at various locations along the. coast. However, . the roving gages should be
installed at Jocations along the open coast to permit. measurement of wave
characteristics. Because installation in open water locations.is more expensive
and wave characteristics are highly variable, these gages . should remain in
each location at least two years or until a good set of wave 'data are obt .ained.

Because ASERT/ALERT accepts data on a random or eve nt reporting basis,
in order. to collect wave data and still have the network. be. compatible with
the ASERT system lity must be compromised:
wave data or system reliabi
(1) only average wave height and wave length are obtained instead of the
usual significant wave heightq significant wave period, and wave spectral
data.

(2) Significant wave height, significant -wave period, and wave spectral data
can be obtained, but only processed data can be sent to ASERT base stations,
and the raw wave data (useful for research. and verification purposes)
may be losti

(3) Multiple transmissions of wave data are sent to the base station, increasing
the chance of that data getting through, but crowding the airways.

1-16

(C) Separate Storm Surge and Wave Networks To collect uneompromised wave
data and still utilize the ASERT microcomputer and software (some ASERT software
modifications will be needed for any of the alternatives considered), a separate
data transmission system is needed for wave data. Two options exist: a one-
way communications network (like ASERT), and a two-way communications network
that would permit changing sampling frequency of wave sensors from the base
station. If the ASERT transmission system is not used, wave directional data
could also be included providing a proper wave gage is installed. Another
option would be to link the wave data transmission system to the Scripps Institute
of Oceanography (SIO) co mputer via telephone lines for processing of wave
data by SIO.

DATA COLLECTION NFrWQRK INDEPENDENT OF ASFRT If the State decides that ASERT
compatibility is less important than collecting the full range of wave data,
a totally independent monitoring network with two-way communications could
be established that also utilizes a separate computer and specialized software
for processing wave data.

COSIS Costs for the least expensive alternative (ASERT compatible, no wave
data) would be approximately $50,000 and range upward to more than $400,000
for the independent network.

DATA AVAILARTLITV All data will be transmitted by VHF radio to existing base
stations at the Northeast River Forecast Center (NERFC) in Bloomfield and
the State DEP offices in Hartford. In addition, it is ree ommended that new
base stations be established at the Bridgeport WSO and Hartford WSO, and at
the two State warning points (OCP and CSP) in Hartford. Each local community
that desires to participate in the system would need to purchase its own base
station. Arrangements should be made so that data can also be accessed by
modem and telephone lines by users who do not need a base station.

2-1

2.0e TIDIE AND TIDAL FLOODING IN LONG ISLAND SOUND

In order to design a coasta I flood monitoring network which will accurately
measure storm surge and wave action along the Connecticut shore, it is necessary
to understand bow normal, tidal fluctuations. and storm induced flooding occur
in Long Island Sound. "This section r,eviews available information on tides,
storm surge and waves in Long Island Sound and along the Connecticut coast.

TIDAL DATUMP

Storm surge, heights of structures, soundings, and other coastal measurements
must have numerical values above or below some reference base. The logical
choice for the base is the ocean surface. But, since the ocean (and land)
surface moves up and down,At must be 11 ixed" in order to become a suitable
reference base. The result of mathematically fixing the ocean.surface in
terms of an observed tidal phenomenon is called a tidal datum. (1)

Many. tidal datums are in' use and are often confused'by coastal residents
and others. The 'official tidal datums for the U.S. are established by the
NOS (2). The tidal datums and related terms most relevant to a flood monitoring
network are defined below and illustrated in Figure 2.1.

National Tidal Datum Epoch - The specific 19-year period adopted by the NOS
as the official time segment over which tide observations are taken and reduced
to obtain mean values for tidal datums. It is necessary for standardization
because. of periodic and nonperiodic trends in sea level. The present National
Tidal Datum Epoch is 1960 through 1978.

Mean *Low Water (MLW) -- The. average. of all the low water heights observed
over the National Tidal Datum Epochl.

Mean Lower Low Water (MLLW) -- The average of the lower low water height of
each tidal day observed over the National Tidal Datum Epoch. Mean Lower Low

IFor stations with shorter series, simultaneous observational comparisons
are made with a control tide station in order to derive the equivalent datum
of the National Tidal Datum Epoch. (2)

2-2

MHW
MSL Aihhhh
WGVD TVVYVYYV
MLW
HLLW
1 5 9 13 17 21 25 29 DAYS

MHW Mean High Water
KSL Mean Sea Level
NGVD National Geodetic Vertical Datum (1929)
MLW Mean Low Water
14LLW Mean Lower Low Water

FIGURE.2.1: Relative Heights of Several Common Tidal Datums
(Semidiurnal Tide)

2-3

Water is the tidal datum for soundings and depth c ontours on nautical charts2.
Mean High Water (MHW) -- The aver e of all the@high water heights observed
over the National Tidal Datum Epoc;y. Mean High Water is the reference base
for structure heights, bridge clearances, etc. The shoreline on USGS quadrangle
maps is approximately MHW.

National Geodetic Vertical Datum (NGVD) of 1929 A fixed reference adopted
as a standard geodetic datum for elevations determined by leveling. The datum
Was derived for survey from a general adjustment of the first-order leveling
nets of both the United States *and Canada. In the adjustment, mean sea level
was held fixed as observed at 21 tide stations in the United States and 5
in Canada. NGVD (formerly referred to-as Mean Sea Level, and shown as such
on older USGS quadrangle maps) is the standard datum of elevations throughout
the U.S. Because there are many variables affecting sea 'level, and because
the geodetic datum represents a best fit over a broad area, the relationship
between the geodetic datum and local mean sea level is not consistent from
one location to another in either time or space. For this reason, NGVD should
not be confused with mean sea level.

All other elevations are referenced to NGVD, which has an elevation of
0.0. For example, a value- for MHW of 3.0 feet means that MHW is 3.0 feet
above NGVD. An increase in relative sea level such that MHW increases 0.4
feet from one National Tidal Datum Epoch to another would mean that MHW had
risen 0.4 feet with respect to NGVD, and the adjusted value of MHW would be
3.4 feet. The elevation of flood levels on coastal flood maps are given as
elevation above NGVD.

Mean Sea Level (MSQ - The arithmetic mean of hourly heights observed over
the National Tidal Datum Epoch. Shorter series are specified in the name;
e.g., monthly mean sea level and yearly mean sea level.

TIDAL VARIATION I N LONG ISLAND SOUND

Tides in Long Island Sound are semidiurnal with two high tides and two
low tides occurring each tidal (lunar) -day (5). A tidal day is the time. of
rotation of the earth with respect to the moon, and its mean value is approximately

2NOS recently changed,tbe tidal datum for the Atlantic coast from m ean low
water to mean lower low water, which 'is the datum in use on the Pacific and
Gulf coasts. Although new nautical charts will have the chart datum lowered
from mean low water to mean lower low water, actual sounding figures, isobath
and other information will not be changed due to: a), offsetting effects of
rising sea level with change from 1941-1@59 datum to 1960-1978 datum; b) thickness
of lines on nautical charts and bathymetric maps;- and c) roundoff procedures
and accuracies in, datum determinations, hydrographic,- surveying, and nautical
charting. (3)

2-4

equal to 24.84 hours. (2) Hence, each high tide follows the previous high
tide by approximately 12 hours and 25 minutes.

Because of the Sound's size and shape, it amplifies the oceanic tide,
and the tidal range in the western Sound is larger than the tidal range in
the east. At Greenwich, for example, the average tidal range is about 7.2
feet while at Stonington the range is only about 2.5 feet (6). High and low
tides also occur at different times throughout the Sound. High tide at Greenwich
occurs approximently two hours later than high tide at Stonington (7). Figure
2.2 shows the variation in normal tide ranges at selected points along the
Connecticut coast.

Just as' Long Island Sound affects the timing and amplitude of oceanic
tides, the bays and estuaries along the Connecticut coast also modify the
timing and amplitude of local tides within the Sound. Along most of the coast
these local effects are minor, but become significant in ihe upper tidal reaches
of the Connecticut and Thames rivers. (7)

Ll RlPY.ATTVF SFA TYVEL RISE

Relative sea level has been rising over the past 15,000 years as the
earth's climate has warmed, and as the earth has undergone tectonic activity.,
From tide measurements, the NOS has developed trends in the relative rise
of yearly mean sea level for the period 1940 through 1980. The average for
the entire . U.S. coast is 1.3 mm/year. , For the northern east coast the rate
is considerably higher at 2.6 mm/year (see Figure 2.3). Figure 2.4 shows
the increase in yearly mean sea level for the two long-term gages on the north
shore of Long Island Sound. (1), These stations and other data for northern
Long Island Sound show relative sea level to have increased about 20-25 cm.
over the past 100 years (a rate of 2.0-2.5'mm/year). (8)

Recent research (102,103) has found that relative sea-leVel rise along
the U.S. northeast coast is due not only to global- increases in sea level,
(due to thermal expansion of the 'ocean surface and melting of glaciers in
response to heating of the earth's surface), but also to a large effect from

*.........

ae 1%

.00,
SOURCES: U.S. Army Corps of Engineers. 1980. Tidal Flood Profiles, Ne
England. Hydraulics and Water Quality Section, New England Divis
and
National Ocean Service. 1984. Tide Tables: 1985 High and Low
Water Predictions, East Coast of North and South america, Incl
Greenland. NOAA, U.S. Dept. of Commerce.

MEAN

kMNAL GEODETIC VERTICAL QATUM Or 1929

MEAj Low wATER

FIGURE 2.2: Tidal Ranges Along the Connecticut Coast

2-6

7.0-

6.8-

6.5-

L2-

;940 tim 3im lira 3M
YM

SOURCE: Hicks, Steacy D. 1983. Sea Level Variations
for the United States, 1855-1980. National Ocean
Service, NOAA, U.S. Dept. of Commerce.

FIGURE 2.3: Mean Sea Level Rise for Northern East Coast

YERRLY MEAN SEA LEVEL YEARLY MEAN SEA LEVEL
STATION NO. 8516990 STATION NO. 8461490
WILLETS POINT, NY NEW LONDON, CT

7.7
ISIS* Sin tim tin Ito = I" t= two no SIM I= silo Uin Sim Him 11;w loin Hiv I&
YEM Tw

YEARLY MEAN SEA LEVEL &JI. YEARLY MEAN SEA LEVEL
STATION NO. 8518750 STATION NO. 8467150
NEW YORK (THE BATTERY], NY BRIDGEPORT, CT

11A.

LI LIS

4,3 4J
fm lifis Him Uis tin tin 4w aim' 'Sim' 'aim d@11' UiS ING Ii2lt 40 1%- -IIiF0 dill
YERR
- V-- V@

w tm@

SOURCE: Hicks, SteaCy D. 1983. Sea Level Variations for the United States,
1855-1980. National Ocean Service, NOAA, U.S. Dept. of Commerce.

.FIGURE 2.4: YearlyMean Sea Level Recorded at Long Term Tide
Gages in Long Island Sound

2-7

-isostatic adjustment. As the North American glaciers melted over the past
10-15 thousand years, land previously covered by glaciers has adjusted to
removal of the weight of the glacial mass. Land which was formerly depressed
below the glaciers is now rebounding; so relative sea level has been falling.
Along the edges of the glacial mass, which includes the Long Island Sound
region, land was elevated somewhat, and has been falling, so relative sea
level has been rising. Thus, Connecticut relative sea levels are a combination
of global processes and localized response to retreat of.the glacial mass.

This relative. rise in sea level is expected to continue over the next
century, and, the rate of increase is anticipated to increase, but the future
rate of relative sea level rise is uncertain. Recent reports by the Environmental
Protection Agency (EPA) in 1984 (9) and the National Academy of Sciences (NAS)
in 1983 (10) examined the effect of atmospheric concentrations of carbon dioxide
and trace gases (methane, chlorofluorocarbons, etc.) on relative sea level
rise. Increased concentrat ions of these gases may act to trap the long-wave
radiation re-radiated from the earth's surface, resulting in heating of the
atmosphere commonly known as the. greenhouse' ef f ect. This heating of the
atmosphere in turn would warm the ocean's surface, c ausing it to expand and
produce a relative sea-rlevel rise, and perhaps melt the glaciers (this effect
is much more uncertain),

Although W cannot -be asserted with any confidence what 'the effects on
sea level will be, there are several estimates of these effects. The NAS antic-
ipates a rise in sea-level of 70,cm (2.3 feet) would occur over the next century,
given plausible models of atmospheric warming. EPA, provides several estimates
of global sea level rise to the year 2100 (Table 2.1).n Under EPA's high scenario,
sea level would rise 345 cm (11.3 feet) by 2100. Under their conservative
scenario, sea level would rise 56 cm (1.9 feet) by 2100. EPA f eels that a
global sea level rise between 144 cm (4.8 feet) and 217 em (7 f eet) by the
year 2100 is most likely. By the year 2000, EPA's more likely estimates are
that sea level will rise between 8.8 em (0.29 ft) and 13.2 cm (0.43 ft).
EPA also estimates that along most of the Atlantic and Gulf coasts of the
U.S, the rise will be 18 to 24 em (0.6 to 0.8 feet) more than the global average.
The greatest changes will not occur until after, the. turn of the century.
All projections are significantly higher than current trends in sea level

2-9

SCENARIOS OF FUTURE SEA LEVEL-RISE
(centimeters)

Year

2000 2025 2050 2075, 2100
Scenario

High 17.1 54.9 116.7. 211.5 345.0

Mid-range high 13.2 39.3. 78.9 136.8 216.6

Mid-range low 8'.8 26.2 52.6 91.2
Low 4.8 13.0 23.8 38.0 56.2'

Current Trends 2.0-3.0 4.5-6.8 7.0-10.5 9.5-14.3 12.0-18.0

SOURCE: Hoffman, John S., et. al. 1983. Projecting Future Sea
Level Rise: Methodology, Estimates to the Year 2100,
and Research Needs. U.S. Environmental Protection Agency.

TABLE 2.1: EPA Scenarios of Future Sea Level Rise

2-9

rise.

M TM SURGE, AND WAVE MEASUREMENT'S IN LONG ISLAND SOUND

Waves

WAVE CHARACTERISTICS Waves, created - by wind blowing over the surf ace of
the water, are the major factor in determining the geometry and composition
of beaches, and cause most.of the damage in coastal areas, including coastal
erosion and damage to structures. Waves.are usually defined by their height,
length, and period (Figure 2.5), which are determined by the fetch (the distance
the wind blows over the sea in generating'the waves), the wind speed, the
length of ' time.. the wind blows, and the decay distance (the distance the wave
travels after leaving the generating area). Generally, the longer the fetch,
the stronger the wind; and the longer the wind blows, the larger the waves.

Wave" action is extremely complex. The wind simultaneously generates
waves of many heights, lengths, and periods as it blows over the water. -In
areas of shallow water, the water depth also affects the size of waves. Waves
are subject to refraction (bending), depending on the wavelength in relation
to water depth; diffraction (energy transfer along the crest of the wave);
and reflection (as they encounter natural and 'manmade barriers. As a wave
moves toward shore, it reaches a depth of water so shallow that the wave collapses
or breaks. This depth is equal to about 1.3 times the wave height.

Because of bottom friction and wave scattering, there is considerable
alongshore variability in wave behavior. This variability is obvious to anyone
who ha s observed waves breaking on the shore. The variability exists in both
space and time. The time-variability reflects the development of the storm,
including the wind speed, wind direction, and location of the storm center
or front. The spatial variability reflects the dissipation and scattering
of waves as they travel towards shore. As an example, the sheltered areas
behind Fishers Island will experience distinctly different waves than the
shoreline not in the lee of the island.

2-10

Direction of Wove Travel

Lz Wove length
Wove Crest ,,H =Wove Height
@--Crest Length Wove Trough
Region Trough Length---@ I @'.lwoter Level
Region d z Depth

Ocean Bottom

SOURCE: U.S. Army Coastal Engineering Research Center. 1977. Shore Protection
Manual, Volume I. Corps of Engineers, Dept. of the Army.

FIGURE 2.5: Wave Characteristics
ength
W
0n
Trou gh Length---7

2-11

For modeling and engineering design purposes, the "significant wave height"
and "significant wave period" are often used, and may be considered to represent
the average height and period of the dominant'waves. More complex measurements
of the "energy spectral' and "directional spectra" of waves take into account
the many different types and directions of waves that occur at any particular
t im e. Because of their h.ighly technical -nature, no further description, of
these. quantative measures of wave characteristics is provided in this report. (11)

WAVE MEASUREMEN TS There are no long-term measurements of wave character-
istics for Long Island Sound. , No wave buoys.or other instruments for measuring
wave characteristics have been 'permanently installed in the Sound. In its
1976 study,,(12) of the effects of coastal, storms on the Connecticut coastline,
the Corps of Engineers (COE) found that no wave measurements or statistical
wave data were available for the area. Limited wave measurements for specific
locations and for short durations have been obtained as part of coastal research
studies performed at the Universi ty of Connecticut (13) and the State University
of New York at. Stony Brook (14). As input, to its LIS,Marine. Weather Bulletin, the
NWS may receive reports from Coast Guard stati ons and ships concerning observed
wave heights (15).

The COE (12) has estimated, that the maximum height of waves breaking
at exposed locations along the Connecticut- shor eline with tides three feet
or more above mean high water ranges from about three to eight feet, with
the possibility of larger waves during very high tides. As part of the recent
update of Flood Insurance Studies, FEMA contractors found that for a. storm
surge with a. @return frequency of 100 years, wave heights would range from
5.5 to 6.5 feet above the stillwater level, at exposed locations. The maximum
wave crest' was determined to be 18. feet above NGVD at Greenwich.. Predicted
wave heights were about one foot higher in the western portions of the Sound,
than in the east. (16)

Tides and Storm Su.

STORM SURGE. Storm surge is defined as the difference between the observed
water level and that which would have been expected at the same place in the
absence of the storm. Surge height during a particular storm depends primarily

2-12

on the following processes, although other factors also exert some influence: (6)

(1) Atmospher' differences. The sea level surface is elevated
in response to the low pressures associated with storms. In the open ocean,
a pressure drop of 33.86 millibars (one inch) will lead theoretically to a
13 inch rise in sea surface elevation (7).

(2) Wind set=UD. Wind stress on the water surface will cause water
levels to increase along the fetch in a downwind direction. Wind stress,
and hence, wind setup are proportional to the square of the wind velocity-
Wind set-up is also enhanced by decreasing depth. (18)

(3) Wave set-Up, Breaking waves create turbulance and actually move
water nearer shore, resulting in increased height of the water level surface
in this area. Wave set-up may account for as much as 3.3 to 6.4 feet of storm
surge height at a beach. (19)
(4) Rainfall Intense rainfall can lead to an increase of water 'levels,
especially in estuaries.

(5) Storm motion effects The intensity of the storm, the speed of
storm movement, and the angle of the storm track at the shoreline can affect
storm surge (11,17).

(6) Shoreline configuration and basin bathymelly. In general, configurations
which favor an increase in the, range of astronomical tide will also favor
an increase of storm surge heights (11).

.TIDE AND STORM SURGE MEASUREMENTS. As described below, considerably more
data is available on tide and storm surge levels for LIS than for wave characer-
istics.

Staff Gages, Coast Guard stations and many marinas and port terminals
have installed tidal staff gages that can be read visually. The COE has installed
a tide staff gage in the ports of New London, New Haven, and Bridgeport, and
in Stamford Harbor at the Hurricane Barrier. Most of these gages are located
on a pier or dock in a protected portion of the harbor. Readings are not
usually taken at regular intervals, and records of readings are not generally
maintained. Often, temporary tide staff gages are installed for special projects,
such as dredging. (20,21,22,23,24,25)

2-13

Recording Gages Recording tide gages are presently in operation at
five locations along the, Connecticut Coast (Figure 2.6):

(1) Thames River estuary at New London Owned and operated by the National
Ocean Service (NOS).-

(2) P uonock River estuary in Groton. Owned and operated by the U.S. Geological
Survey (USGS) in cooperation with DEP.

(3) Mouth of tb e Conaecticut River at Old Saybrook'. Owned and operated by
the USGS in cooperation with DEP.

(4) Bridgeport Harbor, Owned and operated by the NOS. The Bridgeport Weather
Service Off ice (WSO) also uses this gage.

(5) Stamford Harbor Owned by the U.S. Army Corps of Engineers (COE) and
operated by the USGS.

National Ocean Service. The NOS owns and operates the tide gages at
New London and Bridgeport (NOS has an additional recording gage in Long Island
Sound at Willets Point on the north shore of Long Island (7)). These stations
are part of the NOS network of stations,known as NWLON (National Water Level
Observation Network), which includes 225 permanent gage stations. The New
London station is located at State Pier No. 1 in the Thames River (Figure
2.6 (1)). It has been in operation since 1938. The Bridgeport gage is located
at Hitchcock Marina in Bridgeport Harbor (Figure 2.6 (4)). It was originally
installed in 1932, but data is not available for the entire period. (7,26,27,28,29)

Figure 2.7 illustrates a typical. NOS station installation. Each station
inc ludes a primary recording gage. and a reference staff gage. The ref erence
staff is connected by precise leveling to. nearby bench marks. Generally,
the station also includes a backup recording' gage.

The' primary gage is an elect ro-m echanic al Analog-to-Digital Reco .rder
(ADR) (typically a Fisher Porter or Leupold & Stevens type) which measures
water level by means of a float and wire attached to a spring-loaded drive
(Figure 2.8). As the water rises and falls, the drum rotates and turns a
shaf t. A mechanical pin assembly, driven by a timer, converts the analog
signal to a digital reading by punching the elevation into a time sequenced
paper tape (Figure 2.9). Water levels are recorded every six minutes. To

N
------- ....

<
A-,
\px"A.--N@

5,,, lid

IIc Thaman RivAr pnt-Ijary at Now London. owned and op
the National Ocean Service (NOS).
5 (2) Poquonock River Pa1*11ary in Grotgn. Owned and operat
U.S. Geological Survey (USGS) in cooperation with.DEP.

(3) Mouth of the Connecticut River at Old Saybrook.
operated by the USGS in cooperation with DEP.

(4) ArtAgpport HaLbnz. Owned and operated by the NOS. The
Weather Service Office (WSO) also uses this gage.

(5) 5 t a m f e5 zA-1L&Lb=. Owned by the U.S. Army Corps of
(COS) and operated by the USGS.

FIGURE 2.6: Existing Recording Tide Gages in Long Island Sound

2- 15

AN Gage
(6 min. sampling Interval)

Observer
(gage-stsff observations daily) Survey Rod

Instrument
Shelter

Pier Leveling Instrument
(station typically
leveled semiannually)
Water Line Bench
Mark

Tide Staff

Orifice

Float

Stilling Well

SOURCE: Deibel, Lawrence E., and Barbara A.' Zumwalt. 1085. Next Generation
Water Level MeaBurement SyStem Program. By the mitre Corporation
for National Ocean Service, NOAA, Dept. of Commerce.

@.FIGURE 2.7: Typical NOS Tide Station Installation

2-16

FIGURE-2.8: Typical Analog-to-Digital Recorder

04, 93 -ater level
04.97
03 -01
.1.07

sprocket drive holes

clock time

-translator o1iinmerif holes

daily serial number

SOURCE: Coast and Geodetic Survey. 1977. manual
of Tide Observations. Publication 30-1,
U.S. Dept. of Commerce.

FIGURE 2.9: Recording Tape Showing Time Divisions
and Binary-Coded Digital Punch Out

2-l' 7

reduce wave eff ects on the reading, the float and wire are mounted in a vertical
pipe with a small orifice at the bottom, referred to as a stilling well.
Water level heights are recorded with a resolution of 0.001 foot, and an accuracy
of about 0.01 foot.

An analog recording pressure gage (bubbler gage) is often used to provide
backup data (Figure 2.10). , These gages rely on changes in water pressure
to indirectly measure the rise and fall of water level. Nitrogen is bubbled
through an underwater tube, and the pressure, encountered activates a bellows
which in turn moves a pen across a sheet of recording paper mounted on a rotating
drum (Figure 2.11). Accuracy ranges from 0.1 foot in low range. areas
to +/- 0.5 foot in high range areas.

Five times' per week, local NOS tide observers check the tide stations
and compare the gage readings with visual water readings on the reference
staff. The observer enters the staff reading into a special log form, and
also marks the correct time directly on the . recording charts. The punched
paper tapes, analog recordings, and comparative staff readings are mailed
to NOS headquarters at the end of each month by the tide observer. Data are
analyzed and recorded by NOS and permanently retained. , Anyone may request
(purchase) tidal :records for these stations from NOS. Data are generally
not available until at least three months after. it has been transmitted to
NOS headquarters. NOS annually publishes a set of tide tables (7) for these
and other NOS stations that provide predicted high and low tides.for the entire
year. NOS also prepares hourly tide level predictions for the two permanent
stations, which can be obtained for any month of the year. (27,3Oi3l)

National Weather Service. The NWS. does not operate an
y tide gages of
its own in Connecticut. It does, however, obtain data from. the- NOS gage at
Bridgeport. The NWS, has installed a connection (Bristol Metameter)- to the
NOS ADR gage which transmits tide levels automatically to the Bridgeport WSO
by telephone, where they are, recorded on a continuous strip chart. The strip
charts are retained only a few months by the Bridgeport WSO, but daily high
and low tides and hourly tide levels are manually transferred from the strip
chart to printed forms, which are retained for several years. (32,33,34)

2-18

R-d.,

C" cylindw

M.-mete,

4.4

PIGS tube
Ik

FIGURE 2.10': Typical Bubbler Gage Installation

SOURCE: Bridgeport Weather Service office, Stratford, CT.

FIGURE 2.11: Typical Tide Record from Analog Recorder

2-19

Corps of Engineers/U.S. Geological Survey. Recording tide. gages are
also located in Stamford Harbor. These gages are owned by the COE for use
in conjunction with operation, of the Stamford Hurricane Barrier. The gages
are maintained by the USGS as part of a cooperative agreement. One gage is
located outside the hurricane barrier and another inside the barrier to record
differences in tide levels when the barrier is closed. Both are pressure

'
gages of the bubbler type, similar to the backup gages used by NOS. USGS
records the data at 15 minute intervals on punched paper tape. .The tape is'
collected by USGS personnel approximately every six weeks and processed for
inclusion in annual reports of water. records in C onnecticut. Unpublished
data are available at the USGS office in Hartford. Records are available
since October .1972. The COE records tide levels on a continuous strip -chart
within the station house. Charts are stored at the Stamford off ice for . three
years. The Stamford, gage is equipped with a Stevens Telemark unit which transmits
a coded tide level reading by telephone. The telephone number is unlisted,
and is used primarily by the. USGS and the. COE. NOS provides the COE with
predictions of hourly tide levels at Stamford Harbor. (25,35,36,37,38,39)

The COE used to operate tide gages. at Block Island and the Bridgewater
Lighthouse at Old Saybrook in an attempt to correlate tides and.storm surge
at those locations with tides and storm surge at Stamford, and to provide
increased warning time for operation of the hurricane barrier.. These gages
operated from approximately 1972 - 1977. Tide levels were recorded at three
hour intervals and did not record high and Jow tides. The COE found poor
correlation with the tide levels at Stamford, and because the gages offered
no prediction capability, they were removed. The data have not been retained.
(39,40)

U.S. Geological Survey/State of Connecticut. Under its cooperative agreement
with the State of Connecticut to collect streamf low, records, the USGS owns
and operates two water level gages in tidal locations: at the mouth of the
Poquonock River in Groton (Figure 2.6 (2)), and in Old Saybrook at the mouth
of the Connecticut River (Figure 2.6 (3)). Both gages are of the' bubbler
type and can record a 35 foot tidal range. In Old Saybrook, the gage is mounted
off the Saybrook Breakwater, and a digital recorder (punched paper tape) is
located in the Coast Guard's outer lighthouse. In Groton, the gage is mounted

2-20

off a pier, and both a digital and analog recorder are located in a former
Coast Guard building now owned by the University of Connecticut. Neither
of these two gages is equipped with a Telemark unit for 'remote transmission
of data. (36,37,38)

Records for the Poquonock River gage are available since January 1973,
and for the Connecticut River gage since October 1979 (data available from
June 1976 to February 1978 at a different location 0.6 miles north).@ The
USGS collects, maintains and publishes data from these two stations in the
same manner it does for the gage at Stamford Harbor. (35,36)

NOS Subordinate Stations, The long-term records of -the NOS stations
at New London, Bridgeport and Willets Point serve as reference marks for other
locations. At 38 "subordinate" locations along the Connecticut coast (and
7 on the north shore of Long Island), NOS installed temporary tide gages and
made simultaneous tide observations at the temporary station and either the
New London or Bridgeport permanent station (Table 2.2). The approximate time
and height of tides at each of these locations can be determined by using
the relationships developed by NOS. Included in' the NOS annual tide tables
is a tide table that provides the time and height relationship of each subordinate
stations to a primary station. (4,7,30,41)

La COASTAL IN CONNECTIQU

Flooding of coastal areas in Connecticut may result from both @coastal
and inland storms. Storms that deposit excessive rainfall over upland watersheds
may cause rivers and streams, to overflow in lowlying coastal areas. This
type of flooding may be particularly serious when'the peak flood runoff coincides
with high tide or storm surge that slows the discharge of floodwaters into
Long Island Sound, causing additional backup and overflow of floodwaters.
Lowlying areas right along the coast may be flooded directly by storm surge
and wave action.

2-2 1

POSITION DIFFERENCES RANGES,
Time Height Mean
NO. PLACE Lat. Long. Mean Spring Tide
high Low High Low Level
water water water water

h. h. 0. ft ft ft it ft
N W,

CONNECTICUT, Long Island Sound on NEW LONDON

1187 Stonington. Fishers Island Sound ........ 41 20 71 S4 -0 32 -0 41 *0.1 0.0 2.7 3.2 1.3
1189 Noank, Mystic River entrance ............ 41 19 71 59 -0 22 -0 08 -0-.3 0.0 2.3 2.7 1.2
1191 West Harbor, Fishers Island, M. T ....... 41 16 72 00 0 00 -0 06 -0.1 0.0 2.5 3.0 1.2
1192 Silver Eel Pond, Fishers Island, k. T ... 41 15 72 02 -0 16 -0 04 -0.3 0.0 2.3 2.7 1.1
Thames River
1193 NEW LONDON, State Pier .............. 41 22 72 06 Daily predictions 2 6 3 0 1 3
1195 Smith Cove entrance ................. 41 24 72 06 0 00 +0 10 -0.1 .0.0 2:5 3:0 1:2
1197 Norwich .............................. 41 31 72 05 +0 13 +0 25 +0.4 0.0 3.0 3@6 I.S
1199 Millstone Point .......................... 41 18 72 10 +0 09 +0 01 *0.1 0.0 2.7 3.2 1.3
Connecticut River
1200 Saybrook Jetty ...................... 41 16 72 21 +1 11 +0 45 *0.9 0.0 3.5 4.2 1.7
1201 Saybrook Point ...................... 41 17 72 21 +1 11 +0 53 *0.6 0.0 3.2 3.8 1.6
1202 Lyme, highway bridge ................ 41 19 72 21 -1 25 #1 10 +O.S 0.0 '@.I 3.7 1.5
1203 Essex ............................... 41 21 72 23 *1 39 +1 38 +0.4 0.0 3.0 3.6 1.5
Connecticut River
1204 Kadlyoe Ill.-- ..... 41 11 12 26 *2 19 -1 23 +0*1 0*0 1*7 3*1 1,3
1205 East Haddam ......................... 41 27 72 2e +2 42 +2 53 +0.3 0.0 2.9 3.5 1.4
1206 Haddam 0> .......................... 41 29 72 30 42 48 -3 08 -0.1 0.0 .2.S 3.0 1.2
1207 Higganum Creek ...................... 41 30 72 33 *2 55 +3 ?S 0.0 0.0 2.6 3.1 1.3
1209 Portland 0> ........................ 41 34 72 30 +3 51 +4 28 -0.4 0.0 2.2 2.6 1.1
1211 Rocky Hill 0> .... .................. 41 39 72 38 +4 44 45 44 -0.6 0.0 2.0 r2.4 1.0
1213 Hartford (7> ........................ 41 46 72 40 #5 30 +6 52 -0.7 0.0 1.9 2.3 1.0

on BRIDGEPOqT,

1214 Westbrook. Duck Island Roads 41 16 72 28 0 24 -0 32
0 :2:7 a 4 11 4 7 2
1215 Duck Island ................. 41 15 72 29 :0 26 - 35 2 3 00:0 4:S S:2 2:2
1217 Madison ............ 41 16 4.9 5.6
:.................... 72 36 -0 21 -0 30 -2.9 0.0 2.4
1219 F:lkneer Island. 41 13 72 39 -00 14 -0 25 -1.4 0.0 5.4 6.2 2.7
222 0 S ch a Need ......... 41 IS 72 42 - 12 -0 is -1.4 0.0 5.4 6.2 2.7
1221 Money Island ............................ 41 15 72 4S -0 12 -0 23 -1.2 0.0 5.6 6.4 2.8
1223 Branford Harbor ......................... 41 16 72 49 -0 08 -0 is -0.9 0.0 5.9 6.8 2.9
122S New Haven Harbor entrance ............... 41 14 72 SS -0 09 .-0 14 -0.6 0.0 6.2 7.1' 3.1
1227 New Maven (city dock) ................... 41 10 72 55 +0 01 -0 01 -0.8 0.0 6.0 6.9 3.0
1229 Milford 41 13 73 003 -00 0 -0 10 -0:2 0:0 6:6 7:6 3:3
123 1 Stratford, Nou 41 11 73 7 . 2: .1 Ol -1 3 0 0 5 S 6 3 2 7
2233 Shelton. Housatonic River ......... 41 19 73 05 +1 3S@ +2 44 -'-a 0.0 S.0 S.8 2.5
1235 BRIDGEPORT ........................ :::::: 4110 73 11 Da ily predictions 6.8 7.7 3.4
1237 Black Rock Harbor entrance .............. 41 09 73 13 -0 04 -0 03 +0.1 0.0 6.9 7.9 3.4
2239 Saugatuck River entrance .......... ..... 41 06 73 22 -0 02 +0 01 +0.2 0.0 7.0 8.0 3.S
1241 South Norwalk .....................: ..... 41 06 73 2S +0 09 +0 15 40.3 O.'V 7.1 8.2 3.S
1243 Gre en ,Led 9e .......... .................. 41 03 73 27 -0 02 -0 01 *0.4 0.6 7.2 8.3 3.6
124S Stamford .................................. 41 02 73 33 +0 03 40 08 +0.4 0.0 7.2 8.3 3.6
1247 Cos Cob Harbor .......................... 41 01 73 36 +0 OS +0 11 *0.4 0.0 7.2 8.3 3.6
1249 Greenwich ............................... 41 01 73 37 +0 01 *0 01 +0.6 0.0 7.4 B.S 3.7
1251 Great Captain Island ..................... 40 69 73 37 a 00 +0 01 40.S 0.0 7.3 8.4 3.6

NEW YORK on.WILLETS POINT.
Long Island Sound. North Side

12S3 Port Chester ............................ 42 00 73 40 -0 03 .0 14 40.1 0.0 7.2 B.S 3.6
1254 Rye Beach.@ .............................. 40 58 73 40 -0 22 .0 31 *0.1 0.0 7.2 8.4, 3.6
12SS N:mar n:ck 100 S1 13 41 -0 02
:0 13 -0:2 0 1, 6
0:00 7:1 1: 3:
12S7 k . R:c 4 54 73 47 - is 0 19 *0 1 7 2 a6 3 6
1259 Davids Island ........................... 40 53 73 46 #0 04 -0 09 +0.1 0.0 7.2 6.5 3.6
1261 City Island ............................. 40 51 73 47 +0 03 -0 Os 40.1 0.0 7.2 9.5 3.6
1263 Throgs Neck ............................. 40 48 73 48 *0 08 +0 12 -0.1 0.0 7.0 6.2 3.5

SOURCE: National'Oceah Service. 1984. Tide Tables4 1985 High and Low
Water Predictions, East Coast of North and South America, Including
Greenland. NOAA, U.S. Dept. of Commerce.

TABL E 2.2: National Ocean Survey Subordinate Tide Gage Locations
in Long Island Sound, Showing Tidal Differences and
Other Constants

2-22

2AU Hurricanea and Tropical Storms (Tropical Cyclones)

The term tropical cyclone applies to atmospheric systems which develop
in the tropical and subtropical zones and have a counterclockwise rotation
of winds (in the northern hemisphere), with the lowest barometric pressure
located at th e center of the vortex. To develop, they require surface water
temperatures above about 26 C (79 F), and are maintained by energy from.conden-
sation of water vapor drawn from the warm ocean surface. Consequently, most
tropical cyclones- occur in August, September and October (the official tropical
cyclone season is from June 1 through November 30). They dissipate quickly
as they pass over land masses or cold water and are deprived of the warm,
moist air that supplies energy.

Tropical cyclones range in diameter from 50 to more than 500 miles.
Several categories of tropical cyclones are recognized according to their
intensity and degree of o rganization:

(1) tropical disturbance (little or no rotary circulation at the surface
and no strong winds);

(2) tropical depression (winds equal to or less than 38 mph);

(3) tropical storm (winds of 39 mph or more); and

(4) hurricane (winds of 75 mph or more).

Tropical storms and hurricanes are of major concern as causes of severe
coastal flooding. Hurricanes are further divided into five categories (Saffir/
Simpson Hurricane Scale) according to their central pressure and maximum sustained
winds (Table 2.3).

In hurricanes, atmospheric pressure and wind speed increase rapidly with
distance outward from the center, or eye, of the storm (not necessarily the
geometric center) to a zone of maximum.wind speed which may be anywhere from
4 to 60 nautical miles from the center. From the zone of maximum wind to
the edge of the hurricane, pressure continues to increase, but wind speed
decreases. The atmospheric pressure within the eye (central pressure index)

2-23

CATBGORY CENTRAL PRESSURE WINDS
(Inches Mercury) (mph)

1 >28.94 74-95
2 .28.50-28.93 96-110
3 27.89-28.49 111-130

4 27.18-27.88 131-155

5 <27.17 >155

TABLE 2.3: SAFFIREISIMPSON HURRICANE SCALE

is the best single index for estimating the surge potential' of a @hurricane.
Hurricanes may also be characterized by the radiu's of maximum winds, which
is an index of the size of the storm, and the speed of forward motion of the,
storm.

The path of an individual storm is determined by its. point of origin,
and by the relative position and strength of low and high pressure centers
located in the westerly wind belt and over the Atlantic Ocean. From 1886-1985
nine hurricanes (including Hurricane -Gloria in September 1985) have passed
over or near Long Island Sound (50 mile, radius of the center of Long Island).
The tracks of six selected hurricanes are. shown in Figure 2.12. During this
same period, 15 tropical storms have hit the area. The tracks of all hurricanes
and tropical 'storms are shown in Figure 2.13. Prediction of the path which
a pa rticular hurricane or tropical storm'@will take is very. imprecise. (11,42, 43)

Utilizing statistical data on the motion of tropical storms in t.he Atlantic
area, Neumann a .nd Pryslak (44) calculated the expected number of tropical
storms and hurricanes per 100-year period impacting locations along the U.S. coast-
line. Figure 2.14* shows the grids that encompass the Connecticut coastline.
The data in Figure 2.14 show that tropical storm occurrence in Grid 518, which
includes. the eastern portion of Long Island --Sound, is greater than in Grid
517, which includes the western part of, the Sound. Based on actual tropical
storm occurrence and movement data, the expected number of tropical storms

2-24

74. 70, er to-

23 SEPT. 1815
CAROL!
11 AUG. 1954 'IDONNA'
12-13 SEPT. Igoe

NEW

DRUM SWI C`X

21 SEPT 1936

14-15 SEPT 1944@

tM A I N E
...East

LOR4A"
2-7 sepr. i9w&S

44.

bs-
A S S.

OF
R. L
1c, N

j SOURCE: Adapted from Corps of Engineers, New England
Division. 1982. Regulations Manual, Stamford
Hurricane Barrier, Stamford, CT. Corps of
Engineers, Dept. of the Army.

FIGURE 2.12: Tracks of Seven Selected Hurricanes Crossing
or Approaching Long Island Sound

2-25

0
12

40 Storm Starting Sto;m Starting 40
Track I Date Name Track 0 Date Name
1 6/1811886 - 12 9/1011938 -
2 8/1411888 - 13 91911944 -
3 9/611888 - 14 10112/1944 -
4 10/8/1888 - 15 8125/1954 Carol
5 8/1511893 - 16 8/7/1955 Diane
6 101111894 - .17 7/28/1960 Brenda
7 9/2011897 - 18 8/2911960 Donna
8 10/811900 - 19 911211961 -
9 - 20 8120/1971 Doria
10 6/411934 21 6/14/1972 A@nes
1 22 11 915/1934 - 22 8/6/1976 Belle
23 9/27/86 Gloria
35
so 75 70 65 60

SOURCE: Adapted from Long Island Regional Planning- Board. 1984. Hurricane
Damage Mitigation Plan for the South Shore of Nassau and Suffolk
Counties, New York- Long Island Regional Planning Board,
Hauppauge, NY.

FIGURE 2.13: -Tropical Storms and Hurricanes Passing
Near Long Island Sound

Grid 517 Grid 518
Massachusetts

new

York
rh
connecticut islanS

new
Probability Probability Of 0.
jersey Expected Me. Expected Of At Least At Least Orw
of Tropical Nb. of On@ Tropical Hurricane
stormalloo Hurricanoof Stem Over a Over A
row 44 Grid Years 100 Years 10 Year Period '10 Year Period
19 7 0.85 0.50

31 18 0." 0.00
F5 -,a I - I
Emommum I I

SOURCE: Neumann, C.J. and M.J. Pryslak. 1981. Frequency and Motion of
Atlantic Tropical Cyclones. NOAA Tecbnical Report NWS 26. National
Hurricane Center, Coral Gables, FL..

FIGURE 2.14: Expected Number of Tropical Storms and Hurricanes
per 100 Years Impacting the Long Island Sound Region
:C]

2-27

entering Grid 518 per 100 years is 31; 16 of these storms would be hurricanes.'
In Grid 517, 19 tropical. storms per 100 years would be expected, of which
seven would be hurricanes. The probability that at least one tropical storm
will impact the Connecticut coastline over the next 10 years ranges from 0.85
to 0.96. The probabilities that at least one hurricane will impact this area
over the next 10 years are slightly less, ranging from 0.50 to'0.80. (45)

Since hurricane winds move -in. a counterclockwise spiral, the winds 'in
the right quadrants of this spiral are more or less parallel with, and reinforced
by, the translational (forward) movement of the storm. . This reinforcement
can be of considerable magnitude, as hurricanes have travelled at forward
speeds of over 50 kn bts. The Winds to the left of the storm track are weaker
than those to the right, because the winds blow' in directions opposite to
the translational movement of the storm. Consequent ly, winds and 'storm surge
are normally at a maximum in. the northeast @ quadrant of hurricanes. (11,42,43)

South-facing coasts, like Connect icut's, that are aligned perpendicular
to most storm, tracks, receive the full impact of -the reinforced winds. and
wave set-up. Howeve r, Long Island Sound and Connecticut are somewhat protected
-by Long Island, which blocks ocean--generated waves from reaching most of the
Connecticut coast, and which may cause a hurricane to weaken as it passes
over the colder land mass.' In general, fast moving hurricanes have peak storm
surges that are. higher than slower moving storms. However, slower moving
storms can cause a higher surge in estuarine areas, such as Long Island Sound,
because there is more time for water to flow into the Sound. (11,45)

Figures B.1 and B.2 (Appendix,B) display data on actual storm surge levels
recorded during the 1938 and 1954' hurricanes, along with projected storm surge
profiles for 100, 50 and 10-year frequencies (6,46). The 100-year flood prof ile
shows the highest flood level in western Connecticut' (12.2 feet NGVD)9 lowering
to 10 feet by Stratford. From Stratford east the level rises to about 10.7
feet at East Haven, followed by a gradual decrease to about 10.0 feet at Waterford.
At New London the level is 10.0 feet NGVD. To. the east, of New London the
fl ood level increases from about 10.0 feet to 10.8 feet at Stonington.
Storm surge is seen to increase dramatically within -the Thames River
Estuary. According to the COE 1980 (12) study, storm surge increased from

2-28

9.5 feet to 14.3 feet NGVD at the 100-year level as the distance from the
mouth of the Thames increased. The 1938 hurricane surge ranged from 9.8 feet
at New London up to 15.2 feet in Norwich. Figure 2.15 shows tidal surges
compared to the predicted normal tide levels at Stamford Harbor for the 1938,
1944 and 1954 hurricanes. (47)

2.51Z EXtratropical Storms

Extratropical storms are weather s ystems that develop in mid-latitudes
in the fall, winter and spring (most commonly November through April), in
response to the interaction of warm and cool air masses along a weather front.
They occur much more frequently than tropical cyclones, and may be more than
1000 miles in diameter -- two or three times the size of a tropical cyclone.
Extratropicall storms also form a counterclockwise spiral directed toward a
center of low barometric pressure, but the maximum winds are of lower velocity
than tro pical cyclone winds. Some gusts of hurricane velocity may occur with
extratropical storms.

Extratropical storms that occur along the northern part of the east coast
of the U.S. accompanied by strong winds blowing from the northeast quadrant
are called. northeasters. Northeasters may s tall off the southeast coast
of New E ngland and produce high tides that persist for several days. An example
of this is the storm of October 1955 when high tides continued from 14-16
October. (11,45,48)

A study of northeasters affecting the Atlantic coastal margin of the
United States during the period 1921-1962 (48) found that during the 42 year
period of record, 34 extratropical storm events occurred that resulted in
water-related damage, i.e., damage due to wave action and tidal flooding.
The recurrence interval of such storm events is 1.24 years. Stated in another
way, a storm of this nature has an 81% chance of occurrence in a given year,
based on the observed data.(45)

Wind directions from extratropical storms at a particular area depend
on the relative position of the storm track When a storm center passes to

HURRICANE WE 0
ME

E L. 5.2'

POOL -LEV.

I 1 -0, %L I
EL. 3. 3, Of FAST BRANCH
POOL ELf
rAsr oRANav
MCI. ELEV.

t--PftEDtcrEa NDE 4__,RED1creo rIDE

WAN SEA LtVft--_
OF

CA O$rV We. CLOSED
CLOSED
_141A@ 6PK SPN. IOPK 1Z TADT 2 A K 84,M. OA M, 1z woo" 2
EASTER N 8 T A N D A R 0 T I M E

21 SEPTEMBER 1938 14-15 SEPTEMBER 1944 31 AUGUST 1954

NOTEI NOTE: NOTE:

1.* 0 willq ftit. N., .0 &4#ww, .,..p Vaek'o Mkv
ft-/Y ra" Pwd..f'_ bt.t . 0-0 '958 C_.' Mftrd 1. V.-ftt
r", 6wo 0".1- d'
I.C.10.1f .1 affaw" Y.1k. .1h ft."Caft IM hftey '01"ta .? 8"0#.P.F'

SOURCE: New England Division. 1982. Regulation Manual, Stamford Hurricane
Barrier, Stamford, Connecticut. U.S. Corps of Engineers, Waltham, MA..

FIGURE 2.15: Selected.Storm Surges at Stamfor d Harbor, Stamford, Connect

2-30

the wes t of Connecticut, winds blow initially from the east or southeast.
As storm movement progresses, the winds shift to south and then west. This
type of storm results in onshore winds, leading to increased wave height and
wind set up. If, on the other hand, the storm center passes to the east of
Connecticut, the initial winds will blow from the northeast. Later the winds
will veer to the north and northwest. This type of storm produces offshore
winds and a smaller storm surge due to reduced effects of waves and wind set
up. (45)

The effect of northeasters on shoreline areas often depends on their
speed of forward movement. If the storm progresses rapidly, variable wind
directions over a given fetch length prevent the buildup of large storm waves.
However, if storm progress is delayed by ridges of high pressure, winds from
a particular direction have time enough to act on a given wave group, to produce
waves of maximum height for a specific wind velocity and fetch. Prolonged
wave action during successive high tides can lead to erosion and damage to
shoreline development. (45)

Mapping of Coastal Floodplains

Coastal areas (a*s well as riverine floodplains) subject to flooding have
been identified on Flood, Insurance' Rate Maps (FIRMs) prepared by FEMA and
its contractors. These FIRMs delineate areas with a one percent or greater
chance of being flooded each year (commonly referred to as the one-percent
f lood, 100-year flood and base flood). The 1938 hurricane produced flooding
approximately equal to the one-percent flood over much of the Connecticut
coastline (see Figure B.1).

Coastal floodplains subject to damaging wave action (waves three feet
or higher) are designated on FIRMs as V-zones3. Areas subject to flooding
from storm surge, but with no wave action or waves less than three feet, are

3A three-foot high wave was selected for determination of the V-zon e based
on data compiled by the COE, which indicated that a three-foot wave was capable
of causing structural damage. (51)

2-il

designated as A-zones. (49,50,51) Figure 2.16- shows a portion of the coastal
floodplain in the Town of Milford as delineated on a recently adopted FIRM.

FIRMs provide a good basis for designating areas subject to floodplain
regulations and flood-related building code requirements. However, because
the different flood zones delineated on FIRMs have not been correlated with
particular storm characteristics, these maps cannot be used to acurately estimate
which areas will be flooded 'during a developing hurricane or other storm.
Nevertheless, they provide the only information presently available on which
to base evacuation notices in coastal areas.

2..5A Flood Dam&=

Five hurricanes. (including Gloria in 1985) and several nortbeasters have,
caused damaging coastal flooding An this century. The hurricanes of 1938,,
1944 and' 1954 caused the most damage. Unfortunately, very limited information
is avai lable on the dollar amount of damages caused by these. and other storms,
particularly the smaller storms. In 1976 the COE estimated. that, in 1975
dollars, a recurrence of the 1938 hurricane would cost $111,500,000 in losses
from tidal flooding, and.a recurrence of the 1954 hurricane would cause losses
of $72,0'00,000. (12) No. updated estimate has been made since that time.
However, it is likely that due to increased development along the coast, the
losses in 1985 would be more than double the amount estimated in 1976.@ As
an indication of the amount of property at risk, Table 2.4 lists the number
of structures located in V-Zones for each of the coastal towns. (52)

2-32

KEY TO MAP ZONE
$WVm r lood BooMmy B
lwv- I " B-Am' COASTAL BASE FLOOD ELEVATIONS
I- Dopmloo.- W 1 APPLY ONLY LANDWARD OF THE
SHJRELINE SHOWN ON THIS MAP.

IUD Yom F@
SWV- I lood B-mdv
0- 1 - I k."- L'oo
wah ILI--- 1. f I..
am, .1.1 MI. 987)
Who,, W.1hi, Imo- @0
LkIlliom 110 ...... M.& RM7X
X,
Rv&.' M'.

--Rd
d 1. 11m Na@ Gtolom, Vo-J 0-1 a 1929 VL
UE
-EXPLANATION OF ZONE DESIGNATIONS

IONS EXPLANATION
A Mo. W 100-, floool; b- 6.4 k-i- -d
floml @.d I= .. d.-oml.
AO A,m ad 10 *Aom Itodow whom dpft
IN, ww da.. 3j..'. _'w dopo.
Om.., flood I-ool I- z BAY.
_
.U-,L
k-
AN A.. ol 100-1 @AW. II.W.8 oo. OWOo
wo tm- om, (I I mul thoo, 13) fni; boo flood
,loudoos me sloo,on, low sm Uwd hmmd I-
doe-ioet ZONE
41-AM A,- of 10&- 11.0; 6mo fi-W Wimn mod lkli B
floool hmad Imlon Uftmomwd.
AN A,- W lQOv- floml Im bo Pm,Mc ed DV Iked
o,olm boo Ilmod 'A
do.o.- -d Wool hood I--- moo dm-wol.
If Also Imloom fienift of IM IODvm food a" 500-
W.. lk*d; . -@ mom, N.. . 2011@vow F-d.
N, .10 -qp dopft k. Ihm ow 4 1) k- . h- T,
tho cW*W.S d,..W mo. I. No lkwo - =
..; . moo ciallbVisoonfroadmime n@
boo d-M.Ki
C A,- of minimai floodiall. iflohadw4l
0 Alm of mmilautob". boo Powiloo. flimool lm@omd&
v ". .1 100@- comial Good Mo olmAv I.-
w1w); boo nwo 'b"Alwo a" now hood fogooi
- d.._mmL
V1420 A... of 100@y- -1ol Flood I* Ikv
NmL
oldb 0.0 olwd- mod "U..W k.-.d I.-

NOTES TO USER

m- mo Im om mmm-dmom4amn Amod VI
mo b. WoMebod bV Road go*UW UPKIMNI6
0 0
Tbi. NoP I& lot flood I--- Powomo, odr; It dm omi oo,m,
..'my doo. A no. subim so flooolog I. doo cowwoMly or
plawkwok I-um cooh W@W flood bumd w-. 0
I. mlPows map pmvd@ " "Pameliv Pdowd ftwoo To map
P..&
Lom,a " Rood dm4dw Ibino cm Nok mv looloin 0, P;,
Co." boo flood W.A1001 Nolft MV 1100.0111 .9 No 0holl-
foo_ mo Mb
dk_

INITIAL IDENTIFICATION: Y

ONE B
FLOOD IRAZARD BOUNDARY MAP RAVISIONS: ONE B

FLOOD INSURANCE *AVE MAP EFFECTIVE: L
N'll
IlkV11,901%, 00
J;Nll I
AV( Nl)!,,@
42
'<@A @@Ci;
L'r
r
41 I@ I--- _lAA` . 1h. -ooft'. Ift
Flowl lm-
IX) 614 "20.

SOURCE: National Fl ood Insurance Program, Federal
Emergency Management Agency. 1983.
Flood Insurance Rate Map (Panel 6),
APPROXIMATE SCALE City of Milford, Connecticut.

FIGURE 2.16: FEMA Flood Insurance Rate Map for
Section of Milford, Connecticut

2-33

Residential Commercial/Industrial Total

.Greenwich 207 1 208
Stamford 10 0 10
Darien 125 1 126
Norwalk 145 2 147
Westport 275 0 275
Fairfield 98 i 100
Bridgeport 24 3 27
Stratford 229 16 245
Milford 615 8 623
West Haven 240 6 246
New Haven 50 1 51
East.Haven 349 4 353
Branford 388 3 391
Guilford 174 0 174
Madison 270 5 275
Clinton 95 0 95
Westbrook 126 0 126
Old Saybrook. 234 1 235.
Old Lyme 131 1 132
East Lyme 4 1 5
Waterford 12 0 12
New London 35 13 48
Groton 16 6 22
Stonington 15 0 is

TOTAL 3,867 74 3,937

SOURCE:. Rummel, Cyn thia J., and G.J. Hudak. 1984-1985. Flood Vulnerability
Assessment (for 24 coastal Connecticut municipalities). Natural
Resources Center, Department of Environmental Protection,
Hartford, CT.

TABLE 2.4: Structures Located in V-Zones

3-1

OOD
_0 FT. FORECASTS AND WARNINGS IN CONNECTICUT

The procedures used by federal, state and local governments to *prepare
and disseminate coastal flood forecasts and warnings must be understood in
order to evaluate the feasibility of developing an improved flood warning
system.

11. RIVERINE FLOOD FORECASTS AND-WARNINGS

Although a coastal flood monitoring network and warning -system would
not be comparable in all respects to an automated riverine flood forecasting
and warning system, a coastal system would share many similarities. It was
the development of an automated riverine flood warning system for Connecticut
that led State officials to consider the possibility of also establishing
a compatible. coastal flood monitoring network and warning system. (53)

ad.1 National Weather Service ALERT Syste

For years the NWS has maintained cooperative flood warning systems in
many communities through out the U.S. These cooperative systems rely, upon
a network of community vol unteers to make regular observations of rainfall
and/or river levels and to telephone their observations to the appropriate.
NWS office, The NWS uses the data gathered by the volunteers, along with
its own data on soil moisture conditions and precipitation forecasts, to run
a hydrological model of the river basin and predict the time and level of
flooding. While very effective in some communities, these programs'have inherent
limitations. Most notably, observers ar e not always available to collect
and report -data on precipitation and river levels, particularly during@ the
night and at remote. locations.

In recognition. of these limitiations, in the late 1970's the NWS began
developing an automated flood warning system. The automated system was designed
to take advantage of technological advances that permit real-time collection

3-2

and transmittal of meteorological and hydrological data from. remote locations
to populated areas with people and property at risk.

The resulting system was called ALERT (Automated Local Evaluation in
Real Time). The ALERT system does not rely upon volunteer observers; it is
entirely automated. The major components of the ALERT system are: precipi-
tation gages, river gages, radio transmitters, radio receivers, data encoders
and decoders, a microcomputer, and specially designed software to process
the data. Remote rain gages automatically collect data on amounts and rates
of rainfall and transmit this information via VHF radio to a base station.
Similarily, stream gage stations transmit. data on the rise in river levels.
Generally, data collection and transmittal from remote locations is battery
powered. Because the system is designed for "event reporting" (data transmitted
only when there is a predetermined amount of rainfall or change in stream
level), batteries can last a year or more without recharging.

.When predetermined critical precipitation and/or stream level values
are reached, an alarm is triggered at the base stations and personnel are
placed -on alert to monitor the situation closely. Using the rainfall and
river rise information, combined with precipitation forecasts and a hydrologic
model of the stream, NWS personnel are able to accurately forecast floods
and provide. downstream officials and residents with increased warning time.
Since the information is also received at a local base station, local officials
can, if necessary, initiate flood warnings without, waiting for a forecast
from the NWS. . The increase in warning time afforded by the automated system
is often sufficient to permit emergency actions which can save lives and greatly
reduce p roperty losses.

ALERT systems were initially used in the western US where sudden rainstorms
in the remote, upper portions of watersheds can cause flash floods in lower
portions of the watershed where no rain may have fallen. ALERT systems have
now been, successfully installed in more than two dozen locations throughout
the U.S., and many more are now under development. The original ALERT system
was developed by the NWS, but several private firms have now developed similar
systems.. ALERT type systems have found wide acceptance on large and remote
river basins in countries other than the U.S. (54955,56957,58959,60961962)

3-3

Connecticut Automated Flood Warning S@stem
In '1982 Connecticut and NWS officials began examining the possibility
of a statewide automated flood warning system for small watersheds subject
to flash floods. An interagency Committee on Automated Flood Warning (CAFW)
was established to oversee development of the statewide system. Particularly
important to CAFW was the technical assistance provided by the NWS and technical
and financial assistance from the Soil Conservation Service (SCS).

A statewide system was designed in 1983 and called ASERT (Automated State
Evaluation in Real Time). ASERT is in-tended to be operated in cooperation
with local communities, and the combined system. is sometimes referred to as
ASERVALERT' The initial phase of the A.SERT system is now being installed
and consists of 20 automated rain gages, 6 weather stations (including precipi-
tation gages)9 6 radio signal repeaters, and 2 base stations. Each base station
includes a radio receiver, data. decoder, microcomputer, ALERT software, and
an uninterruptable power supply backup. The base stations are located at
the Northeast River Forecast Center (NERFC) in Bloomfield and the DEP offices
(Water Resources Unit) in Hartford.

Concurrently with installation of the ASERT system, community ALERT systems
are being installed on a 'pilot basis in the City of Norwich (Yantic River
basin) and the Town of Southington (Quinnipiac River basin). Each. ALERT
system includes an automated river gage and a base station. The City of Stamford
has also installed its own ALERT system (63).

The initial ASERVALERT system should be operational in 1986, and the
State expects the, system, to be expanded into other river basins as local commun-
ities recognize the benefits of the program. CAFW has prepared a master plan
tha t projects an additional 85 precipitation gages, 24 repeaters, 40 river.
gages, and 28 base stations will be added to the system over the next 10 years.
This system design may change as CAFW continues its work and experience with
the initial installations is obtained. Important aspects of the ASERT system
that are still evolving include procedures for archiving data and providing
maintenance.

3-4

The CAFW master plan also includes a coastal component. The purpose
of this present study is to design the coastal monitoring network and evaluate
the feasibility of a coastal w*arning system as part of the ASERT/ALERT system.
Specifications for the ASERT components that may be used by the coastal network
are provided in Appendix A. (53,64,65,66,67)

COASTAL FORECASTS AND WARNINGS FOR CONNECTICUT AND LIS

Currently, all official weather forecasts (including storm surge and
wave heights) and coastal flood warnings for Connecticut and Long Island Sound
are provided by the NWS. The procedures used by NWS for preparing these forecasts
and warnings and then disseminating them to other units of government and
to the public are described in the following sections.

NWS Procedures

Different NWS offices are involved with forecasts and warnings. depending
upon the type of weather system and flood component involved.
Forecasts and warnings for coastal Connecticut can be complicated because
the Connecticut shorelin e forms. the border between the areas served by the
Boston Weather Service Forecast Office (WSFO) and the New York WSFO. (32,68,69,75)

MARINE WEATHER FORECASTS AND WARNINGS The New York WSFO is responsible for
marine forecasts and warnings for LIS, to Watch Hill, Rhode Island and Montauk
Point on.L"ong Island. The Bridge Iport WSO prepares marine bulletins for Fairfield,
New Haven and Middlesex counties using the New York WSFO forecast supplemented
with information.on local conditions. The Hartford WSO prepares similar bulletins
for New London County. Marine weather bulletins are routinely issued over
NOAA VHF-FM Weather Radio (162.400 MHz, Meriden; 162.475 MHz, Hartford; and
162.55 MHz, New London and.New York). These same weather bulletins are transmitted

1
The Boston WSFO is responsible for forecasts and warnings for the New,England
area, including all land areas of Connecticut. Wind forecasts by Boston WSFO
for Connecticut and by New York WSFO for LIS sometimes differ, requiring consul-
tation among the New York and Boston WSFOs and the Bridgeport and Hartford
WSOs. (32,68975)

3-5

over the NWS teletype to selected government agencies and print and broadcast
media. -In addition to-NWS teletype and NOAA Weather Rad io, warnings of severe
weather conditions, including flood watches and warnings, are issued over
the National Warning System (NAWAS).

NWS off ices' at Bridgeport, and New York can be telephoned to receive
the latest marine forecast or warning. Every six hours, the Bridgeport WSO
7
prepares an.updated tape of marine forecasts and warnings, including a report
on local weather conditions -at the Bridgeport WSO. If the Bridgeport WSO
observes local conditions significantly different from the marine forecast
issued by. New York WSFO, it contacts the New York WSFO. The Coast Guard stations
at New Haven and New London also broadcast NWS marine forecasts and warnings
over its ...radio frequencies, and maintain day and night visual warnings for
mariners at several locations along the Connecticut coast. (15v32,68,69970,76)

WAVE HEIGHT FORECASTS Forecasts of wave heights are developed- by the New
York WSFO, which has forecast responsibility from Watch Hill, RI to Manasquan,
NJ, including Long Island Sound west of Watch Hill. These forecasts are made
rout*inely every six hours for use in the LIS marine -forecast. The forecasts
of wind waves are prepared using information on present wind speed, wind duration,
and fetch length, or,forecast wind speed. According to information supplied
by the New York WSFO, it uses at least two sets of wind wave forecast charts,
both of which were developed for predicting waves in open seas2. In applying
these procedures to wave forecasts in LIS, the meteorologists make adjustments
based on their experience. Information on wind speed which Js used in the
wave'forecasts is obtained from meteorological instruments along the Connecticut
shore. (Bridgeport, New. Haven airport, Groton airport), at several locations
on Long Island (La Guardia airport, Islip airport, Farmingdale airport, Suffolk.
airport, Plum* Island, and Montauk Point), and from reports -of ships at sea.
The wave height forecasts are intended for mariners and reflect average wave
conditions in open coastal waters. They are not intended to indicate breaking
wave heights in coastal areas. (20,32,69,74,145)

2
See Section 4.1.2 and Appendix B for a discussion of wave, forecasting/ bind-
casting models.

3-6

EXTRATROPICAL STORMS Weather forecasts for extratropical storms are prepared
by the New York WSFO for LIS and by the Boston WSFO for inland Connecticut.
Both the New York and Boston WSFOs use data and forecast guidance from the
NWS National Meteorological Center (NMC) in Silver Springs, Maryland. (15,71,72,75)

Using an automated statistical model, the NMC prepares storm surge forecasts
twice daily, projected for a 48-hour period. This information is provided
to the regional WSFO, at New York City as guidance (Figure 3.1). The New York
WSFO may modify the forecast, if needed, based on observations of local conditions
and using a manual version of the statistical storm surge modeI3. The New
York WSFO, receives reports of actual storm surge conditions from the Bridgeport
WSO (every 6 hours) and from four stations in New York Harbor (every 6 minutes),
which may be used in revising storm surge forecasts. (15,71,73)

There is no established procedure for verifying the accuracy of storm
surge or wave forecasts. There is no instrumentation to record actual wave
heights and no systematic observations of wave heights are made.(20,32)

HURRICANES T he National Hurricane Center (NHC) in Coral Gables, Florida issues
all forecasts and storm warnings for hurricanes, including storm surge forecasts
generated, by a numerical model called SLOSH (Sea, Lake and Overland Surges
from Hurricanes). A separate wave height forecast is not prepared for hurricanes
since the SLOSH4 model indirectly incorporates waves into its storm surge
prediction. NWS Regional WSFOs and local WSOs do not modify the NHC forecasts
and warnings, although they may supplement them with up-to-date reports on
local conditions, including wave heights, and provide additional warnings
for particular geographic areas. Local weather conditions are provided to
the NHC over a Hurricane Hotline by NWS offices in the affected areas, and
used by the. NHC is developing its hurricane forecast. (20932,68,69,72)

3See Section 4.1.1 and Appendix B for a discussion of the NWS storm surge
models for extratropical storms.

4
See Section 4.1 and Appendix,B for more complete descriptions of the SLOSH
model.

3-7

FZUS3 KWBC 021200
STORM SURGE FCST FEET INVALID FOR TROPICAL STORMS

12Z 18Z OOZ 06Z 12Z 157, OOZ '06Z 12Z
PwM 0.1 0.4 0.5 0.7 0.7 0.9 0.8 0.9 0.7
BOS 0.1 -0.2. 0.3 0.4 0.4, 0.5 0.4 0.6 0.3
NWP 0.8 1.0 1.1 1.2 1.2 1.3 1.1 1-1 0-9
S FD 1.0 1.1 1.2 1.2 0.9 0.7 0.6 0.1 0.0
LGA 1-0 1.0 1.0 1.3 1.2 1.0 1-0 0.8 0.7
NYC 1.2 1.3 1.4 1.4 1.3 1.2 1.0 0.9 0.7
ACY 0.8 0.9 1.0 0.9 0.9 0.9 0.8 o.8 0.7
BWH 1.1 1.1 1.2 1.0 OA 0.9 0.7 0.7 0.6
BAL 2-4- 2.5 2.6 2.8 2.8 2.6 2.4 2.0 1.9
ORP 0.9 o.8 o.9 o.8 o.8 o.8 0.7 o.6 o.9

PWM Portland,.Maine
.BOS Boston, Massachusetts
NWP Newport, Rhode Island
SFD Stamfordj. Connecticut
LGA Willets Point, New York.,
NYC New York, New York
ACY Atlantic City, New Jersey
BWH- Breakwater Harbor, Delaware
BAL. Bal 'timore, Maryland
ORF Hampton Roads, Virginia

(Note: Forecast time in 24 hour time.)

SOURCE: Pore, N.A., et. al. 1974. Forecasting Extratropical Storm Surges
for the Northeast Coast of the U.S. NOAA Technical Memorandum
NWS.TDL-50. Washington, D.C.

FIGURE 3.1: Sample Storm Surge Forecast Guidance:. Teletype Message
to Weather Service Forecast Offices

3-8

Hurricane forecasts are u pdated by the NHC every six hours. Forecast
preparation is initiated at 2 am, 8 am, 2 pm, and 8 pm EDT. When Hurricane
Watches or Warnings5 are not in effect, Public Advisories based on these forecasts
are issued at 6 am, Noon, 6 pm, and 10:30 pm EDT6. Once the NHC issues a
Watch or Warning for a particular area, Public Advisories are issued every
three hours, and the 6 am, Noon, 6 pm and Midnight EDT advisories are based
on the new forecasts.

Public Advisories include: an updated report on the position and track
of the hurricane, forecast position, barometric pressure at the center, maximum
sustained winds, wind,gusts, areas subject to a Hurricane Watch or Warning,
the predicted wind speeds and storm surge expected in those areas, and the
probability of the hurricane reaching landfall at specific locations. Forecast
positions are given for 12, 24t 369 48, and 72 hours beyond the time the forecast
is made.

Beginning with the 1983 hurricane season, the NHC began including in
the Advisory the probability of the hurricane reaching landfall at specific
locations. Probabilities are defined as the chance in percent that the center
of the storm will pass within approximately 65 miles of a stated location.
Probabilities are issued in tabular form, as shown in Figure 3.2. (77)

As was shown clearly during Hurricane Gloria, the NHC, as well as regional
and local NWS offices, provide close coordination with local T.V. and radio
stations serving areas within the projected track of a hurricane.

TROPICAL STORMS @-.The RHC also prepares forecasts and warnings for tropical
storms, and uses the SLOSH model to predict storm surges generated by tropical
storms. As with hurricanes, no separate wave height is predicted. The New
York WSFO may modify.the tropical storm forecast and warning for LIS based

5A Hurricane Iyatch is issued for a coastal area when there is a threat of hurricane
conditions within 24-36 hours. A Hurricane Warning is issued when hurricane
conditions are expectd in a specified coastal area in 24'hours or less. (77)

6
Except for the 10:30 pm advisory, the forecast preparation begins four hours
before the advisory time. The 10:30 pm advisory is issued earlier in order
that it may, be available for the evening television news broadcast. (77)

MIATCPAT3 ADVISORY NUMBER 48 HURRICANE GLORIA PROBABILITIES
TTAA88 XNHC 262136 FOR GUIDANCE IN HURRICANE PROTECTION PLANNING
BULLETIN BY GOVERNMENT AND DISASTER OFFICIALS
HURRICANE GLORIA ADVISORY NUMBER 48
NATIONAL LEATHER SERVICE MIAMI FL CHANCES OF CENTER OF GLORIA PASSING UITHIN 65 MILES 0
6 PM EDT THU SEP 26-1985 LISTED LOCATIONS THROUGH 2 PM EDT SUN SEP 29 1985

UPGRADE GALE WARNINGS TO-HURRICANE WARNINGS MOM OF CAPE HENRY TO CHANCESI EXPRESSED IN PER CENT'...TIMES EDT
PLYMOUTH MASSACHUSETTS INCLUDING CAPE COD. A HURRICANE WATCH IS IN ADDITIONAL PROBABILITIES
EFFECT NORTH OF PLYMOUTH THROUGH EASTPORT rAIME. 2 PM FRI 2 AM SAT 2 PM SAT
COASTAL THRU THRU THRU THRU
HURRICANE WARNINGS ARE NOU IN EFFECT FROM LITTLE RIVER INLET To LOCATIONS. 2PM F,R 1 2 AM SAT 2 PM SAT 2 PM SUN 2
PLYMOUTH MASSACHUSETTS. ALL WARNINGS HAVE BEEN DISCONTINUED SOUTH OF
LITTLE RIVER INLET. WILMINGTON NC 31 X X X
MOREHEAD' CITY MCI 82 X X x
-GLORIA IS MOVING TOWARDS THE NORTH 20 MPH AND IS EXPECTED TO CONTINUE CAPE HATTERAS MC ?8 X X X
NORTHWARD AND ACCELERATE ITS FORWARD MOTION TONIGHT. MORFOLK,VA 66 x 'X X
-OCEAN CITY MD 5a, I X X
THE EFFECT OF GLORIA THROUGHOUT THE WARNING AREA CRITICALLY DEPENDS ATLANTIC CITY NJ 39 4 X X
UPON ITS PRECISE TRACK. IF THE CENTER OF THE HURRICANE REMAINS INLAND NEW YORK CITY.MY 23 14 X x
AFTER MOVING OVER EASTERN NORTH CAROLINA ... ONLY GALES WILL se MONTAUK POINT MY 6 is X X
EXPERIENCED NORTHWARD TO NEU ENGLAND. IF GLORIA SKIRTS THE COAST PROVIDENCE RI 3 Is X @@x
... HURRICANE CONDITIONS WILL BE EXPERIENCED IN THE HURRICANE WARNING NANTUCKET MA 1 9 1 X
AREA. IF THE CENTER OF THE HURRICANE REMAINS OFFSHORE ALONG THE MID HYANNIS MR 1 13 x x
ATLANTIC COAST ... ONLY GALES WOULD BE EXPERIENCED ALONG THAT COAST BOSTON MA 2 28 x x
AND A MORE SERIOUS HURRICANE COULD AFFECT-LONG ISLAND AND NEW PORTLAND ME X 20 1 X
ENGLAND. HURRICANE FORECASTING SKILLS ARE NOT SUFFICIENT TV PREDICT BAR HARBOR ME x It 3 x-
WHICH OF THESE POSSIBILITIES WILL OCCUR. THEREFORE ... THE COURSE OF EASTPORT ME X 6 5 X
LEAST REGRET IS TO EXTEND HURRICANE UARNINGS NORTHWARD TO MASSACHUSETTS. ST JOHN MB x 4 4 1
MONCTON He X 2 5 1
TIDES OF 8 TO 12 FEET ABOVE NORMAL WILL OCCUR HEAR AND TO THE RIGHT YARMOUTH NS X 3 2 X
,OF WHERE THE CENTER CROSSES THE-.COAST AND RANGE UP TO 6 FEET ABOVE HALIFAX MS x I I X
NORMAL ON THE OUTER BANKS. DETA(iLs ON ACTIONS TO BE TAKEN ARE INCLUDED SYDNEY NS X X I I
IN STATEMENTS BEING ISSUED BY NATIONAL WEATHER.SERVICS OFFICES AND EDDY POINT NS X X I I
LOCAL GOVERNMENT OFFICIALS. EVACUATION FROM OFFSHORE ISLANDS SHOULD PTX BASQUES NFLD X x z 3
BE HEARING COMPLETION OVER EASTERN 'NORTH CAROLINA. BURGEO MFLD X X. 1 2

AT 9 PM EDT ... 220OZ ... THE CENTER OF GLORIA WAS HEAR LATITUDE 32.6 X MEANS LESS THAN ONE PERCENT
NORTH LONGITUDE 76.4 LEST. THIS POSITION IS 198 MILES SOUTH OF
CAPE HATTERAS NORTH CAROLINA.

A HOAA PLANE REPORTS THE WINDS ARE STILL 13a MPH AND THE CENTRAL
PRESSURE IS 942 MILLIBARS ... 27.82 INCHES.

GALE FORCE WINDS EXTEND 208 MILES TO THE NORTH AND 150 MILES TO THE
SOUTH OF THE CENTER.

SMALL CRAFT NORTH OF PLYMOUTH THROUGH MAINE SHOULD NOT VENTURE FAR
FROM PORT.

REPEATING THE 6 PM EDT POSITION ... 32.SN...76.4W.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER
AT 9 PM EDT. SOURCE: Bridgeport Weather Service
Stratford, CT.
FRANK

FIGURE 3.2: Forecast for Hurricane Gloria, Showing.Probabilities
of Landfall

3-10

on local conditions, and both the New York WSF0 and the Bridgeport and Hartford
WSOS will supplement the forecast and warning with a report on loca 1 conditions.
(20,68,69)

State of Connecticut Procedures

Offices of two Connecticut State agencies, identified as the State Warning
Points, are responsible for receiving and disseminating emergency warnings.
The primary State Warning Point is located in th e Communication Division,
Connecticut State Police (CSP), in Hartford. This location is manned continuously
by full-time civilian radio, dispatchers. The alternate State Warning Point
is located at the Connecticut. Office of Civil Preparedness (OCP) in Hartford.
This office is manned during normal work ing days from 8:00 am to 4:00 pm.
The OCP handles warning messages during working hours only. After hours,
the CSP initiate warning activities.

Both Connecticut State. Warning Points receive their information via NAWAS,
NWS Teletype, and. NOAA-VHF radio. Upon receipt of a weather watch or warning,
the State Warning Point activates the state NAWAS and COLLECT (Connecticut
On7Line Law Enforcement Communications Teleprocessing) systems to distribute
the warnings to each regional OCP office and appropriate officials in each
municipality. Towns not equipped with either NAWAS or COLLECT systems (Figure
3.3) must be reached through the fanout system JFigure 3.4). Connecticut
State Police Troups located in coastal areas may assist local officials in
observing flood conditions, alerting residents, and taking -other actions,
such as blocking flooded roadways. (78,79,80,81,82,83)

Municipal Procedures

Local cities and towns receive weather warnings through the State warning
system, directly from NOAA Weather Radio, and from T.V. and radio stations.
According to local officials, flood warnings are often received from NOAA
Weather Radio and local media before they are received through the State Warning
System. This may reflect, in part, that coastal flood conditions develop
over a period of time and the regular weather forecasts usually provide some

0 0
0
0
0
0
0
0
o5 0

0 0

....... . ..
0 -1, -10 - -------
4
A
01 0 01 0
0 2 0
0 0
0
0
O'COMMUNITIES WITH THE COLLECT..SYST
0
19 COMMUNITIES WITH THE NAWAS SYSTEM
0
COMMUNITIES WITH BOTH COLLECT AND
0 A REGIONAL OR COUNTY FIRE RADIO
SOURCE: Office of Civil Preparedness. OFFICE OF CIVIL PREPAREDNESS REGI
1981. Emergency Operations Plan.
CT Office of Civil Preparedness,
Hartford, CT.

FIGURE 3.3-. Connecticut Communities with NAWAS and COLLECT Systems

3-12

Warning
sources

State Police ......
(State Warning
Point) War

Network
22 Control
(Tolland)
NAWAS state
Aqenci
Drops For es
Including State
Fire
Radio r'--
a::
pr',v@
Agnc

Private te
Local Sta
Agencies Fire
Fanout Radio
169 Towns
ILocations

ESS
WTIC/WDRC - - - - - - -
CSP (AM & FM)
Troops

National P lic LEGEND
Weather -----After Duty Hours
Service - 24 Bouts
---Duty Hours Only
*Authorized to initl
NNOAA VHF statewide xMWAS warning
weat"r Radio
Subscribers (Tolland. Meriden
Montvillal

SOURCE: Office of Civil Preparedness. 1981. Emergency Operations Plano
CT Office of Civil Preparedness, Hartford, CT.

.FIGURE 3.4: Connecticut Warning Flow Chart
_'C
(Alte@;..te
Wr.1 t)

@61 @te

3-13

indication that a weather watch or warning will be forthcoming well before
it is actually issued.

Local officials generally do not rely entirely upon official flood warnings.
They also make their own observations of storm surge levels, and make decisions
based on these observations combined with their knowledge of areas prone,to
f looding. Local observations and decisions are particularly important for
winter storms. During hurricanes, as indicated during Hurricane Gloria, NWS
warnings may affect local decisions more than local observations of flood
conditions.

Once a f lood w arning is received at the local level and confirmed by
observations, officials utilize several methods of notifying local residents
of specific actions, such as evacuation, that should be taken. The most common
methods of disseminating information locally are: areawide sirens, areawide
public address systems, car mounted loud speakers, and door-to-door notification.
Some towns also use local beach associations and telephone calls to notify
area residents., In some towns the local civil preparedness office establishes
direct contact with a local T.V. or radio station. Many local civil preparedness
officials also maintain telephone contact with the Bridgeport WSO to ensure
that they are informed of the latest conditions and forecasts. (32,78,79,80,81,
82,84,85,86,87t88,1699170)

4-1

4.0.- REVIEW OF AVAILABLE TECHNOLOGY AND PROGRAMS

This section examines available techniques and programs which may be applied
to develop a Connecticut coastal flood 'monitoring network and warning system.

Ll STORM 5URGE AND

Theoretical models can be used. to'@'predict storm surge levels associated
with storms. All-theoretical models involve some assumptions and approximation
of the actual physics involved in storm surge generation. The simplest models
are statistical, and, correlate observed storm surge with other meteorological
or oceanographic phe rnomena. With the widespread availability of powerf ul
computers in the 19601s, more complex 'numerical models were formulated to
predict storm surge. A summary of" applicable statistical 'and numerical storm
surge models is provided below, and a fuller discussion is presented. in Appendix
B.

Storm'Surge Models

STAT15TICAL STORM SURGE STU121ES FOR LIS There have been three major statistical
@tudies of' storm surges along the coast of Connecticut. The f irst, in 1973,
was published by. the New England Division of the COE (89). The COE revised
this work in 1980 (6) during a second study using tide-gage data from stations
at Willets Point, NY, and Stamford, Bridgeport, New London, and Stonington,
Connecticut. A major decision in the 1980 study- was to eliminate the 1938
hurricane data from the statistical model,' thereby lowering the 100-year flood
estimates, particularly in eastern Connecticut (Figure B.1). (46)

The most recent study was perf ormed in 1982 by Dewberry and Davis, Inc,
under contract to FEMA (46)9 and was essentially a review of the 1980 COE
study. The major difference was 'of the 1938 hurricane data in their

4-2

statistical model f it, particularly in eastern Connecticut where the 1938
surge was highest. FEMA adopted the 1980 COE surge profiles, except in the
New London area where they were increased to fit the 1938 hurricane data.
The resulting profiles (Figure B.2) were used by FEMA in updates to coastal
flood insuranc e studies.

NWS STORM SURGE MODF1. FOR EXTRATROPICAL STORMS In the early 1970's, at the
request of the NWS Eastern Region Headquarters at Garden City, Long Island,
the NWS Techniques Development Laboratory (TDL) developed an empirical model
for predicting storm surge during . extratropical storms at 12 locations along
the U.S. east coast. Separate regression equations were derived for each
station by relating observed storm surge at each station to sea level pressure
at six-bour intervals at selected points along the east coast and. over the
Atlantic Ocean. Two versions of the model are available: an automated model
that uses sea level pressure data at several locations directly from a . NMC
computerized database, and a manual one that can be used at WSFOs based on
observed sea level pressure. (15,32p7l973990,69)

Stamford, Connecticut is one of the 12 locations for which regression equations
were developed. Review of observed vs. forecast surges, as provided by the
NWS (Figure 4.1), indicates that the model consistently over-estimates storm
surge at Stamford. The COE, which uses NWS storm surge forecasts as an aid
in operating the Stamford Hurricane Barrier, reported that predicted surges
are usually higher than recorded surges. No systematic records of predicted
vs. recorded storm surge at Stamford have,been maintained to measure the forecasrt
accuracy over a long term period. The models have not been recently updated.
(39t7l,73,75)

hJUMERICAL STORM SURGE MOD-=To predict, the storm surge associated with
a particular storm, statistical storm surge summaries are inadequate, and
a realistic model of the effects of winds and barometric pressure on the surface
of the water of a particular basin is needed. These more realistic numerical
models are complex and require powerful computers. They generally use as
input some representation of the storm, including central pressure index,
wind distribution and speed, storm track and forward speed, and a representation

&7
4 3.4 4
LJ_
0 HOUR
-2 ANA LYSIS -12

3.4 4

06-AND 12-HR
-2: FORECASTS -2

3.4
4 4
LU 2[
2
18-AN'L) 24-HR
FORECASTS.

3.4
4 4
2 2
30-AN'D 36-HR
-2 FORECASTS -2
-4

FEN 17. 1972 Is 19 20
FEB 2. 1972 3 4 a

SOURCE: Pore, N.A.F W.S. Richardson,
Forecasts of storm surge based on sea-level pressure forecasts Perrotti. 1974.. Forecasting
are shown by dots. Solid curves indicate observed storm surges. tropical Storm Surges for the
Arrows indicate times of astronomical high tide. The date of Coast of the United.States.
each day is placed at the 1200 EST position. Maximum value Technical Memorandum NWS TDL-
of observed surge is placed near peak of each curve. Washington, D.C.

FI,GURE 4.1: Comparison of Forecast Vs. Observed Storm Surge
at Stamford, Connecticut

4-4

of the basin, including topography and batbmetry.

NUMRRICAL TIDE AND STORM SURGE MQDELS USED IN LIS Many numerical tide and
storm surge models have been developed for application in different areas
and to achieve specific purposes. A few of these models, or portions of larger
models, have been used in Long Island Sound. However, only the NWS SLOSH
model is presently operational in a Long Island Sound version. The SLOSH
model and one additional set of numerical models potentially applicable to
LIS are briefly reviewed below, and in more detail in Appendix B.

NWS SLOSH Model -- SLOSH (Sea, Lake, and Overland,Surges from Hurricanes)
is a numerical model developed for real-time forecasting of hurricane storm
surge along the continental shelves, including large estuaries and. bays.
It was adapted from an earlier model used by NWS, SPLASH (Special Program
to List Amplitudes of Surges from Hurricanes), which did not apply to large
embayments like Long Island Sound. The SLOSH model includes a storm wind model,
which is fed by several time-dependent meteorological storm variables:

(1) Latitude and longitude of storm positions, at 6-hour intervals, for
a 72-hour storm track. This begins 48 hours before the storm's nearest
approach, and ends 24 hours after the nearest. approach.

(2) Storm central pressure at 6-hour intervals.

W S torm size (center to region of maximum winds) at 6-hour intervals.

Winds are computed independently by, the mode4 and are not input parameters.
Only initial still-water elevations at the boundary regions of the model
are required; actual storm surge levels are not input parameters after the
model begins running.

The SLOSH model does not include a tide model within it, because of the
uncertainty in timing of tropical cyclones with respect to the surface tide,
and because the SLOSH model is also used in a forecast, or "atlas" mode, where
the storm surge is simply added to the corresponding tide (see Section 4.4.1).
(91992,93,94)

4-5

The SLOSH model is being applied to 22 basins, covering most of the Gulf
of Mexico and Atlantic coastal areas, as shown in Figure 4.2. The NWS can
run the SLOSH model for a basin as the hurricane approaches within-six hours
of landf all. As a hurricane or tropical storm moves up the Atlantic coast,
the SLOSH model can be run for successive basins. The computers and data
input for ru nning the SLOSH model are located at NWS offices in Silver Springs,
but output from the model is routed to the NWS National Hurricane Center WHO
at Coral Gables, Florida.

NWS estimates that the SLOSH. model will predict storm surge levels with
an error of about +/-20% (e.g.,, an acceptable predicted range of 8-12 feet
f or an act ual surge of 10 feet at a specific location). Of Pourse, achieving
the 20% accuracy level requires that the input parameters be accurate: the
basin must be properly described, initial still-water levels at the boundaries
must be accurate, and the storm itself must perform in accordance with forecasts
(pressureq track, forward speed, etc.) The 20% accuracy level has been verif ied
for many coastal locations (including large embayments such as Galveston Bay
and Chesapeake Bay), using observed data from historical storms. For real-time
applications of SLOSH, achieving a 20% accuracy level.is more difficult, because
the storm surge estimates are related to storm track and forward speed, which
often vary from forecasts.

Two of the SLOSH basins Narragansett/Buzzards Bays 2), and New York/Long
Island Sound 0 3) cover LIS and coastal Connecticut. The New York/Long
Island Sound SLOSH basin became operational only within the past year f ollowing
input of required bathymetry and topographic data at grid coordinates. The
model was first used operationally for the Long Island Sound area in September,
1985 for Hurricane Gloria. Because the storm took a more easterly track than
forecast, the predicted storm surge in LIS from Hurricane Gloria was significantly
greater than the surge that actually occurred.

Although the SLOSH model -is now operational for LIS.and was used in a real-
time mode during Hurricane Gloria,'it has not yet been verified using historical
storms that crossed over or near LIS. The shallow water in LIS, effect of
Long Island on dissipating storms, and other factors peculiar to LIS may adversely
affect the accuracy of SLOSH storm surge predictions in LIS. (72,93v95p96097,98)

4-6

lot

SLOSH BASINS

1. BOSTON BAY 12. FLORIDA BAY
2. NARRAGANSETT/ 13. CHARLOTTE HARBOR -4d,
BUZZARDS BAYS 14. TAMPA BAY
3. NEW YORK/ 15. PENSACOLA BAY 2
LONG ISLAND SOUND 16. '24OBILE BAY
4. DELAWARE BAY 17. LAKE PONTCHARTRAIN/ 3
4e 5. CHESAPEAKE BAY NEW ORLEANS 4
6. PAMLICO SOUND 18. SABINE LAKE
7. CHARLESTON HARBOR 19. GALVESTON BAY
8. SAVANNAHMILTON HEAD 20. MATAGORDA BAY 5
9. BRUNSWICK 21. CORPUS CHRISTI BAY
10. LAKE OKEECHOBEE 22. LAGUNA MADRE
11. BISCAYNE BAY

3cr-

17 16 15 14 10
19
20
21 @13
22

12
se

SOURCE: Jelesnianski, C.P,, J. Chen, W.A. Shaffer and A.J. Gilad. Undated.
SLOSH - A Hurricane Storm Surge Forecast Nodel. Techniques Development
Laboratory, National Weather Service, NQAA, Silver'Spring, MD.

FIGURE 4.2: SLOSH Basins Along the Gulf of Mexico and
Atlantic Coastlines

4-7

Spaulding Models The Spaulding Models are 2-dimensional, vertically
integrated finite difference models. Although primarily tidal models, they
could be adapted easily to -include storm surge effects. The models appeared
to work well on tidal time scales important for coastal flooding.

Since. storm surge effect's have not been included 'in the models as applied
to LIS, there was no -wind stress term, and the time history of development
of a wind field could not be included. In a later application of the model
for the North Sea,, wind- stress (or surface stress) was included in the formulation
using boundary fitted coordinates. Any future 'application of the Spaulding-type
models must include. a storm model for generating vector wind fields. Costs
of converting these models to include storm surge effects, including verification,
are estimated at between $50,000 and $100,000. If developed, this model could
be applied to extratropica-1 storms. Preparation of a series of innundation
maps based on multiple storm scenarios (similar to procedures used with the
SLOSH model), would probably cost well in excess of $100,000. (999100,101,174)

Wave ForecastinrjHindcasting Models

Wa ve forecasting and hindeasting is accomplished by app roximating the physics
of wave generation and wave transformation using models., In general, wave
models can be considered discrete or* parametric, although hybrid models have
recently emerged. The discrete models are complex, and attempt' to directly
simulate the wave energy balance or transport equation. In contrast, with
parametric. wave. models' the major features of a wave are derived more simply,
and require less computation (often relying upon: nomograpbs). There is cdnsid-
erable debate over which.type of model is most appropriate for shallow water
conditions, such- as exist in LIS.

COE WAVE HINDCAST MODELThe COE has historically used a parametric model
as described in the Shore Protection Manual (104). for wave hindcasting.
This method is commonly used for generating data on. wave characteristics for
use in designing coastal protective structures, when empirical wave data is
unavailable. More recently, the COE has developed a discrete wave model for
use in shallow water.

4-8

FEMA WAVE HEIGHT ESTIMATES The National Academy of Sciences,developeda metho-
dology for use by FEMA in estimating wave crest elevations associated with
any frequency storm. This model is used in the preparation of Flood Insurance
Studies and FIRMs. The method includes means for taking account of varying
fetch lengths , barriers to wave transmission, and the regeneration of waves
likely to occur over flooded land areas. It assumes a high correlation between
wave heights and still-water level for a given frequency still-water level. (171,
172,173)

NWS WAVE FORECAST MOnFT-The National Weather Service uses a wind-wave
forecast for generalized offshore wave conditions. This wave forecast is
of the parametric type, based largely on empirical relationships between the
size of waves generated by specific winds. Three parameters required to use
these nomographs are wind speed, fetch length, and wind duration. There is
@no procedure for collecting actual wave height information for comparison
with wave forecasts. (20,42,69)

For the NWS purposes of providing marine forecasts for mariners, genera-
lized wave forecasts may be adequate. However, since these nomograph techniques
ignore all details of wave scattering and dissipation, they are not ideal
for providing coastal flood warnings to coastal residents.

NUMERICAL WAVE FORECAST MODELS For best results, a numerical wave forecast
model is required, which includes the full effects of dissipation and scattering.
Several s.hallow-water, wind-wave models appropriate for providing LIS wave
forecasts are available. Costs of adapting one of these models to LIS are
estimated to be on the order of $30,000. (174)

INSTRUMENTATION

Instruments for automatically measuring and recording water levels in the.
ocean environment have been in use for over 100 years, and for measuring wave
characteristics for more than 20 years. A major improvement in recent years
has been the re placement of mechanical devices that must actually be in contact
with the water surface with "remote" instruments that need not be in contact

4-9

wi,th the water surface., Typically, these "remote" instruments are mounted
on the bottom of the ocean. (27)

Another major advance- is the use of microprocessors and other microelectronics
to provide rapid sampling and processing of data at remote locations. These
data may be stored (typically on magnetic tape cassettes) 'at the remote site
for periodic retrieval, or transmitted to another location by telephone lines,
UHF or @HF radio, or satellite. Although initial capital and installation
costs of this new generation of instruments is usually higher than the older
technology, it has generally proved more accurate and reliable, requires less
maintenance, and can be deployed in locations unsuitable for most of the older
generation of instruments.

Reliability and maintenance requirements are particularly important for
instruments used to obtain oceanographic data. 'Instruments placed in the
ocean must be' much more durable than those used in rivers and lakes in order
to withstand corrosion, biological fouling, abrasion from. sand scouring, and
damage: from. wave forces. The following sections provide an introduction to
the principal- types of instruments available for obtaining tide, storm surge,
and wave measurements.

Tide and Storm Surae Measurpments

PRIESURE SENSORS Pressure sensors measure water level' indirectly. The actual
measurement , is, of hydraulic 'pressure. Some sensors also 'measure atmospheric
pressure, and this portion of the -total pressure must be removed in order
to obtain an, accurate measurement of water level' (corrective procedures are
often incorporat ed within the sensor). @ Pressure gages do not require a stilling
well. Still-water level is normally determined by rapidly taking many samples
over a fixed time period and -averaging the results. Three types of pressure
gages are available to measure tide and storm surge levels: bubbler gages,
strain gage pressure sensors and quartz pressure sensors.

Bubbler Prave Bubbler gages, of the type now in use in LIS by NOS and
USGS, use compressed air released through a. bubble orif ice at the end of a
length of tubing on the ocean floor.. The changing head (water level) above

4-10

the bubble orifice causes a corresponding pressure change, which is reflected
in a manometer, which is usually connected to an elect ro-m ecbanical chart
recorder or some type of transmitter. Bubbler gages do not require a stilling
well, and the bubble orifice can be placed several hundred feet from the compressed
air source and recording/transmitting equipment. A typical bubbler gage instal-
lation is shown in Figure 2.10. (107,108)

Strain Lra pressure sensor; Strain gage pressure sensors utilize some
type of variable resistance sensor (e.g. hydraulic, semiconductor, or conductivity)
in combination with an electrical circuit. As pressure from the water (and
atmosphere) column changes, resistance changes (voltage varies). Voltage
ch ange is the actual measurement. Sensitivity of strain, gage pressure sensors
may vary considerably depending upon the specific type and quality of gage,
but a typical gage may have a resolution of .1% and an accuracy of .5% of
the total measurement range (e.g. for a measurement range of 30 feet, a resolution
of about 1/2. inch and an accuracy of about 2 inches). Strain gage pressure
sensors are usually highly temperature sensitive, and readings must be temperature
corrected (tbermistor often included in gage to permit automatic correction).
Strain gage pressure sensors may vary in cost from as low as $'200 to about
$2,000.

Quartz @ pressure sensor.- Quartz pressure sensors utilize a quartz crystal
with a frequency of oscillation that is a function of pressure. The frequency
of oscillation is the measurement method. Quartz pressure sensors are much
less temperature sensitive, and have lower power requirements than strain gage
pressure s ensors. They are also more sensitive and a typical reso lution is
.005% with an accuracy of .01% of the total measurement range. Quartz pressure
sensors cost in the range of $2,000 or slightly more.

Tide gages using either strain gage or quartz pressure sensors incorporate
electronics packages that control the sampling rate, length of sample (integration
time), and aver aging of samples to filter out the effects of waves. For example,
to obtain one water level sample, the instrument might average all instantaneous
water level readings over a 60-second period in order to filter out wave action.
Most instruments have variable sampling rates.

4-11

Strain. gage and quartz pressure sensors are housed in a water-tight casing
(such as plastic or aluminum), and mounted near the ocean floor. Some units
are completely self-contained, and store data on magnetic tape within the
gage. Tapes must be periodically retrieved and replaced. Other gages are
connected by underwater cable to data recording and/or transmitting units
located in nearby instrument houses.(109,110) Some typical pressure gages
are shown in Fi gure 4.3.

ACOUSTIC SENSQ :, Acoustic sensors measure the time it takes for acoustic
pulses or "shock waves" to move between the water surface and calibrated reference
points. The system described here is one developed by Bartex, Inc. A pulse
frequency genera tor/transmit ter/ transponder unit sends acoustic pulses through
a small sounding tube which is mounted on a pier or other structure and extends
from above the water level into the water to the lowest level to be measured
(35 feet maximum range). A reference source is contained within the sounding
tube. As the pu lse travels down the tube, it is reflected first by the reference
source and then by the water surface. The transducer converts the reflected
acoustic pulses (echos) to electrical pulses. An electronics package measures
the return time. for each pulse reflected by the water surface compared to
that from the reference source, and the water level is determined. This system
has a resolution of .01 foot and an accuracy of about .09 foot over the 35
foot maximum range. Measurements may be automatically initiated at intervals
of one to 99 minutes, or the unit may be interrograted at any time. Output
data is compatible with various telemetry methods. The Bartex gage has been
selected by NOS for initial use and testing in its next generation of water
level stations (see Section,4.3.1). The Bartex gage, including digital interface,
costs approximately $2,600., (109911191129113vll4) The Bartex acoustic gage
is shown in Figure 4.4.

IPFUR 01F CAGES Several other types of water level measurement gages
have been developed, including: float and counterweight (see Section 2.4.2);
resistance wave staff; microwave radar; capacitance type probes; and optical
devices that read a staff gage floating within a stilling well. (109,110)

For various reasons, none of these gages are as well suited to measuring
tide and stor m surge levels as the pressure and acoustic gages described above.

4-12

Sierra-Kisco Model 5050LL-PT
Liquid Level@Sensor
(Sierra-Misco, Inc., Berkeley, CA)

SEA DATA

Sea Data Model 635-6 Tide Recorder
(Sea Data Corporation, Newton, MA)

InterOcean Model STG 7500 Tide Gauge
(shown outside of casing)
(Inter0cean Systemst Inc., Safi Diego,tA)

F1 E.4.3: Typical Pressure Transducer Type.Tide Recorders

4-13

A
k

Aquatrak.LG-110 Series Acoustic
Water Level Measurement Instrument
(Bartex, Inc., Annapolis, KD)

FIGURE 4.4: ACOUSUC Type Tide Gage

.4-14

Wave Measurements

There are many ways to measure waves in the ocean, and a vast literature
on measurement techniques exists. Central requirements are reduced maintenance,
little drift in instrument calibration, ease of maintenance or replacement,
accuracy, reliability, and ease of adaption to this long-term gaging task.
Different instrumenta tion may be chosen depending upon whether waves are to
be measured in deep water offshore, or shallow water nearshore, and whether
measure ments are to include wave directional as well as energy characteristics.

WAVE BUOYS Wave buoys are commonly used to measure waves (and tides) in
deep water offshore lo cations. Typical modern wave buoys are floating spheres
that follow the movement of the water surface. Contained inside the sphere
is an accelerometer whichmeasures the vertical 'acceleration of the buoy,
yielding data on wave height and wave frequency. * Buoys are normally moored
to the ocean bottom. Buoys may record data on magentic tape for periodic
retrieval,, or may transmit data by radio frequency or satellite. (110) Figure
4.5 illustrates typical wave buoys.

PRESSURE GAGES . Bottom-mounted strain gage and quartz pressure sensors may
be used to measure wave characteristics as well as tide and storm surge levels
(see Figure. 4.5). For measuring wave characteristics, sampling is generally
based upon "burst," rather than continuous sampling. Determination of sampling
frequency depends upon several factors, including depth of water, and commonly
ranges from 1-2 Hz (1-0.5 cycle/second). To obtain spectral wave characteristics,
a fourier' trans formation is performed on time series data,, commonly based
on sample sizes in multiples of two. Standard sample sizes, or bursts, are
1,024, 2,048, etc. A 1,024 point sample at 1 Hz results in approximately
17 minutes of data. Analysis of data yields values for significant wave height,
significant wave periodp total wave energy, and the fraction of total energy
within each period, as illustrated in Figure 4.6.

Wave gages may be self-contained, with all necessary data processing electronics
and data storage capability built into the gage. Other options include internal
data processing, with transmission to a near shore station by underwater cable;
or data collection only, with all data processing occurring at a shore station

4-15

MR,

[email protected]

Sea Data Model 635-9
Directional Wave Recorder
(bottom mounted, shown
in mooring tripod)
(Sea Data Corporation,
Newton, KA)
NEA Model WBU-1 Wavecrest Wave'Pro-fil ing Buoy
(NBA (Controls) LTD., Parnborough, England)

FIGURE 4.5:. Typical Wave MeaBurement-Gag-es

4-16

IMPERIAL BEACH ARRAY.EMERGY
EEC 1965
PERCENT ENERGY IN BAND
(VITAL ENERGY INCLUDES RANCE 2046-4 SECS)
PST SID. HT TOT. EN BAND PERIOD LIMITS (SECS)
DAY'TIME (CH.) (CH.80) 22- 22-18 26-16 16-14 14-12 12-10 10-0 G-6 6-4
26 0901 867 469.6 4.1 3 742 920.: 9 6 t72.3 5@O 1.3
2 180 2 401.9 3 *@ 2 1 , 4
140 a .1 . 7 1@13 34' 30. 6' 0 1*6
2&& 2001 77 .3 373.8 3.4 0.3 4.0 38.' 134.3 7'6 6'. : 3.1 1.1

27 0201 80.3 401* 92.0 0.3 1.7 .*4 A 21* . .2 0.
27 080, 71.2 316 .2 . . 1.9 26 S37 5 17 It '7', I.
27 1401 59.11 223@3 4@ 7 1 @ 16 3.2 213 38: 8 II'S 0.9 4 2.0
27 2001 66.3 276.1 3.0 1.0 3.4 19@ 440.7 20.3 6.4 4.3 1.1
28 0201 64 1 257 2:4 3 & 6-7 27 136 6 14.1 4.6 3.1 2.2
28 090, 71@ 9 323: *' 3 33'6 11.2 42'6 20@2 10.9 4.1 2.9 1.7
28 1401 76.2 362.5 3.3 2*2 12.5 21:2 39.5 14.4 2.2 3.2 1.6
28 200105.0 431.9 2.3 4.3 7.8 22.7 40.3 13.8 2.6 2.9 1.6

29 0201 7&. a 367.1 4.2 1.5 9.0 33.7 30.3 13.9 3.7 Z 9 1.2
29 0001 72. 6 329.0 5.6 1.0 5.9 26.5 41.2 13.1 3.4 2 1.4
29 140172.3 326.6 5 -51.0 7.I13 0 1 3.7 1: : 1.1
4' 1 9* 6 * 0
VW 2001 643. 42". a 4.1 1.1 16. T14.1 38.7 16.3 .0 2.4 .6
30 0201 63.7 233.9 A. 1 7.2 14.9 6.7 33.6 19.9 6.2 2,0 1-0
30 0901 78.7 387.3 6 0 13.6 4.7 11.5 26,2 24.3 9.7 2.9 1.
1 7 0 1 2
30 140 80.1 400. 10 13.7 14.2 6: 614 29.4 1.3 2.7 3 20
30 2029 91.7 529. 'F 3.6 7.3 33.7to1 9: 3 12,9 IZ 3 7. 4'
31 020, "@ 06 1: 1, 2 5.1 .:7 10.3 14.1 12.2 8.0 7.4 5.9
31 0801113 797 6 4:: ,-0 28 614 619.0 9.3 10.1 6- 1 3:1
3 140 93.8 549.8 5.1 3.7 23 .019@ a12.7 9.6 9.3 7 6 5

IMPERIAL BEACH ARRAY.ENERGV
DEC 1905

PERSISTENCE
CONSECUTIVE DAYS (I OR "ME) SIGNIFICANT
WAVE HEIGHT is -*- METERS OR LEBO

METERS DAVS
0.5 1.
1.0
1.3 1: 13: '0. 37:
2-0 2, 29.
2'S 31.
3.0 31
.*. 31:
4 0 31,
4@ 3 31;
5.0 31
5'. 3':
4.0 31,

MAXIMUM DAILY SIGNIFICANT WAVE HEIGHT FOR DEC 1903

D^ft I VKC) 1 2 3 63 6 7

810. "T (M. 1.6 0.8 2.4 1.6 1.6 1.7 1.5

DATE I DEC) 9 9 10 it 12 12 14

SIG. "T (Ff.) 1.8 1.7 1.4 0.9 1.2 1.5 1. 2

DATE DEC) is 16 17 is 19 20 22

519.KT (M. 10.9 0.5 0.6 0.0 0.9 0.4 O@ 7

DATE, t DEC) 22 23 24 23 26 27 20

910. HT (M. 1.0 1.1 1.6 1.0 0.9 0.0 0.9

DATE DEC) 29 30 31

SIC. my tn. ) 0.0 0.9 1. 1

SOURCE: U.S. Army Corps of Engineers, and California Department
of Boating and Waterways. 1986. Coastal Data Information
Program, Monthly Report, December 1985. Monthly Summary
Repor t No. 119.

FIGURE 4.6: Sample Analysis of Wave Parameters

4-17

(data transmission by underwater cable). (110)

Several pressure gages may be arranged in an array to obtain directional
wave data. Directional wave recorders are also available' that measure wave
direction by means of an electromagnetic flow sensor. (110,115)

Meteorological Instruments

An enormous variety of meteorological instruments is available for automatically
sampling a wide range of meteorological conditions. Meteorological parameters
most applicable to a coastal flood monitoring network and warning system are
wind speed and direction and barometric pressure. No review of the different
types of instruments available is provided in this report.

Data Tran id Processing

Microprocessor technology has greatly increased the speed of data processing
and has made real-time data collection,. transmission, and processing practicable.
With the availability of microcomputers in the early 19801s, this real-time

is now av
capability i ailable to small scale users at a reasonable cost. In
the simplist terms, this technology involves iransformation 'of. raw date into
a digital format for processing *and transmission; transmission by telephone
lines, radio frequency, or satellite; and transformation of processed data
into appropriate statistical data, engineering terms, graphics, or other appro-
priate forms. Unfortunately, there is a great lack of standarization in the
technology- by which data are collected, transmitted and processed. Consequently,
specific applications such as a Connecticut flood monitoring network generally
cannot be deployed simply by assembling individual components from different
vendors. Almost. inevitably, some off-the-shelf components will not be fully
compatible with others,- requiring that some hardware and/or software components
be customized.

As an example, the Connecticut ASERT system is not compatible with some
other real-time meteorological, hydrologic and oceanographic systems, particularly
some wave measurement systems. One limitation'ls that ASERT is a one-way
communications system; it transmits data only from the remote field- stations

4-18

to a base station. The field units may not be queried (interrogated) from
the base station (with ASERT the user may interrogate the base station unit
for data stored in the computer memory). By contrast, some storm surge and
wave measurement systems are based on: two-way communications,. A user, at the
base station may directly interrogate the field station to obtain the most
recent measurements. If the sensor and related electronics package permit,
the user may also reprogram the sensor to change sampling rate or perform
other modifications. Two-way communications systems are more expensive than
a one-way communications system. A two-way system would not be compatible
with the radio repeater stations used with ASERT.

ASERT is also an event reporting system: field stations transmit rainfall
and streamflow data at random times whenever a sample differs from the previous
sample by a predetermined amount (meteorological measurements are transmitted
on a timed basis). Because transmission time of a single piece of data is
brief less than .25 second) very few individual transmissions will be lost
due to interference. Lost data units (such as may occur, during an intense
rain storm) are not critical to overall data quality since all data is transmitted
in equal units (e.g. 1.0 mm of rainfall), and the data coding and software
permit all data transmissions to be accumulated even if individual units are
lost. Wave data are normally transmitted on a timed basis to avoid interference
and loss of data. Unlike rainfallo streamflow, and storm surge, every piece
of.wave data is required in order to obtain wave spectral parameters. Conse-
quently, measurements of full wave characteristics cannot be sent over the
same radio frequencies or use the existing radio repeaters and base station
receivers that are part of ASERT without compromising the wave data. (61,110,116,
117,174)

COASTAL MONITORING, FORECAST AND WARNING PROGRAMS

Several significant developments are underway or planned which may influence
the way in which a Connecticut coastal flood monitoring network and warning
system should be designed and operated. In addition, several existing real-
time monitoring and warning networks provide, useful information for design
considerations.

4-19

Federal Program Activities

EEMAHURRI!QANEPRFPAREnNESSPROGRA FEMA, in cooperation with NWS, the COE
and coastal states, has underway a Hurricane Preparedness Program. Among
the objectives of this program is the development of special evacuation elements
for inclusion in state and local emergency operations plans, in response to
the approach of hurricanes in bigb-@risk, bigh-population areas. A complete
Hurricane Preparedness Study for a region may require 3-5 years to complete
and cost on the order of $2,000,000. The studies are federally funded with
contributions from FEMA, NWS, and COE. State and local officials contribute
staff time to work with federal agencies.

One of the first elements of a Hurricane Preparedness Study is performance
of a Hurricane Hazard Analysis. This is an analysis of the expected hazards
that would require the temporary emergency relocation of some portion of the
population. The results of the analysis form the basis for determining vulnerable
areas that require evacuation. The principal tool used in the hazard analysis
is the NWS SLOSH model. Instead of running SLOSH in a real-time mode, it
is used to run a series of simulations of possible hurricanes. Normally,
the five storm intensities of the Saffir/Simpson scale are simulated. Three
hundred or more simulation runs may be performed, representing various combinations
of burricaneintensity, track, size, and forward speed.

Each hypothetical hurricane simulated by SLOSH would confront an area with
one of many distinct hazard scenarios which, in turn, ultimately make up the
evacuation scenarios, or levels. The output of the SLOSH model provides four
major types of information on the effects of the simulated hurricanes. They
are: 1) Surface envelope of highest surges above mean sea.level; 2) Time histories
of surges at selected gages or grid points; 3) Computed wind speeds at selected
gages or grid points; and 4) Computed wind directions at selected gages or
grid points. The results of individual surge mo Idel simulations (and/or groups
of common intensity/track types, termed Maximum Envelopes of Water - MEOWs),
will provide predicted storm surge elevations. Innundation maps based on
these predicted storm surge elevations will indicate vulnerable coastal areas
and will form the basis for several distinct' evacuation levels.

4-20

According to FEMA a nd NWS personnel, current plans are, to begin the Hurricane
Hazard Analysis, including running hurricane simulations for the Narrangansett/-
Buzzards Bay SLOSH basin (Figure 4.2 and B.3),, in the latter part of calendar
year 1986. A definite schedule for beginning a Hurricane Hazard -Analysis
for the New York/Long Island Sound SLOSH basin (Figure 4.2 and B.4).has not
yet been established, but it may begin in FY 87. The start. date will depend
upon available funding and . priorities among basins. Once the simulations
for these basins have been run and MEOWs developed, the MEOWs will.form the
basis for evacuation notices; not the forecast storm surge from a real-time
SLOSH run. 'Although NWS will continue to run SLOSH in a real-time mode as
a hurricane approaches, it will base all public warnings for evacuation purposes
on the MEOWs applicable to the forecast track, intensity and forward speed
of the hurricane. The accuracy of the MEOWs relative to the actual storm
surge will largely depend upon the accuracy of the hurricane forecast.

As indicated in Section 4.1 and Appendix 13@ the SLOSH model may have some
limitations as applied to LIS. Connecticut (as well as New York and Rhode
Island) officials should work closely with the FEMA, NWS and COE in the application
of the model to LIS to ensure the most favorable results. (71972,93296p979118p
119,1201, 121,122)

NOS KGWLMS PROGRA The NOS operates and maintains the National Water Level
Observation Network (NWLON) to accomplish its mission requirement for measuring
and disseminating tides and water level data. Because the technology used
to support the NWLON is aging and obsolete, NOS will replace it with a modernized
system,, the Next Generation Water Level Measurement System (NGWLMS). NGWLMS
is a fully integrated system encompassing new technology sensors and recording
equipment, multiple data transmission options, and an integrated data processing,
an alysis and dissemination system.,

NOS has, selected an acoustic gage (manufactured by Bartex, Inc., and described
in Section 4.2) for measuring tides and storm surge, with a pressure gage
as backup. The acoustic gage will receive further . evaluation during initial
installations, so its selection 'is not entirely assured for the entire new
system. NOS apparently has, no plans to measure wave characteristics (most
NOS gage stations are located in areas at least partially protected from wave

4-21

action). Information will be collected and transmitted in near real-ti me.
The primary means of data transmission will be by GOES Satellite. Radio and
telephone telemetry is also planned. Figure 4.7 illustrates the proposed
system. NOS plans to make available to interested users a software program
(floppy disk for-use in a microcomputer) which will enable the users to obtain
both actual (near real-time) and predicted (as in published tide tables) tide
levels by connecting with any NOS gage through a telephone modem.

NOS hopes to have NGWLMS fully op erational in the late 1.980s or early 1990s.
However, the schedule for upgrading tide stations has not been finalized and
will depend upon several factors such as need for equipment replacement, geographic
spread of initial installations to be used for continued testing and evaluation,
and available budget. NOS has indicated that it would invite interested states
to enter into cooperative agreements for early installation of gages in their.
area (in Connecticut one of the two NOS gages could potentially be included
as an early installation). (27v98,123, 1241,125)

NWS TRLFMRTRY JJPDATE The NWS generally does not own and operate its own tide'
gage stations. But at many NOS gage stations, such as Bridgeport, the NWS
does operate a tide level recording unit off of the NOS primary gage. The
existing equipment (Bristol Metameter) is old and no longer reliable, so the
NWS is now installing new telemetry instrumentation (Ha ndar, Inc., Model 540A)
at selected NOS gage stations. This new instrumentation is intended to provide.
near real-time data to the NMC in Silver -Springs to improve NWS forecasting
ability, as well as continue to have real-time data available in local NWS
offices. Use of this new equipment is intended to be temporary: as NOS upgrades
its NWLON system with the new gages and telemetry, NWS will remove its Handar
instruments. and. redeploy them in riv erine areas. A Handar unit is expected
to be installed by NWS at the Bridgeport NOS gage in the very near future
(unit already available at Bridgeport WSO office). One disadvantage to the
Handar equipment is that it will not provide a continuous display and chart
record of tide levels as the present Bristol equipment does. Instead, local
NWS personnel must interrograte the gage to obtain tide levels. (32,33,34,98,117,
1239124,125t126v127)

000
GOES
Optional Telephone Link
to Real Time Users N::r.Real Time
a Academic Instl
a NWS
CRT a Marine boundar
Programs
a Others
a Pilots
a Shipping Companies
a Port Authorities
a Vessel Traffic Control
6 KWS F--DQA
a Others 4@
S

Satellite Down
Link Master Collection
Optional Radio Link computers
to Real Time Users

Optional n
Telephone ink
A
Level
Miccoprocansd I

DQ
u Data
z processing
ionsor Referenced Computer
to bench mark System

Tide Staff for
G Periodic Chocks
,;neral Navigation
drography
a Dredging Air Acoustic or Non-contact Sensor
in ecotective/Stilling Well

Other Sensors as Required
Optional (i.e.. water temperature. salinity,
currents. irul direction and speed,
Pressure air temperaturej barometric pressure, etc.)
Sensor

SOURCE: Deibelp Lawrence E., and Barbara A. Zumwalt. 1985. Next Generation
Water Level Measurement System Program. By The Mitre Corporation
for National Ocean Service, NOAA, Dept. of Commerce.

FIGURE 4.7: National Ocean Service NGWLMS System

4-23

FEDERAL INURAGENCY STANDARDS COMMITTEE In response to the lack of standarization
in the equipment manufactured for. measurement,, transmission and analysis of
meteorologic, hydrologic and oceanographic data, a-federal interagency standards
committee was formed in the summer of 1985. The first meeting of the committee
was scheduled for October, 1985. (98,128)

FEMA IRMIS PROGRA FEMA-has developed an Integrated Emergency Management
Information System (IEMIS) that is intended to allow FEMA headquarters, training
center and regional offices,. and state and local governments to perform data
sharing, joint planning, exercising and - potentially -- operational coordina-
t ion. Currently, the system is on-line at the FEMA headquar ters, regional
officesi and training center. IEMIS uses a 'standard national map for display
of information. The system originated with FEMA's Radiological Emergency
Preparedness Program, and future de. velopments are planned to include adaptations
for hurricane evacuation and evacuations below failed dams, among others.

Currently; FEMA is cooperating with the NWS and City of Tulsa, Oklahoma
in development- of, an operational flood warning system on IEMIS. FEMA indicated
that it is seeking other states, localities and private contractors to participate
in pilot projects. Other states actively' involved with IEMIS include Louisiana
and Massachusetts. Connecticut is not presently pursuing operational invo lvement
ith IEMIS.- Although IEMIS program goals are ambitious, it is unclear at
this time whether there is a real need or opportunity for a Connecticut coastal
w

flood monitoring network and warning system to be operationally compatible
with IEMIS.'(1219129913091319132,1339 134)

4= Real-Time Programs

COA5TAL RNING PROGRAMS

Tsunami Warning TheNWS,'in cooperation with NOS, operates a tsunami,warning
system An the' Pacific Ocean. Wave data is telemetered to a central receiving
station. When an earthquake occurs or wave characteristics indicate the potential
for a tsunami, the gages are signaled to increase their sampling rate. (27)

4-24

Harrison County, Mississippi Water Level Monitoring System The Harrison
County, Mississippi Office of Civil Preparedness (Gulfport area) is currently
developing a real-time.flood warning system. This system is very similar
to the Connecticut ASERTIALERT system, and will include 3 river and 3 coastal
sites. Data will be transmitted by VHF radio to the Civil Preparedness office.
Officials feel this system will provide them with accurate information on
storm surge without having to send out observers under dangerous conditions.
Wave characteristics will not be measured, nor is any predliction of storm
surge planned. (163,164)

Thamgs River Fs tuary. England An operational system in the Thames River
Estuary provides the Canterbury City Council with real-time data on tide and
wind conditions. One station (pressure transducer) in the harbor at Whitstable,
transmits tide and wind data at regular intervals by dedicated telephone line
to the Council offices in Canterbury. A similar station out in the estuary
transmits data by radio frequency. The receiving station is. equipped with
a modem and a speech synthesizer, so that it may be accessed from any location
and a synthesized voice will report tide and wind conditions. (165)

Ganges River/Buy of Bgngral Flood J%arning Network In cooperation with the
National Aeronautics and Space Administration (NASA), the government of Bangladesh
has installed a network of 10. tide gages along the Ganges 'River and a fully
equipped meteorological buoy in the,Bay of Bengal. Data are transmitted through
the ARGOS Satellite System to a ground station in Dacca, the capitol of Bangla-
desh. Early warnings provided by this system were credited with saving numerous
lives during the disastrous May 1985 cyclone which struck the Bay of Bengal.
(166,167)

NAVIGATION PROJECTS

New York Harbor Tidal Gage System The "New York Harbor Tidal Gauge System"
is a cooperative effort between NOS, New York Department of State and the
Maritime Administration of the, Port of New York (MAPONY). It provides real-time
water level data from four NOS tide gages., The system is oriented primarily
towards navigation, but can also be used for other purposes, including input
to weather forecasts. Tide level data from the four gages are available via

4-25

telephone telemetry to a microcomputer (IBM PC) at MAPONY offices, the New
York WSFO and system subscribers. Data are available on a computer terminal
display or paper printout (See Figure 4.8). No provision has been made for
permanent data storage.

System installation costs' of $250,000 were provided by the New York Department
of State. Anyone may subscribe to the system with a $100 connection fee and
.$100 monthly charge. A compatible microcomputer or terminal and a modem are
all that is required to access the system. The system was intended to be
financially selfsupporting through subscriber fees, but there are currently
only three paid subscribers and the possibility exists that the system may
be shut down. Although reportedly providing accurate and useful information,
the system has suffered reliability problems because of difficulties with
the telephone lines.

The primary users of the information are the NWS and the Sandy Hook Pilots
Association (movement of ships in and out of New York Harbor). The New York
WSFO, uses data from the system as input to its weather and stor m surge forecasts,
including data during Hurricane Gloria. Altb ougb proponents of the. system
(including NOS and MAPONY) speak of the tremendous financial savings available
to ship owners by being able to move ships sooner or more fully loaded, most
ship owners apparently remain unconvinced. and have bee n unwilling to provide
financial support for the system.

The Ne w York WSFO reported that it found real-time information from the
network to be of great value during Hurricane Gloria. One station was not
operational during Hurricane Gloria because of problems with the telephone
lines, another gage was operational during only part of the storm, and two
gages were operational through the entire storm. (22J25913944091419142J43,
1449146tl47,148,149,153)

Delaware Bay Navigation Project NOS has funded a special Delaware Bay
Program which incorporates a numerical model of tide levels and currents in
the Bay. The model, combined with four acoustic tide gages, several current
meters, and meteorological instruments provides real-time and predicted data
on currents and tide levels in Delaware Bay. This information is telemetered

4-26

-----------------------------------------------------------------------------
PORT OF NEW YORK TIDE TELEMETRY SYS-EM MAP 01
SAMPLE TIDE 6IND WIND WIND DATA SYSTEM
-<EMOTE TIME LEVEL tPEED DIRECT GUST OUALITY STATUS
STATION CEST3 EFEET] [ K.',107S .-DEG-T.-. fKt.'r-.'TS] CoCrE ncdob
-------------------------------------------------------------------------------

SANDY HOOK 09:18 +00.6 09 260
BATTERY 09:18 +00.5 oc
BERGEN PNT 09:18 +00.8 224
iT: @ =--
OF:18 +02.7

HOOK 0?:24 +00.6 09 258
BATTERY 09:24 +00.5
BERGEN PNT 09:24 +00.7 05 225
WILLETS 09:24 +02.6

SANDY HOOK 09:30 +00.5 09 257
BATTERY 09-30 +00.5
BERGEN PNT 09:30 +00.7 05 227
WILLETS 09:30 +02.5

SANDY HOOK 09:36 +00.5 09 258
BATTERY 09:36 +00.5
BERGEN PNT 09:36 +00.7 07 200
WILLETS 0.9:36 +02.4

ANDY HOOK 09:42 +00.5 09 258
BATTERY 09:42 +00.5
BERGEN PNT 09:42 +00.6 08 203
WILLETS 09:42 +02.3

SANDY HOOK 09:48 +00.5 04 258
BATTERY 09:48 +00.5
BERGEN PNT 09:48 +00.6 06 216
WILLETS 09:48 +02.2

SANDY HOOK 09:54 +00.6 04 258
BATTERY 09:54 +00.4
BERGEN PNT 09:54 +00-6 08 208
WILLETS 09.54 +02.1

SOURCE: Maritime Administration of the Port of New York, New
York, New York

FIGURE 4.8: Sample Display of Tidal Datafrom New York
Harbor Tidal'Gage System

4-27

via VHF radio t'o several computer terminals, including portable terminals
for use on ships by Delaware Bay Harbor Pilots. 'The numerical model has been
kept on-line by NOS at a cost of several thousand dollars per month. Recently,
the system was taken off-line because of costs. Although the model predicts
water levels up to 12 hours in advance, it was not. designed to provide an
accurate prediction of storm surge (does. not include all necessary wind stress
f ields). (124,125,150,151)

Addi tional NOS Supported Navigation Projects NOS has also helped develop,
in cooperation, with the COE, a real-time navigation system in the Columbia
River, Oregon; recently entered into an agreement with the Port of Miami;
and is discussing agreements with ports at Charleston, South Carolina and
Baltimore and Annapolis, Maryland in Chesapeake Bay. Although NOS indicated
that it can no longer provide funding for pilot projects, it will enter into
cooperative agreements with states and other jurisdictions to provide technical
assistance in the development of real-t ime navigation systems. (27,124,125,153)

Othe r Real-Time NaMigration PrograM Other real-time navigation 'programs
are in operation around the country, including two privately operated systems
.in San Francisco Bay. One of these (apparently no longer operating) consisted
of seven tide stations transmitting every six minutes. It was designed to
be self-supporting, charging users a. fee of $25 for each ship transit. Another
private firm operates a single tide gage at the San Francisco Bay Bridge.
Since this gage is tied to an ALERT type system'. a typical graphic display
from this gage is shown as Figure 4.9. Many tide gages with real-time data
transmission are used by dred ging operations in the Great Lakes and other
locations. (61,154,155,156,157)

National Academ@ of Sciences Report The NAS, National Research Council,,
Marine -Board ha's established a-Committee on Information for Port and Harbor'
Operations to examine the potential for real-time navigation in ports and
harbors. The committee report is due out approximately April, 1986. N6 infor-
mation is currently available from NAS. (143v152)

Colden Gate Stream Gage
6.0 1 f

5.4
A
e 4.8
v
4.2 N',

3.6

3,0.
HOUR 12 a I'll- 0 120 12 12 1.20
DAY 94 10-) 11+ 19?,4

FIGURE 4.9: Sample Display from Tidal Gage in San Francisco
Bay; ALERT Type Network
Lv-

MM@MMMMM MINN MWWWM MMM

4-29

RESEARCH PROJECTS

Other real-time *tide, storm surge and wave measurement programs 'are in
operation. Two major projects are described below.

West Coast Wave Measurement NetWork The COE and the California Department
of Boating and Waterways have funded a Coastal Data Information Program for
the collection of wave data along the west coast of the U.S. The system was
designed and is operated by the !Scripps Institute of Oceanography (SIO).
The primary purpose 'of the progr am is to improve understanding of the wave
climate along the west coast. Knowledge of the wave climate *helps with under-
Standing the potential for'"sedimient' transport and coastal erosion, which are
of major concern on the west coast. Major, users of 'the information are SIO,
the COE, coastal engineers, and more recently the, NWS and U.S. Navy.

The complete network consists of' about 20 gages, including wave buoys and
wave directional stations in deep water and pressure gages near shore. The
near shore sites use bottom mounted strain gag e pressure sensors. Data from
each gage are telemetered to a field station (by VHF radio from deep water
wave buoys, and by cable from near shore pressure gages), where time series
wave data! are 'stored in a buffer. At preset intervals,, the central station
computer at Scripps calls up the field stat ions, receives data from the buffer,
performs validity checks, analyses the data, and stores the data in a
During major storms, more frequent measurements can be taken. Data are available
in near real-Aime to all 'system subscribers, who may acce Iss the system using
a microcomputer or terminal and a modem. Historical data are also available
orr-line. Raw data are stored by the COE, Coastal Engineering Research Center
(CERC) office in Vicksburg,, Mississippi.

Date on significant wave length andperib'd (wave spectral dat a is not sent)
are transmitted from the SIO central station computer by telephone lines to
the NWS computer in San Diego. There the data are entered into the NWS AFOS
system (Automation of Field Operations and Service), transmitted to the NMC
in Silver Springs, Maryland, and then. sent back out over the AFOS system every
three hours to NWS offices in California, Oregon and Washington. These NWS
offices use the data in preparing forecasts and to report actual surge and

4-30

wave conditions in their routine weather bulletins released over NOAA weather
radio. This information is apparently very useful for fishermen and other
mariners. The NWS reports that it has had good success in obtaining and using
data from the SIO network. Even when the NWS AFOS system is temporarily down,
the NWS can call into the SIO computer system using an IBM PC microcomputer.
Recently the U.S. Navy has begun using the SIO network as part of a tsunami
warning system.

In addition to the west coast network, the SIO system includes one station
at the COE, CERC research station at Duck, North C arolina. SIO personnel
indicated that they are interested in adding other stations to their network,
possibly including a future Connecticut network of storm surge and wave gages.
Data from the local stations would be input to the SIO computer, analyzed
and them sent back out to the local area. Only a terminal and modem are needed
to connect with the SIO system. SIO charges private users a subscription
for participating in the system, and would *make it. available to a government
user with an appro priate contribution (the State of California presently con-
tributes $50,000/year, and is expected to increase their support to $100,000/-
year). SIO could also assist with installation of gages and telemetry. SIO
publishes a monthly and annual report which summarize the data collected by
the system. A subscription costs $95.00/year. (115,135,136913791389175)

Florida Monitoring Network The University of Florida at Gainsville, in
cooperation with the COE, CERC has developed a coastal storm surge and wave
monitoring system off the Florida coast. This system is designed to collect
data for engineering design and research purposes, and is not used for forecasting
storms or surge. A network of approximately nine pressure transducer gages
is installed on the ocean bottom at a depth of about 10 meters around the
Florida coast, approximately one-half mile offshore. Under normal conditions,
the system transmits data via underwater telephone cable to the receiving
unit at the University. During major storms, the system (two-way communications)
is switched to an internal mode, and data are recorded on tape stored within
the gages. (1589159,16091619162)

4-31

Long Island Sound Water Quality Program

The State of Connecticut recently began work on a new program to investigate
water quality and marine living resources in Long Island Sound. Efforts will
be focused on the western part of the Sound, where sewage effluent and other
pollutants from New York City enter LIS through the East River. The program
is expected. to include long term monitoring of nutrient input, productivity,
and circulation, which may involve tide and current meters at selected areas
in LIS. At a recent workshop, participants suggested that a two-dimensional,
vertically integrated, numerical circulation model of the Sound be developed.
Development costs for the model were estimated at more than $500,000. Start-up
funding may be available in FY 1987. (177,178,179)

5-1

5.0: FLOOD MONITURINQ NETWORK D

This section describes the general design of four different flood monitoring
networks. Each network design provides a different degree of compatibility
with the Connecticut, ASERT system, as well as variations in the type and quality
of data to be collected. Variations and enhancements to each network design
are also indicated. The final choice of a preferred network design depends
upon a number of factors, including: State budget, funding levels for federal
programs directly related to flood monitoring and warning; how dependent the
State network should be on other federal, state or private programs; and user
needs to be met.

DESIGN Q

An optimal flood monitoring network would possess the following characteristics.
(1) Accurate measurement of tides, storm surge, and wave spectral character-
istics.
(2) Sufficient number and placement of stations to measure all significant
variation in tide, storm.surge and wave action along. the CT coast.
(3) Accurate measurement of wind speed, wind direction, and barometric pressure
at each gage station.
(4) High reliablility, including continued operation under severe storm
conditions.
(5) Ability to. increase sampling frequency during storms, or at other times
as needed, from the central receiving station.
(6). Data available in real- or near real-@-time to potential users, including
State emergency officials., municipal officials, NWS, navigation interests,
and researchers..
(7) Audible alarms when storm surge and wave conditions exceed critical
levels.
(8) Processing and display of data to 'permit easy interpretation and use.
(9) Archiving of data for research a Ind verification purposes.
(10) Low equipment and installation costs.
(11) Low maintenance costs, including long life.for equipment.
(12) Fully compatible with ASERT.

No single network design appears to meet all of these criteria. In the
following sections, several network designs are, presented, each of which requires
some compromise on one or more.of tbe,criteria.

5-2

NUMBER AND LOCATI N OF GAGF-q

Tides and Storm Surga

To measure tidal action and storm surge affecting coastal communities,
gages should be placed at a near-shore location, outside the breaker zone.
Although tides and storm surge are affected. by shoreline configuration and
the presence of manmade and natural obstacles, this affect in LIS is relatively
small. (6.7,46) Therefore, gages may be placed along the open coast or within
a protected harbor with confidence that the measured tide and surge will not
vary greatly from nearby locations.

No projected storm surge data from numerical models is available for the
Connecticut coast to provide guidance for placement of storm surge gages along
the coastlinel. Therefore, empirical data gathered from storm surge observations
and statistical studies of storm surge must be used to suggest the placement
of gages. These data indicate that a reasonable measu rement of storm surge
along the Connecticut can be obtained by locat ing gages in five areas.

Stonillgton to New London Storm surge decreases from Stonington to
New London where it reaches a local minimum. The large amplification
of storm surge in the Thames River also makes this area important
for measurement.

(2) Waterford to East Haven This reach has a n almost constant upward
slope in storm surge from east to west. A point about midway along
this reach should permit determination of surge along the entire area.

(3) Nfijm Haven area: A local maximum in storm surge occurs in the area
of New Haven, and should be measured.

(4) Milford to Bridveaark- A significant and rapid decrease in storm
surge levels occurs in this area. It is also the lowest point for
storm surge along the Connecticut coast.

(5) Greenwich/Stamford area: Storm surge is largest in western Connecticut,
and this is also an area with complex offshore batbymetry and offshore

iThe N WS SLOSH storm surge model is now operational, but projected storm surges
from theoretical hurricanes have not yet been prepared. Storm surge estimates
for the Connecticut coast prepared during Hurricane Gloria were not available
from the NWS for this study. There Are no other operational storm surge models
that cover the entire Connecticut coast.

5-3

islands.

Measurement of storm surge at these five areas should permit a reasonable
estimation of storm surge at other coastal areas. However, the choi ce of
these five areas is based on historical statistical studies that minimizes

local variations and differences associated with individual storms. To determine
just how extensive local variations in storm surge may be, it is suggested
that, in -addition to establishing 'permanent measurement stations at these
five sites, additional gages be placed at critical points along the coast
for temporary periods. These' temporary stations can be used to correlate
storm surge at intermediate locations with adjacent permanent stations2.
To account for seasonal variations, these temporary stations should remain
in place at least one year.

L= Waves

Two major options are available for the placement of wave gages:

(1) Wave gages may be placed in adeep water offshore, beyond the zone of
major shoaling. Data from offshore gages, although not specific to
any single location,, can then used in a wave model (including wave
refraction, diffraction, reflection) to obtain wave estimates closer
to shore. As discussed.in Appendix B@ the ability of models to shoal
waves accurately is limited, and if the wave data are sufficiently
far offshore that wave generation continues between the gaging site
and the shore location, the shoaled wave estimates will be incorrect.
The primary advantage of offshore gages is that a few gages can be
used as representative of a large section of coastline.

(2) Wave gages can be placed very close to shore, such that the waves
measured are those that impinge directly onto the shoreline. The advantage
is that accurate, site-specific information is available for the local
shoreline. The disadvantage is that the wave data cannot be used
for adjacent coastal sites, without expensive and often inaccurate
modeling efforts which estimate offshore waves from the inshore measure-
ments,, then shoaling of these offshore waves into the candidate site.

2
This would be similar -to NOS procedures of placing temporary, subordinate,
tidal stations at many points along the coast to establish tidal correlations
with its two permanent tidal stations in Connecticut.

5-4

Because waves in much of LIS are primarily generated by local winds rather
than offshore swells, and the need for site-specific data, near-shore gage
stations are suggested, even' though the wave data may not always be used to
estimate wave action at ungaged, nearby locations.

From a theoretical standpoint, there is no single optimum spacing of wave
gages along the Connecticut shoreline. Waves will develop differently in
LIS, depending on the wind speed, direction, and orientation of the coastline.
For instance, winds moving along the maximum east-west fetch of LIS will
exhibit large alongshore gradients in the spectral wave characteristics, i.e.,
wave height and peak wave period will grow continuously with distance down
the Sound. Local effects such as sheltering by offshore islands, or refraction
by shoals, will cause significant local variability. This sheltering and
refraction will affect different parts and lengths of the coast according
to wind speed and wind direction.

Optimally', some guidance in locating gage stations would come from previous
studies of waves within LIS, either in situ measurements or numerical modeling..
As is typical for much of the east coast of the United States, little direct
measurement of waves has been made in LIS, and no comprehensive, long-term
monitoring gage records exist. Most records are very short, and of uncertain
quality, and do not warrant use in setting the spacing and location of wave
stations.

Visual observations of waves have been made at a number of locations along
the coast of Connecticut as part of the Beach Erosion Project established
following the Ash Wednesday storm of 1962 (181). These data are of questionable
quality, since visual observations are known to be biased and inexact. Although
these data were examined to try to establish a sound basis for locating gages,
this effort proved unsuccessful.

Calculation of wave development in LIS using empirical hindeast techniques
suggests that at a minimum three wave gages should be located along the shore.
In the eastern part of the Sound, waves are ne arly those of the more open
coastal waters of the Atlantic. I Further west, in the middle regions of LIS,
the waves become more typical of a sheltered embayment, while to the far west,

5-5

the wave s are almost entirely shallow-watert locally generated waves.

The combination- of the alongshore gradients in wave action and the complex
nearshore bathymetry results in a *recommendation to place three permanent
wave gages al. ong the Connecticut shoreline.

(1) Eastern Connecticut, One gage should be located in the eastern part
of the sound, along a section of shoreline exposed to both locally-
generated waves and more distantly generated ocean swell (but outside
the immediate influence of Fisher's Island.

(2) Mid-State. Another gage is suggested near mid-state, offshore of
New 1-faven. Waves in this area are, predominantly locally generated
within the Bound, having a large fetch during both westerly and easterly
winds. Although somewhat sheltered from westerly winds by the shoals
off Bridgeport, it is exposed fully to the brunt of an easterly wind.

(3) West ern ConnecticuL Another gage should 'be located near Stamford
or Greenwich. This location is representa 'tive. of . much of the western
part of the State, with its crenulated shoreline, and variable offshore
batbymetry. This area is subject to only a minor westerly fetch,
but the long easterly fetch could potentially generate large waves..

Because of local topography and offshore islands, these three sites will
not be representative of all sbore points. For example, they will not permit
determination of wave action in Fisher's Island Sound. Because the communities
in this reach of coastline (Stonington, Groton, New London, Waterford, and
East Lyme) have few structures in the.V-Zone (ref er to Table 2.4), absence
of a wave gage here is not critical. A permanent gage can be added in this
area later if needed. To determine if additional permanent gages are needed
and to attempt statistical correlation of wave beh avior between the sites
with permanent gages and nearby ungaged sites, it is recommended that two
additional wave gages be used to temporarily measure sites at various locations
along the coast. Because wave climate during, a variety of weather conditions
is desired, .and to reduce installation and removal costs, it is recommended
that the roving wave gage stations remain at each'temporary location for at
least two years.

ME NRTWORK DEEIGNS

Based on the desi gn criteria given in Section 5.1 and the recommendations

5-6

for number and location of gages in Section 5.2, this section describes several
alternative network designs. Network designs which are ASERT compatible are
presented, as required by the initial study objectives. However, since -these
designs must either omit or compromise wave data (or compromise reliability
of the ASERT system), other network designs are also presented. One set of
alternatives involves a wave network separate from the ASERT compatible storm
surge network. Another alternative describes a network -totally independent
of ASERT. The - major alternative network designs, with possible variations
on each, are described below and summarized in Table 5.1.

5,3,1 Cautions on Cost Estimates

Cost estimates for equipment, software development and installation are
provided for each alternative described. These estimates must be used with
great caution. Although several vendors were contacted for cost estimates,
most were reluctant to provide estimates without a detailed set of specifications.
Those estimates provided by vendors were not always comparable because they
made varying assumptions regarding instrumentation needs. Some vendors provided
estimates for a complete monitoring network, while others provided only costs
of individual components. Costs of similar equipment can vary greatly depending
.upon quality and design standards. The equipment cost estimates in this report
were developed by the contractor based on information provided by vendors
and past experience with vendors and equipment at WHOI and elsewhere. The
estimates should be considered more as relative values than as absolute cost

,estimates.

Similarily, cost estimates for installation are approximate, and should
be considered relative rather than absolute. Installation costs do not include
surveying to establish reference elevations.

Tide and Storm Surge Measurements* (ASERT Compatible Network)

GFNRRALDESr,RTPTI0 An ASERT compatible network that measures tidal movement
and storm surge can be established that relies heavily on use of existing
recording tide stations.

ALTERNATIVE NE .TWORK DESIGNS ASERT COMPATIBILITY SAGE STATIONS TYPE OF SAGE APPRO
COE

TIDE AND STORM SURGE Existing stations at New
(ASERT Compatible). London, Old Saybrook,
Bridgeport, and
i-a Maximum Use of Existing Pully Compatible Stamford. New Station Existing gages fitted 51,000
Instrumentation at New Haven. Two with interface. Strain
roving stations gage pressure sensor at
Now Haven and roving
stations.

1-b Upgraded Instrumentation Fully Compatible Strain gage pressure 58,500
sensor or NOS gage

2. TIDE, STORM SURGE AND.WAVE Same as Alternative I Top-of-the-line strain
MEASUREMENTS except for a new station gage pressure sensor or
(ASERT Compatible) at Stamford Harbor quaVtz pressure sensor.
Breakwater to replace
2-a Simplified Wave Data Some wave data may be existing Stamford Harbor 100,00
lost due to.interference gage, and relocation of
2-h Field Station Processing Old Saybrook gage site
of Spectral Wave Data to open water side of
breakwater.
2-b.1 Transmittal of Higher percentage of 115,00
processed spectral wave data loss due"to
data longer transmission
time, and overall higher
ratio of signal
interference

.2-b.2 Store spectral data Some wave data may be I 18'00@
at field station lost due to interference

3. TIDE, STORM SORGE AND WAVE @Only 2 stations Same as Alternative 2 Top-of-the-line strain
MEASUREMENTS (Bridgeport and New gage pressure sensor or
(Two Networks) London) are-ASERT quartz pressure sensor.
compatible. Stations
3-a One-way Communications with wave gages are an a 158,00
separate network 2018,00

3-b 'Two-way Communications 280,00
330,00

3-c Linkage to SIO Wave, 163,00
Monitoring System 335.00

4. TIDE, STORM SURGE AND WAVE No t compati ble Same as Alternative 2 Quartz pressure sensor 440,00
MEASUREMENTS entirely separate system
(Independent from ASERT)

TABLE 5.1: Summary of Alternative Network Designs

5-8

Station Locations For this netw ork, five permanent and two temporary "roving"
stations are recommended (Figure 5.1).
EXISTING STATIONS

(1) NOS station in the Thames River at New London.
(2) USGS/DEP station at Saybrook Breakwater at, the mouth of the Connecticut
River.
(3) NOS station in Bridgeport Harbor.
(4) COEIUSGS station in Stamford Harbor.

NEW STATION

(5) New Haven Harbor. A new station would be located at the West Breakwater
at the entrance to New Haven Harbor.

ROVING STATIONS

(6) At sites to be selected
(7) At sites to be selected

Station Description Each station would be equipped with water level and
meteorological sensors (wind speed and direction; barometric pressure). Water
level (stillwater) would be determined and transmitted at 5, 6, or 15 minute
and meteorological data would be transmitted on an event basis.
intervals3
Each station would be equipped with ASERT compatible encoding and radio trans--
mission instruments.

At the four existing stations, the transmitter and other instrumentation
would be located within the existing instrument housing (NOS instrument housing
at New London and Bridgeport; Coast Guard lighthouse at Old Saybrook; and
COE Hurricane Barrier offices at Stamford). For the new station at New Haven
Harbor, instrumentation would be housed in a Coast Guard lighthouse tower
located on the breakwater. The antenna and meteorological instrumentation
could be mounted to the, tower. Commercial power is available.

3A measurement frequency of once every six minutes (10/hour; 125/tidal cycle)
would be compatible with NOS stations. A measurement frequency of once every
15 minutes (4/bour; 60/tidal cycle) would be compatible with the USGS maintained
stations. Existing USGS equipment would permit sampling frequency at the
USGS stations to be increased to every five minutes (12/hour; 150/tidal cycle)
(38), which would permit improved graphic display of tide levels.

----------

Thame
% at Ne
Old Saybrook
-Harbor
New Haven Breakwater

Bridgeport Harbor

Lost
Stamford Harbor

FIGURE 5.1:. Locations oU Permanent Gage Stations for Tide and Storm S
Measurements

5-10

A good quality strain gage pressure sensor is recommended for water level
measurements4, The pressure sensor would be placed on the ocean bottom, approx-
imately 100 feet beyond the south edge of the breakwater. The suggested mounting
for the sensor is a steel pipe tripod, with concrete weights. Cable from
the sensor should be buried in the sediment and secured against the breakwater.
(182,183) Figure 5.2 illustrates a typical installation.

Data T- i and Processing, Data would be telemeteted by VHF radio
to the existing base stations in Hartford and Bloomfield. It is anticipated
that radio signals from all stations could reach the base stations with existing
ASERT re peaters, as shown in Figure 5.35. New repeaters would be installed
if required to get a signal through to the base stations.

Receiv ed data could be processed by the existing Enhanced ALERT software
(61). Stillwater levels could be treated similar to stream level data6
It is recommended, however, that a new software module be developed for the
Enhanced ALERT software to process the tide and storm surge data. This module
would include predicted tide levels for each station using NOS data (Stamford,
Bridgeport and New London) or NOS procedures for determining tide levels (Old
Saybrook and New Haven stations) by correlation with the New London or Bridgeport
stations. Programming should include triggering an audible alarm whenever
actual water levels exceed predicted tide levels by a specified amount (such
as one or two feet). A graphic display, as well as tabulations, of predicted
vs. actual water levels should also be included. Costs of developing this
module are estimated at $@,000 to $10,000 (assume $8,000). Archiving of processed
data would depend on procedures developed for archiving data from the ASERT
system. These procedures have not yet been finalized (184).

4The accuracy .required from a top-of-the-line strain gage pressure sensor
or quartz .,pressure sensor is not essential for stations used to measure only
tide and storm surge.
5This configuratio .n for signal transmission is based on information from topo-
graphic maps. No field checks have been made to confirm signal transmission.
6See for example, Figure.4.9, which is a printout of water level data from
a tide gage in San Francisco Bay, prepared with the Enhanced ALERT software
(61).

5-11

DIPOLE ANTENNA

WEATHER-TIGHT ELECTRONICS BOX

STEEL TOWER
PIER 20'

30'
TRIPOD MOUNT

FIGURE 5.2: Typical Gage StationInstallation

R- t
Z.
_UA6

SR- I

AX3
R- 1

SR-4
12%

9bamoo &Lear. see Leffides

13 old Saybrook Breakwater

Nov Novas larbor

ItUloport 14rbor REPEATER STATIONS IN ASERT SYSTEM

SR-1 Mohawk Mountain Observation Tower
SR-4 Oxford Fire Tower
Stamford lowbor SR-8 Jobn Tom Mountain
.SR-14 Fire Tower on Ekouk Hill
AR-1 Fire Department Radio Tower, Plain Nil
AR-2 DOT Antenna site. Mt. Parnassus
C3 Tide/Storm Gage Station AR-3 DOT Tower, Meriden Road
Radio Path (not field checked) A Base Station

FIGURE 5.3: Radio Telemetry Network

5-13

ALTERNAT13LF DMIGNS

Maximum Use of Existinv' Instrumentation: Alternative 1-a- One alternati
ive
maximizes the use of existing instrumentation at the four recording tide stations
which would be incorporated in the system. Presentlyp these stations 'employ
either bubbler gages or float gages. These same' gages could continue to be
used by installing a mechanical drive to interface the gage with an ASERT
compatible transmitter. The new gage station at New Haven Harbor and the
two roving gages would employ a pressure transducer gage as recommended above.
These gages would require an analog connector to an ASERT compatible transmitter
(176).

Equipment costs for existing stations are estimated at approximately $5tOOO
each, including interface units, transmitter, back-up power supply, cable
and antenna, and meteorological sensors with conditioning electronics and
cable. Costs for new- stations (permanent and roving7) are estimated at approx-
imately $6,500 each,, including the above equipment plus a pressure gage, gage
mounting, and underwater cable. Total equipment cost for the 5 p ermanent
and 2 roving gage stations in this option is approximately $39,500. Including
software costs, the total equipment 'cost, of this option is approximately $47,500.
Installation costs would be approximately $39500.

Upgraded Instmmentatione Alterniltive 1-b A second alternative is to replace
the existing water level sensors with new pressure transducers8. Each station
would be equivalent to the new stations described in Alternative 1-a, with
equipment costs of about $6,500/ station, and a total equipment cost. for the
seven stations of about $45,500. Including software, total equipment cost

7Does not include costs of instrument housing for roving stations, since the
location of these gage stations has not been selected and the.-possible availability
of existing instrument housing is unknown.
8 Replacement of existing equipment will require approvals and coordination
with the agencies that own the tide stations.. Agreements will have to be
reached with NOS for the New London and Bridgeport gages, COE and USGS for -
the Stamford gage, and USGS for the gage at Old Saybrook. Agreements will
also have to be reached with these same agencies for adding interfaces to
the existing gages, and adding the additional meteorological and transmitting
equipment.

5-14

of this alternative is about $53,500. Installation is estimated at about
$5,000.

L= Tide, Storm Surge and Wave Measurements& ASERT Compatiblg
GENERAL NETWORK DIECRIPTIO The addition of wave measurements requires modifi-
cations to gag e station locations, sampling sensors, field station data processing,
data transmission, and data processing. This section describes these changes
as they would apply to, an ASERT compatible network.

Station Lo cations If wave measurements are added to the monitoring network,
a new station must be added at Stamford Harbor (the exis ting station in Stamford
Harbor would 'be dropped from the network)9, and the sensor at the Old Saybrook
station relocated. The new -Stamford station would be located on the West
Breakwater at the entrance to Stamford Harbor. Installation would be similar
to the New Haven station, utilizing an existing Coast Guard lighthouse tower
and mounting a pressure sensor on the ocean.bottom off the south (open water)
side of the breakwater. (182,183) The Old Saybrook station presently has
a bubbler gage located on the protected side of the breakwater (30). The
bubbler gage would be replaced10 with a pressure sensor and relocated to the
open water side of the breakwater. Figure 5.4 shows the location of this
monitoring network.

Instrumentation Collection of wave data requires a higher quality pressure
sensor than is needed for tide and storm surge measurements. A top-of-tbe-
line strain gage pressure sensor or quartz pressure sensor is recommended.
Wave data also. requires more complex. conditioning electronics at the field
station in order to handle the burst samplings required for wave spectral
data in addition to averaged data for stillwater levels.

To obtain the most complete i nformation, wave directional spectra could
also be measured. This would require the installation of wave gage arrays

9
The existing station at the Hurricane Barrier in Stamford Harbor could also
be included in the network, but two stations in the same area are not necessary,
and for purposes of network design and cost estimating it is not included.
1OThe bubbler g age could be kept in operation if desired.

-----------

V'.

\6, Thamc
at N 6
Old Saybrook
New Haven
Harbo.r
Breakwater

Bridgeport Harbor

L'Vaj
Stamford Harbor

FIGURE 5.4% Locations of Permanent Gage Stations for Tide, Storm S
and Wave Measurements

5-16

(three or four gages at one station) or wave gages with built-in wave direction
measurement instrumentation. Because ASERT poses limitations on wave data,
the designs for an ASERT compatible wave network assumes wave gages without
directional capability.

Data Transmission and P The ASERT system was not designed to
handle wave information, and there are no existing installations using ASERT/ALERT
type systems that collect wave data. Nonetheless, it would be possible to
develop a wave monitoring network utilizing the ASERT system, providing certain
compromises in data and/or system quality can be tolerated.

The principal limitation of the. ASERT system to collecting wave data is
the event reporting feature. ASERT/ALERT includes both event and timed reporting.
Relative humidity, temperature, and soil moisture are transmitted on a timed
basis (currently set at once every six hours). Each relative humidity, tempera-
ture, and , soil moisture sensor at all field stations is set to transmit at
a predetermined time, with each sensor transmitting at a different time to
avoid signal interference and loss of data. (67)

Precipitation, streamflow, and wind speed and direction are transmitted
on an event basis (data transmitted only when a reading differs from a previous
reading by a predetermined value). Because event reported data is transmitted
at random times, signal interference may occur at either a repeater station
or a base station. Statistically, the short transmission time (about 1/4
second) for each signal will result in, very few lost units of data, even for
a network with many more sensors that ASERT/ALERT presently has. During storm
events, with strong winds, heavy precipitation and rapid increases in streamflow,
the number of data units lost due to signal interference may significantly
increase. However, signal coding 'and data processing procedures permit all
signals (received or. lost) to be accumulated. Therefore,' total precipitation
and stream, level increase can still be determined, as well as the rate of
occurrence, and little or no, loss of significant data occurs. Similarly,
tide and storm surge, data would. be accumulated, and loss of some individual
data units would not be critical.

5-17

Wave data presents at least three serious conflicts, with the ASERT system.
First, any loss of wave spectral data would mean total loss of useful data
for that sample. Each sample of wave data is largely independent of others
and is not accumulated like rainfall or even storm surge. Second, wave data
requires a much longer transmission A im e than other information on the system.
Third, wave data is normally not collected with 'great frequency (usually only
once every 3 to 6 hours), but during storm periods, an increase in frequency
of measurement is desirable. ASERT has only one-way communications, making
a change in sampling frequency impossible (except by changing at. the field
site, which is not very practicable).

Any design that adds wave measurements to the ASERT system will require
a new software module for the Enhanced ALERT software. Costs for writing
this wave module would varydepending on the type of wave data received at
the base station and the form of display desired. For cost estimating purposes,
a software development cost of $25,000 is assumed.

ALIERNATIVE IIESIGNS

Simplified wave data* Alternative 2-a One way to utilize the ASERT system
is,to collect simplified wave data. Conditioning electronics' at gage stations
could be programmed to sample waves in a different manner than-is normally
done.' For example, the averag e wave height and wave period over a given period
of time could be 'mathematically determined. Transmission of this simplified
data would I require about the same time (less than 1/4 second) as 'other' data
transmissions on the ASERT/ALERT system, reducing chances of interference.
Loss of a data,unit would still mean total loss of wave information for that
time period.

Costs for this alternative are estimated at about $10,000/station for a
total equipment cost of about $70,000. Including sof tware costs, this alternative
would total-about $95,000. Installation costs are estimated at about $5,000.

Field station of spectral MInve data., Alterl]ative 2-h Another
procedure (Alternative 2-b.1) for including wave data on the ASERT* system
would be to collect the full' wave spectra data, but instead of transmitting

5-18

the full data stream, the data could be processed at the field site. Transmital
of processed data would require a much shorter transmission time, reducing
chances of interference. To verify accuracy of the data, some portion (1/8tb)
of the raw data should also be transmitted. Because the data would be processed
at the field station, raw data would not be arcbived for research purpose.
Data transmissions experiencing interference would still be completely lost,
and the transmission time would be longer than otberr?ASERT/ALERT transmissions.

Costs for this alternative would be higher than the previous alternatives
due to the more sophisticated electronics required. An estimate of $12,000/station
is used for a total equipment cost of about $85,000. Including software develop-
ment, this alternative would cost about $110,000. Installation costs are
estimated at about $59000.

A variation on this procedure (Alternative 2-b.2.) would be to collect full
wave spectral data, transmit only significant wave height and significant
wave period (along with stillwater level), and store wave spectral data on
Pagnetic tape at. the gage station. Several wave measurement systems permit
data storage on magnetic tape, and customizing of the conditioning electronics
should permit tape storage as well as radio transmission of stillwater level
and wave height and period. No information was received on a wave gage collec-
tion/storage/transmission unit that performs according to this description,
but customizing of existing units should make this configuration possible.
Storage of wave spectral data on magnetic tape for periodic retrieval would
not adversely affect the flood monitoring network. Spectral data are primarily
useful for research and design purposes, which do not normally require real-
time data.

Costs for this alternative are estimated at about $15,000/station, for
a total equipment cost of about $105,000. Software development should be
less since only water level, wave height and wave period will be provided,
and is estimated at $8,000, for a total cost of $113,000.. Installation costs
would also be about $5,000.

FreQuent Sampling Rate/Multiple Trg Alternative 2-c Still another
procedure to enable. wave data to be included on the ASERT system is to increase

5-19

the sampling rate or to provide multiple transmissions of the same wave'sample.
Either procedure to reduce the consequences of lost data units creates additional
problems by- providing unnecessary data for processing and/or archiving, and
increasing the number of data transmissions, thereby increasing the, overall
rate of interference.

Costs should be about the same as Alternative 2-b.1: $85,000 for equipment
and $25,000 f6r software for a total cost of $110,000. Installation costs
would be about $@,000.

Tide, Storm Surge and Waye Measurements* Two'Networks

Wave data is highly.. desirable for both flood warning and other purposes,
but most alternatives for including wa ve measurements on the ASERT -system
require substantial compromises in either the quality of the wave data or
the overall reliability of the ASERT system. Therefore, another . alternative,
'was explored that would provide wave data and still be partially compatible
with the :ASERT' system. This' alternative requires two separate monitoring
networks: an ASERT compatible tide and storm surge network, and a wave network.
Three options are presented.

GENERAL NETWORK DESCRIPTIO Each option would include an ASERT compatible
tide and storm surge network consisting of only two stations: New London
and Bridgeport. If these two stations are equipped with pressure sensors,
the cost for this portion of each option would be about $13,000, plus $9,000
for software development, for a subtotal of $21,000. The wave network in
each option would include permanent stations at Stamford Harbor Breakwater,
New Haven Harbor Breakwater, and Old Saybrook Breakwater, and two roving stations.

ALTERNATIVR DESI*GNS

One-Way Communications System* Alternative 3-a A separate one-way communi-
cations system could be established which would include new repeater stations
(possibly at the same 'sites as ASERT repeaters), a new decoder/receiver unit
at the base station, and additional radio frequencies. This separate network
would enable transmission of wave' data timed to avoid interference among the

5-20

different gage stations.

Each wave gage station, including pressure sensors with all electronic
conditioning to collect water level and wave data, transmitter, antenna, cables,
meteorological sensors and backup power supply could range from about $12,000
to more than $30,000 depending upon the specific equipment and whether or
not directional wave gages are selected. Repeaters for this system could
range between $7,000 and $11,000, and a receive r/decoder would be approximately
$6,000. For comparative purposes (assuming three repeaters are 'needed), assume
a cost of $130,000 for non-directional wave stations and $180,000 for directional
wave stations (directional gages; not arrays). The total for both networks
(surge and wave) would range from about $150,000 to $200,000. Installation
costs are estimated at about $8,000.

Two-Way Communicationa System., Alternative 3-b Installation of a two-way
communications system would permit operators at the central receiving station
to reprogram wave gages to increase or decrease sampling frequen cy as desired.
This would permit maximum utilization of the wave network during storms.
Costs for this wave network could range from about $250,000 for non-directional
wave stations to .$300,,000 for wave directional stations (directional gages;
not arrays). The total for both networks would range from about $270,000
to $3209000. Installations costs are estimated at about $10,000. The total
for both networks could be as much as $340,000.

Linkage to SIO Wave Monitoring Systemo Alternative 3-c Another alternative
is for the State of Connecticut not to process wave data itself, but to tie
into the SIO wave data collection network. To establish the linkage with
SIO,, wave data would be transmitted over a separate communications system
(as with Alternatives 3-a and 3-b) to the Hartford base station. Received
data would be routed to a microcomputer (or other microprocessor unit with
buffer memory sufficent to temporarily store data from all wave stations)
which is link ed by ,modem to a dedicated phone line. At preset times, the
SIO computer would initiate a, telephone call to the Hartford base station
to receive the most recent data from each wave station and initiate data
processing. Data on significant wave height, significant wave period and
wave spectra would be available to Connecticut users in a few minutes by calling

5-21

the SIO computer via a modem connection. Processed data would be published
monthly by SIO, and additional data processing performed and published annually
(See Figures 5.5 and 5.6).

Although it was not specifically investigated, it is probably feasible
to use the existing ASERT computer and a new module to the enhanced ALERT
software to store data for SIO processing. Presumably, the software module
could also extract water level, significant wave height and significant wave
period data for immediate input into the ASERT system, while passing spectral
data on to the SIO computer for processing. Equipment costs would be about
the same as the two previous alternatives, depending upon choice of one-way
or two-way communications, directional wave gages and other variations in
equipment type and quality:
- One-way communications,. non-directional wave stations: $130,000
- One-way communications, directional wave stations:
- Two-way communications, noir-directional wave stations: $250,000
- Two-way communications, directional wave stations: $300,000
Software development costs are assumed to be about $25,000, and installation
costs would range from about $8,000 to $10,000 depending upon whether one-way
or two-way communications Yere used.

The principal advantage to joining the SIO network is the cost savings
from having all data processing and archiving handled by SIO (and not having
to develop -specialized software, if that option is chosen). The annual savings
in data processing and archiving could be substantial. Another advantage
to the SIO network is that wave data could be easily input to the NWS AFOS
system for distribution to the New York WSFO, Bridgeport and Hartford WSOs,
and other appropriate NWS offices.

There are, however, s ome distinct disadvantages to utilizing.the. SIO network.
Data must be input and @retrieved from the SIO computer system through telephone
lines and modem links, making it somewhat more susceptible to disruption during
storms (both California and Connecticut storms) than a radio based system.
A major. limitation of the SIO system is that water level (tide and storm surge)
is not routinely process,e Id.and reported by the system (ASERT software enhancements
may overcome this limitation). Other disadvantages include dependence upon
another organization for maintaining a significant portion of the total network;

5-22

WAVE ENERGY SPECTRA DEC 1985
- IMPEPIAL REACH ^MAY. DIRECTION
DEC 11POS
APPOULAR DISTRIOUTION IN PERIOD SAMS
MOGLES IN DEGREES)
PST Sze- AM Tur. SKY S-0 PERIOD Ll"ITS ISECR)
DATfT"W (CEO) (CrL 80) 22-SN 10-16 so-34 1@&2 12-10 10-9 9@.

0=1 93.1 -2$7.7 011.1 WX 5 "-& ft.0 ".3 ".5 94,11 87.6
3 1 " 6 91 A 94.6 96-1 97.7 91.0
3401 93. -9&.; Tl@ , 94
& @ *2 9Z 1 92 : 95 7 93 & 9313 94@ 9
7
1 2001 96.0 7 97.0 94.3 94.0 IP3: 919 9Z 7 96, 2 91.0
2 0201 :13-0 -IS-: 77.9 92.3 92.9 90.6 63. 6 93.7 W.2 00.6
4' 96.6 96.11 92- 5 91 2 09.7 9Z 7 93.2 M 2
-29 2 3 291 a 78:3 94, -P 97.2 S& 4 92 3
90.
140, 93'
2 .. as. 1P @l 4 3 :1 9W 2 94.3 93.6 90.0 86:4 2@ I
3 0201 93.0 -437.1 92.2 97.0 ft.6 91.1 W.5 94.6 811.2 37 2
a 000 ft. 9 @113. a 09 1 93 394.0 91.6 94.2 ' ' 67 4 " '
21 a 1401 V2. 7 -*20@ I SIP'2 93:2 M 4 93.7 9Z 5 ql. . 11:2 93.4
3 200t @M 5 -40Z 9 03-9 87.2 96.7 90-2 "- Y03.3 91.4 91.9
4 0201 92.9 -300. 0 04,11 9& 4 'M 2 90. : 90- : 92 29 93. : 97.9
A OWS T& -202- 03' 2 09F 7 6 -M 91 92- 90 87 4
3 3 0 A
'A 4 1401 -03. :279.17 74-, 9z 7 9z 93. 94: 93.. ::: 3 93@ q
4 2001 94. 15Z , 99L 9Z & ".7 92-4 90.9 102. 392.6
Mot -194 7 66.0 %.5 69.3 92.4 Bit- 6 80. 7 -Vt
owl -M-2 a92.50 92 7 94.. -Ft. ? so:
90 2 -91 04.6 96 .91.
3 1401 9Z 3 -139@ 90.9 94:2 92. 94:1 92.3 93.6 9.%5 90 0
3 2004 ".3 -2*3. 3 89.6 96.3 ".0 96-2 91.2 92- 0 94. 394.1
& 0201 ".3 -2". 4 92-5 94@ 9 96.0 94-4 99.6 92. q " 3 ".1
S W01 94. 1-240.2 85-3 92 3 93.2 93.4 ".3 9Z & 95:2 96- 2
1401 92 6 -262-7 -.7 9. 94.4 92-1 92-6 "-b 94.4 95 3
2"1 93.9 -177.4 95.6 93:: 93.3 ".3 93.8 91.9 95@ 3 90.7
7 0201 93.3. -126.3 90 3 ".3 92.1 09.7 94.5 %Z 6 q3 7 95.2
7 0001 "-1 -170.0 91:6 95.0 9Z A 93,7 IM S92 7 92 `3
7 1401 93.7 -21Z 0 110.7 93.9 92.6 96,4 92. 392: , -.: 92-,
7 2001 93.2 -226@ 7 72.3 ".A "@2 93@3 94-3 91.6 91-7 90.4
9 0263 "-2 -= 7 113.0 "-& " ' M 3 94.0 W.3 ".7 405@2
0001 " 3, -1:3 97 4 99 6 q3: 2 94.6 9312 93 -1 913 7 100@ 3
95: -2.1 3 917 09. : 93 2 ":9 " !
20 16 ;2 8 4 9 2001 95.2 -260.4 100.8 94@ .:2, 9,2. 9* 9"4.- 93 9"4: . 99. a q.:
.PERIOD SEC. q 0203 96.7 -211.2 92.8 93.0 93.9 94.9 @M & 97.3 99.2 96.6
IMPERIAL BEACH ARRAY.ENERGY

IMFRIAL 3EAC ARRAI.ENERGY WAVE DIRECTION IN PERIOD BANDS
DEC '983
TO

PERSISTENCE

LMVE MUCHY 19 @ METERS OR LESS
CONSECUTIVE DAYS 41 an WRE) SIGNIFIeWr

METERS DAYS
0 5 1.
1:0 1. 1. T. 5.
1, 3. 10. 7.
2 2 21L
2.5 31:
3.0 2,
3.S 2.:
4.0 21.
4 2

MAPIMM DAILY SIGNIFICAwr MAW Halawr Fw- nee I"M Q

DATE I DEC) I a 3 4 3 A 7
sic. Kr im 1 1.6 Ole z # A.& S-6 1.7 1.9

DATE ( WC I a P 10 A 1 33 94
SIG. Wr (M 3 1.9 L7 1-4 0. V 1.3 1.3 1.2

DATE d WC is 16 17 is 19 20 as
910. HT (PL 0.9 0.3 0-& 0@ 9 0. V 9.4 0.7

DATE C 0=1 22 zz 24-, 23 26 21'
Ole- MY (M ) 1.0 1.1 1.6 1.0 0.9 0.4 0.9 1 22-14 is-Is ID-11 6-6 a--
DATE C DEC) 20 30 31 PERIOD SEC.
ago. HT (PL P 0.9 0.9 1.1 IMPERIAL BEACH ARRAY.OIRECTION

SOURCE: U.S. Army Corps of Engineerst and California Department of Boating
and waterways. 1986. Coastal Data information Program,, Monthly
Report, December 1985. Monthly summary Report No. 119.

F IGURE 5.5: Examples Gf Monthly Wave Data; West Coast Wave
Measurement Network

5-23

IMPERIRL BERCH ARRRY. DIRECTION
IMPERIAL BEACH JAN-DEC 1984 ANNURL ORTR 1584

BSC

W"WRLY TRWFW

SWTWMY TRARPM

I%p k.

JOINT DISTRIBUTION OF HEIGHT & PERIOD

MKnfMY TRANSPOU

IMPERIRL BEFICH RRRRY. DIRECTION
ZTA 1384

Onnfmy rmnpw

d TMPERIAL BEACH JAN-DEC 1984

0
1167 11@ UL 0.1aw

4.
to a
to 0
JAN FEB' MAR' APR MAY JUN

WWI

2
'we ai U01a
64
0.
JUL AUG SEP OCT NOV DEC

SEASONAL SIGNIFICANT HEIGHTS OF SEA & SWELL

SOURCE: Seymour, R.J., et. al. 1985. Coastal Data information Program,
Ninth Annual Report, January 1984 through December 19,84. Scripps
institute of Oceanography, La Jolla, CA.

FIGURE 5.6:. Examples of Yearly Wave Data; West Coast Wave
Measurement Network

5-24

access to the data by telephone, including associated telephone charges; and
uncertainty over-the costs of participating in the network1l.

Tide, Storm Surge and Wave Measurements: Independent from
ASERT* Alternative

The last alternative presented is for a monitoring network that is entirely
independent of ASERT and provides a maximum of information. T his network
would maintain the same station locations as described for alternatives 2,
3, and 41 2, and use a two-way communications system.' Instead of using the
ASERT base station. computer and software, a separate data processing system
would be installed, at the base station. Equipment costs for this network
are estimated at about $425,000, and installation costs at about $15,000.

IMPLEMENTA110N OF MONITORING NETWORK

Estahlisbment of Gage Stations
Depending upon the monitoring network design chosen, the State has several
options and some limitations regarding the sequence and timing of implementation.
Because of differences in equipment at existing systems and differences in
timing of converting to new equipment, the entire monitoring network probably
cannot be installed with its final configuration immediately. The installation
may need to proceed over a period of several years in order to coordinate
actions and establish interagency agreements with several federal agencies.
Some temporary , installations may be needed. Following are some suggested

11Presently, California is the only state making a financial contribution to
the SIO network. In recent years California has been contributing $50,000/year
and is expected to increase its contribution to $100,000/ year in FY 87. (135)
Certainly, Connecticut would not need to' contribute this large an amount,
but an acceptable amount would have to be worked out between the State and
SIO (and probably the COE and State of California).
12The NOS stations at New London and Bridgeport could be replaced with stations
in the same areas, but in open water to obtain wave measurements along the
shore rather than in the Thames River estuary and Bridgeport Harbor. Locations
for these new. stations have not been identified, and no cost estimates for
this alternative were developed.

5-25

State actions.

Dev elop a cooperative agreement with the NOS to have the New London
station included in the early group of next generation tide gages
to be installed. Assuming that NOS proceeds with a primary acoustic
gage and a backup pressure gagel3, arrangements should be made to
add the pressure gage to the Connecticut flood monitoring network.

(2) Develop a cooperative agreement with both NOS and NWS to use the NOS
g age at -Bridgeport Harbor on a temporary basis until NOS upgrades
this station with new gagesl4,

(3) Develop an agreement with the Coast Guard for continued use of a gage
station at the Sayboook Breakwater and new gage stations at the New
Haven and Stamford Breakwaters (assuming wave stations are selected).

(4) Modify the existing agreement with USGS, for operation and maintenance
of the gage station at Old Saybrook to provide for upgrading the sensor
(tide/surge or tide/surge/wave), if that option is chosen, as well
as maintaining the new wave gage stations at New Haven and Stamford.

(5) If a tide/storm surge only alternative is selected, develop an agreement
with the COE and USGS for upgrade and/or use of a gage station at
the Stamford Hurricane Barrier.

(6) Hold discussions with coastal communities, DEP Water Compliance Unit,
UCONN researchers, and Connecticut DOT, Bureau of Waterways to identify
locations that would receive high priority for initial placement of
the two roving gages. Proceed with deployment of the two "roving"
gages.

Getting Information to Users

Getting- tide, storm surge, wave and meteorological, data to essential users
is just a s important as collecting the information. For efficient use of
the monitoring networkq three user groups need to receive information in real-
or near real-time: State emergency officials (OCP and CSP), NWS, and officials
of c oastal municipalities. Real-time information would be highly desirable
for at least two additional groups: Coast Guard and -various navigation interests,

13
There appears to be some uncertainty as to whether NOS will actually install
a backup pressure. gage. If not, the Connecticut network could utilize. the
acoustic gage.
141t may be nee essary or desi rable to have the Connecticut monitoring network
link directly with the NWS telemetry unit (HANDAR Model 540A).

5--26

own base station and associated software, just as communities are presently
doing for the ALERT system.

In order for communities to purchase their own base station, costs must
be reasonable and the information must be produced in a format that is easy
to understand and use. If a double- network (tide/storm surge network and
wave network) requiring two different communications systems is selected by
the State, equipment costs for municipalities will increase; antenna(s) and
receiver(s) must be capable of receiving multiple radio frequencies.

NAVIGAT ION INTERESTS AND OTHER USE If tide, storm surge and wave data are
easily available and reliable, harbor pilots and others involved in shipping
could benefit from real-time data from the coastal monitoring network. Navigation
users could access the information in several ways:
(1) Installation of 'a base station at offices' of the different harbor
pilots associations, marinas, etc. Harbor pilots on ships could contact
the association office to obtain current information on water levels
and wave heights.

(2) Use of a remote terminal (modem with printout or display) at the pilots
offices, marinas -and other locations to access data from the Hartford
base station by telephone, and relay to shipboard users. If the Hartford
base station were equipped with a voice synthesizer, information could
be accessed by telephone without need for a remote terminal.

(3) In the near future products should be available to permit shipboard
use of a remote terminal (modem with printout or display) or portable
computer with modem to access information from the Hartford base station
via cellular telephone. Cellular telephone coverage now includes
the entire Connecticut coast except the Groton/Stonington area, which
should be added during 1986. (180)

MAINTENANCE PROGRA

Constant or periodic exposure of equipment to saltwater or saltwater spray
promotes rapid corrosion. Equipment can degrade rapidly under these conditions.
As a consequence, the coastal flood monitoring network must be maintained
with care and diligence.

5-27

There are many possibilities for weak links in marine systems, and care
must be taken to eliminate these weak links. For example, lack of care in
mating cables, or in selection of nuts, bolts, etc., can result in extensive
repair costs. Attention to such detail during design and installation can
minimize the maintenance requirements of the system.' Thus, in accepting any
components related to the coastal monitoring network, emphasis must be placed
on durability, ability to withstand large -waves and high water, and resistance
to corrosion. ' Altbough a -tentative maintenance schedule is presented for
consideration with this report, final maintenance procedures will be a function
of product reliability, construction techniques, and care during installation.

Maintenance J!rogram

A complete and active maintenance program needs to be developed and rigorously
adhered to. It is recommended that one individual be assigned responsibility
for the maintenance program. This will, pr.ov ide continuity in the maintenance
program, and build familiarity with the system. Similarly, it is recommended
that the individual(s) assigned to the maintenance team(s) be given long-term
assignments or contracts.

A* tr ouble-sbooting sequence should be established by either the State or
a contractor, to facilitate rapid isolation of any system'modules causing
a problem. For example, a procedure should be mapped that will allow discrimina-
tion between problems caused at a gaging station, versus those-caused at a
repeater, versus those caused at a base station. Office tests may help isolate
the module at a remote site which is in need of repair, thereby minimizing
field testing at remote sites. This type of discrimination is necessary to
reduce the time required of field crews, training of field crews in the electronic,
communications and mechanical aspects of the system, -and to reduce system
down time. Spare modules can be purchased to allow rapi d correction of problems,
with the suspect modules later replaced or repaired.

Inspection teams s hould accomplish minor repairs Irepairs taking less than
one hour, not requiring major pieces of equipment, nor requiring special 'skills)
during regular inspections. Each team should have with them a tool and spare*
parts box with essential equipment needed to accomplish minor repairs.

5-28

especially shippers and harbor pilots.

STATE EMERGENCY OFFICIALS The ASERT base station is presently located in
the offices of the DEP Water Resources Unit in the State Office Building.
The two State Warning Points, OCP and CSP, do not presently have direct access
to the ASERT system. To ensure proper coordination among all State emergency
officials, local officials and NWS offices during times of potential flooding,
it is important that both OCP and CSP have direct access to real-time data
on coastal (and riverine) flooding. The radio signals which reach the State
Office Building should also reach both OCP and CSP, which are in the same
vicinity. Therefore, it is suggested that both OCP and CSP acquire their
own base stations.

NATIONAL WEATHER SERVICE The essential NWS stations are the New York WSFO
and the Bridgeport and Hartford WSOs. One option would be for each of these
offices to install their own base station and receive data directly by radio
transmission, just as the NERFC office in Bloomfield now does. However, it
may not be possible for the New York WSFO to receive ASERT radio signals from
Connecticut due to interference from many other more powerful signals in New
York City (185). It would also be highly desirable for the National Meteorological
Center in Silver Springs, MD and the National Hurricane Center in Coral Gables,
FL to also receive real-time data from the Connecticut coastal monitoring
network. To do so, the information needs to be added to the NWS AFOS system,
which all of the concerned NWS offices have. The AFOS system i s apparently
being used to capacity, and specific authorization must be obtained to input
additional information to the system. It is also not clear just bow ASERT
data would be entered into AFOS. (32,36,68,185,186) Clearly, some automated
procedure is needed. The most logical entry point appears to be the NERFC
in Bloomfield or . the Hartford WSO at Bradley Field, Windsor Locks. The. State
and NWS need to pursue the autborization.and procedures for getting ASERT
data into the NWS AFOS system.

MUNICIPAL OFFTCIALS Municipal officials who wish to use the coastal monitoring
network to obtain detailed, geographic specific information on actual storm
surge and wave levels must also have direct access to the ASERT system. The
most efficient, procedure appears to be for local communities to purchase their

5-29

For all inspections procedures described below, a written report should
be prepared immediately by the maintenance team and submitted to the program
manager, including any repairs or maintenance performed by the team and any
problems noted that require further attention. The program manager should
evaluate these reports and arrange for immediate r epair or replacement of
equipment, as needed.

Maintenaneg Schedule

A matrix of maintenance procedures is presented as Table 5.2.. Each aspect
of the four maintenance procedures is discussed below.'

MAINT WCEDURE1 All data should be monitored carefully by the Program
Manager to detect any hardw are- related problems. Any problems identified
can be evaluated more carefully during monthly on-site inspections*'

All above-water portions of the system should be inspected visually each
month. All hardware should be. inspected for structural damage and corrosion.
Connectors and mating parts should be verified for stability, and clamping
hardware should be checked for tightness and integrity. Corrosion of metal
materials must be identified and arrested early to avoid catastrophic failures.
If any damage or decay is noted, prompt action should be, taken to avoid later
failures that could result in extensive down time. Records should be kept
to document a history of failures and corroding parts.

The remote backup power supply should be tested at this time. Magnitude
of charge and integrity of charging circuitry should be ev aluated. If necessary,
the battery can be cycled during this- inspection.

Clocks should be r eset and synchronized, using a portable master clock
or radio re ceiver.' A log of clock errors should be kept at'each station to
permit a history of clock behavior.' Excessive drift or decay of the accuracy
of the time base can be used to indicate need for' clock repla .cement or modifica-
tion.

5-30
The inspection sho'
uld be fairly rapid, taking approximately 1.0 to 1.5
hours if no defects are detected. Repairs of any extensive nature might be
better made during a return 'visit, following approval by the Program Manager.

MAINTEN CFDURF 9 Maintenance procedure 2 is a complete visual check
and servicing of all underwater components. This maintenance must be done
by diving teams familiar with the operation, unless some deployment scheme
is devised whereby - divers are not required. Divers can initiate inspections
from the shore or a small boat, traveling between sites over land.

Crews making these checks of underwater components must be familiar with
corrosion problems and common modes of underwater failures. All connectors,
penetrators, splices and other fastenings and joints should be inspected.
Marine fouling should be removed mechanically, and anti-biofouling paints
or coatings should be applied if possible. . All zinc anodes should be replaced,
and the installation inspected for points of weakness, from both a structural
and a corrosion standpoint. Cable condition should be assessed, and the strain
relief examined for security. Any breaks, kinks, or other damage to the cable
should be noted for proper action.

The extent of scouring and undermining of the underwater mounting should
be determined. Is the tripod sinking or scouring, or is the pipe becoming
too exposed? The pressure sensor should be inspected, noting corrosion or
pitting. Pressure sensor ports should be cleaned, and filled with oil (if
applicable). Any problems in these components should be attended to immediately.

MAINTENANCE PROCFDURF 3 Maintenance procedure 3 includes a close visual inspection
of the electronics at the remote site, measurement of output signal strengths,
and general evaluation of all above-water electronic components. Parts with
known limited lifetime should be replaced. All antenna fastening and structural
bracing should be inspected and replaced, if damage or decay is severe. The
power backup system ' should be inspected and serviced completely (water level
in batteries adjusted, operation of power back-up should be noted when unit
is powered down, then up, and condi tion of terminals noted before cleaning
terminals).

5-31

The weather-tight housing should be inspected for weak points or decay.
All time-keeping circuits should be reset, and any manufacturer-suggested
electronic tests of encoding/decoding and telemetry products should be performed
at this time. Signal strength measurements of telemetry power output and
receiver sensitivity should be in accordance with manufacturer specifications.
Any problems should be tended to immediately.

MAINTENANCE PROCRDURF_4 Maintenance procedure 4 involves complete reconditioning
of all underwater components (with the exception of the cable, which should
be left buried as long as it is working properly). It should be accomplished
from sea on a diver support vessel that has enough enclosed space to refit
hardware onto new tripods inside the vessel as. it travels to the next site.
The vessel must have sufficient lifting capability to retrieve and deploy
tripods with instruments. To accomplish this reconditioning, all underwater
componenets except cable should be retrieved, and replaced by completely recon7
ditioned components. The tripod or mounting pipe should be replaced by a
clean, newly conditioned one with anti-fouling added, the strain termination
should be replaced, and the pressure sensor calibrated thoroughly.

At this time a thorough evaluation of the installation and maintenance
procedures should be made. Weak points should be identified, and corrected.
An evaluation of the long-term potential for decay or corrosion is useful
at this point. Should any components,be redesigned to allow better performance
or wear? Should any element of the maintenance procedure be changed?

Maintenance Costs

The exact maintenance costs will depend upon the specific monitoring network
chosen by the State. The cost estimates shown in Tabel 5.3 are only approximw-
tions, based on the above maintenance procedures for 7 gage installati ohs,
2 repeaters, and 2 base stations. Only maintenance which directly concerns
the electronic components of the monitoring network is included; it does not
include activities necessary to maintain the piers, buildings,or grounds that
are used as a platform for the network.

5-32

TIME BETWEEN MAINTENANCE

STATI I Month I Year 5 Years

All coastal MP-1 MP-2,3 MP 4
gage stations

Repeaters MP-1 M P-3

Receivers M P-1 MP-3

Note: MP maintenance procedure, see text. These procedures are suggested
to assure high data quality. They should be updated in consultation with
the equipment manufacturer and installer.

TABLE 5.2: SAMPLE MAINTENANCE SCHEDULE

Maintenance Coats/Month Cosjs/Year Expendable One-Time
Procedure Parts & Equip Equipment
Per Year
Surface Maintenance

M P-1 $ Soo $9,600
$ 500(l) $5,000(2)
MP-3 11600

Underwater Maintenance

M P-2 3,000 500(1) -

MP-4 4,000(3) 600(4) 59000(5)
(20,000/5 years) (3,000/5 years)

TOTALS $18,200 $4,000 $10,000

W Miscellaneous spare parts such as clamps, nuts, bolts, paint, etc.
(2) Field testing equipment
(3) Includes rental of diving vessel
(4) Includes replacement parts and reconditioning of parts
(5) Includes replacement parts such as pressure cases, pressure sensor,
etc.

TABLE 5.3: ESTIMATED MAINTENANCE COSTS

6-1

6,0e CQNCL,USIONS AND RECOMMENDATIONS

Evaluation of t he information presented in the previous sections resulted
in four general conclusions and related recommendtions regarding the most
favorable design for a coastal flood monitoring- network and the feasibility
of a State forecast and warning system. Each of these . general conclusions
and recommendatins, along with additional specific conclusions and recommendtions
are detailed in this secton.

Li EXISTING MONITQRING, FORECAST AND SYSTEMS

o CONCLUSION # I The present system of 'collecting data, preparing forecasts
and issuing warnings for coastal storms and flooding is less than optimal.

Planned Improvements to Exir2ting Technology and Programs

One option available to the State is to continue 'relying upon the existing
coastal f lood monitoring and warning systems, includi ing improvements to the
existing systems and programs that are already underway or planned.

Conclusion 0 la Planned program changes by several federal agencies
should result in.. gradual and limited improvements to the collection of
meteorological and oceanographic data and to issuance of coastal flood
forecasts and warnings.
The most relevant of these planned improvements are summarized belowl.

(1) Hurricane Preparedness- Studigs,, NWS, FEMA, and the COE proceed
with their program of Hurricane Preparedness Studies, utilizing results
from the SLOSH model. Information on projected storm surge heights and
areas to be innundated from different categories of storms should be available
for the eastern portions of LIS and the Connecticut shore beginning in
1987, following completion of storm simulations and 'development of MEOWS
for the Narrangans e t t/ Buzzards Bay SLOSH bas 'in. More.detailed delineation
of storm surge and innundation areas for the entire Connecticut coast should

lNo attempt has been made in this report to consider the potential impacts
of possible major @cutbacks in federal program budgets. State- officials must
consider these possible impacts in making decisions.

672

be available sometime after 1987 when studies for the New York/Long Island
Sound SLOSH basin are completed. Once information for these two SLOSH
basins is available, the State and local communities will be able to issue
more precise evacuation notices to coastal residents for hurricanes.

(2) NW5 Real-Time Data at Selected Tide Stations The NWS will proceed
with its program of temporarily upgrading telemetry at selected NOS tide
gage stations, including Bridgeport, CT. Implementation of this program
will increase the speed with which storm surge data is received by NWS
forecast offices in Silver Springs and New York City, thereby enabling
improved forecasts of storm surge for extratropical storms. The availability
of this data should also permit an improvement in the establisbment of
boundary conditions for real-time runs of the.SLOSH model.

(3) NOS KGWLMS Program. The NOS will probably proceed with its program
of installing a new generation of tide level gages, including the stations
at New London and Bridgeport. Eventually, this information will also be
available to the NWS to help with improved storm surge forecasts. There
is no clear time schedule for installation of the new gages, or for use
of the data by the NWS.

OpDortunities to Further Enhance Existing Programs

Each of the above programs is likely to proceed without any special effort
by the State. However, by being fully aware of these programs and maintaining
or establishing communication with the appropriate federal agency offices
and individuals, the State may be able to influence somewhat the time at which
some program actions are initiated and the degree to which they benefit Connee-
ticut.

Conclusion 1b; The State can work with federal agencies to maximize
the benefits of federal programs for'Connecticut and LIS.

0 RFMMM -@L-The State should take an active role in working with
federal agencies to take maximum advantage, of existing programs, and especially
- program improvements underway or planned.

Recommendation # le: , The State should indicate to the th ree federal
agencies (NWS, FEMA and COE) involved with Hurricane Preparedness Studies
that it desires to have the Hurricane Preparedness Study for, the New York/Long
Island Sound SLOSH basin initiated as soon as possible. Joint action with
the State of New York in requesting a high priority for initiation of this
study should be considered.

Recommendation # 1 State representatives should inquire with appropriate
NWS officials regarding the specific schedule for installation of the new
NWS telemetry instruments at the Bridgeport WSO, and encourage rapid instal-
lation if it has not yet occurred.

6-3

E , MMENDATION # I The State should explore further with NOS the,
possibility of a cooperative agreement or other arrangement which would
permit early installation of one of the next generation tide level gages
in Connecticut. The New London gage site would be the most logical choice
because of the pending NWS telemetry upgrade at the Bridgeport gage site.

6AJ,a Achievement of State Ubjectives Through Existing PrograMS
Conclusion # 1c; Existing systems and programs, even with planned improve-
ments, will not meet all of the State's objectives for better flood warnings
and reduced losses.

Reliance upon existing systems and programs to collect coastal flood data
and to prepare coastal flood forecasts and warnings will require no extraordinary
expenditures by the State, and some improvements over present conditions can
be expected, such as:

(1) NWS use of near real-time storm, surge data from the two NOS stations
in Connecticut (and other locations outside Connecticut) may result in
small improvements to:

a* storm surge forecasts for extratropical storms, and
b. storm surge forecasts for hurricanes and tropical storms by providing
improved data for establishment of boundary conditions f or the SLOSH
model.

@2) The development of MEOWs from SLOSH simulations should significantly
improve the accuracy of evacuation notices for hurricanes.

(3) The availability of near real-time storm surge data f rom the two NOS
stations in Connecticut could improve the accuracy. and timeliness of local
evacuation notices for tropical and extratropical storms (if NWS includes
actual storm surge elevations in its regular marine weather bulletins and
flood warnings).
However, even with scheduled improvements in federal monitoring and fore-
cast/warning prog Irams, not all of the State's objectives may be achieved.

@1) There will be no additional data on wave action, and no improvements
in wave forecasts.

(2) The geographic coverage of storm surge data will not be increased:
the number of coastal data stations will remain the same.

3) Near'real-time storm surge data will be Avilable only for two locations:
New London and Bridgeport.

6-4

NEW PROGRAMS AND ADDITIONAL IMPROVEMENTS TO EXISTING PROGRAMS

o CONCLUSION 2 To provide better coastal flood warnings and to reduce
flood losses, new programs and substantial improvements to existing programs
beyond those already underway or planned - are needed.

Although improvements to all aspects of the present system are certainly
possible, not all are equally feasible at the present time, nor will potential
improvements in each area yield'equal results in reducing flood losses.

Conclusion # 2a Only limited improvements appear feasible to the existing
NWS forecast and warning system for hurricanes and tropical storms. Further,
because hurricane warnings are already conservative (i.e. attempt to warn
of the most severe likely impact), limited improvements will probably have
little effect on reducing flood losses, especially in Connecticut where
the coastal flood zone is relatively small.

Conclusion # 2b Significant improvements appear possible in forecasts
of storm surge in LIS due to extratropical storms.

Conclu sion # 2c Significant improvements also appear possible in forecasts
of waves in LIS due to extratropical storms and during non-storm condi-
tions..

Conclusion # 2d Significant improvements in the data base for making
storm surge and wave forecasts i,s feasible.

Conclusion # 2e Improvements in information needed for local decisionmaking
and actions is feasible by supplementing NWS regional forecasts and warnings
with more precise real-time information for specific geographic areas.

o R=MMR@MATION* The State should initiate actions which will result
in improved forecasts and warnings.

RecommendLition # 2a: State initiatives should enhance the capabilities
of federal agencies to prepare regional forecasts and warning.
RecUmmendgtion # 2b: State "initiativesIshould supplement regional f ederal
regional responsibilities with more detailed information in specific geographic
areas regarding the extent and timing of anticipated flooding.

Recommendation # 9c- State Initiatives should non duDlicate federal
programs and responsibilities.

Reegmmp,ndation # 2d The State should not issue information that copfliets
with NWS forecasts and warnings.

6-5

REAL-TI M FLOOD MONITORING NETWOBE,

o CONCLUSION # 3 There would be both immediate and long-term benefits
from a real-time: coastal flood monitoring network established by the State
of Connecticut.

A monitoring network would make poss-ible improvements in coastal flood
forecasts and warnings beyond that possi ble with existing systems, and would
provide data important for other uses (see Table.1.1).

o RECOMMENDATION #-I.. The State should p roce ed witb development of a real-time
coastal flood monitoring network

Upe of Monitoring Network

Many alternative monitoring network' de signs are feasible, each possessing
different capabilities and costs.

(1) A monitoring network capable of providing real-time data on tides
and storm surge (and meteorological parameters) and that is compatible
with the ASERT system is feasible.

(2) Collection of real-time wave data, while providing important information
for flood warnings and other uses,, would not be totally compatible
with the ASERT system.

(3) A monitoring network capable of providing -real-time data on tides,.
storm surge and waves- (and meteorological parameters) is feasible,
but would be completely independent of ASERT.

(4) Costs for a re al-time monitoring network would range:from approximately
$50,000 for an ASERT compatible network collecting only tide, storm
surge and meteorological data, to over $400,000 for an independent
network with two-way communications collecting data on tides, storm
surge, waves and meteorological @ parameters.

Recommendation 3a: If the State determines that low cost and full
ASERT compatibility are higher priorities than collection of wave data,
it should develop a monitoring network for tide, storm surge, and meteorological
parameters with one-way communications, similar tothat described in Alternative
1-b

Recommendation 4 3 N If the State determines.tbat cost and ASERT compat-
ibility are not major considerations, but complete wave data is important,
it should develop a monitoring network for tide, storm surge, wave energy
and direction spectra, and meteorological parameters with two-way communica-
tions, similar to Alternative 3b or 4.

6-6

Recommendation 3c; If the State desires to balance costs and system
performance, it should develop a monitoring network for tide, storm surge,
wave energy spectra, and meteorological parameters with one-way communications,
similar to Alternative 2b.2.

Recommendation # 3d: Because of the variable quality and - type of instru-
mentation available, persons experiencied in oceanographic and meteorological
data collection, transmission and processing should be involved in the
final choice of a vendor and contractor for installation.

Recommendation # 3e: The Committee on'Automated Flood Marning should
work with local communities, the research community, federal agencies,
and DEP program offices to identify priority sites for initial installation
of the two recommended roving gages.

fi,= Use of Date From Real-Time Monitoring Network

Conclusion # U Real-time storm surge, wave, wind, and barometric pressure
data from points along the Connecticut coast would enable NWS forecasters
to improve both forecasts and bulletins of actual weather conditions.

Conclusion # 3b; Geographically specific and accurate information on
actual vs. forecast storm surge and wave heights would permit local officials
and residents to make improved decisions and take appropriate and timely
actions to protect property from flood losses.

Recommendation # 3f; The State should work with local NWS weather services
offices and the NWS Eastern Region Headquarters at Garden City, NY to arrange
for data from the monitoring network to be input to the NWS AFOS system.

Recommendation # 3r: A base station should be established in the offices
of the two State Warning Points - Off ice of Civil Preparedness and Connecticut
State Police. These offices should relay data to the Regional OCP offices
and municipalities without their own base stations.

Recommendation # 3b: The State should assist local municipalities in
setting up their own base -stations and properly interpreting data from
the monitoring network.

Recommendlition # 3i; The State should provide a modem connection or
voice synthesizer to a dedicated telephone line(s) to enable users without
a complete base station to obtain data on a call-up basis.

FORECASTS AND WARDIINGS FOR STORM SURGE AND WAVES

6-7

0 DN 4 4 -A State-run coastal 'flood forecast and warning system
while technically feasible -- does not offer significant advantages
over continued reliance on the NWS.
Conclusion # 4a: Storm surge and wave height forecasts cannot be accurately
developed based solely on a local monitoring network.

Conclusion # 4b: NWS models and procedures for extratropieal storm surge
forecasts *and 'wave forecasts are not state-of-the-art and are not designed
specif ically for LIS.
Conclusion # 4c There i s no extensive data' establishing the accuracy
or inaccuracy of NWS forecasts.

Conclusion # 4d; Complex mathematical, models utilizing both local and
regional data are needed to accurately forecast storm surge and waves.

Conclusion 4e: Development and operation of these models would be
expensive more expensive for the State than the NWS because NWS already
has an operational computerized database.'

Qgnclusion # U State forecasts, if differenf from those of NWS, could
create confusion and inaction by local officials and residents during
emergencies.

0 MMENDATION A Instead of developing its own flood forecast system,
the State should work closely with the NWS and other federal agencies to
improve their ability to provide accurate and timely coastal flood forecasts
for Long Island Sound and the Connecticut coast.

Recommendation 44 4a The State should request that NWS develop a new
model for forecasting wave heights in Long Island Sound. This should be
a model designed specifically for LIS, accounting for the shallow water
conditions and other factors peculiar to LIS. Ideally this model would
forecast both open water waves and near shore waves. The model would be
utilized by the New York WSFO.

Recommendation # 4b The State should request that NWS develop a new
model for forecasting storm surge for extratropical storms in LIS. Ideally
a numerical model specific. to LIS could be developed to replace the empirical
model now used by NWS.

Recommendations # Ao The State should consider seeking cooperation
from Rhode Island and New York State (especially Nassau, Suffolk and West-
chester Counties) when requesting NWS to develop new models.

Reco mendation # 4d: The State should work with the New York, Bridgeport
and Hartford weather service offices to ensure that,, as soon as data from
the the Connecticut monitoring network are available to NWS in near real-time,
NWS will include the actual as well as forecast storm surge (and wave infor-
mation if available) in its weather forecasts and warnings for marine and
coastal areas.

6-8

RecommendAtions # 4e: The State should also establish a program to monitor,
through the monitoring network and observations, actual storm surge and
wave heights relative to NWS forecasts. In the event that monitoring of
NWS forecasts and warnings should show them to be seriously and consis-
tently inaccurate, then the State could more actively consider developing
its own forecast and warning program.

RecommendUtion The State should work closely with FEMA, NHC and
the COE in preparation of MEOW's and innundation maps for LIS to ensure
the highest accuracy and greatest applicability.

Recl2mmendatio ns 4 4g: The SLOSH MEOW's and associated innundation. maps
should be evaluated to determine if they can also be applied (directly
or modified) for use during extratropical storms.

"PENDICES

A-1

APPENDIX A: ASERT SPECIFICATIONS

The statewide automated f lood. warning system is called ASERT (Automated
State Evaluation in Real Time).. The initial phase of the ASERT system is now
being installed and should be operational in late 1986. The system consists of 20
automated -rain gages, 6 weather stations (including precipitation gages), 6 radio
signal repeaters,. and 2 base stations. Each base station includes an antenna,
radio signal receiver, data decoder, m'icrocomputer, ALERT software, and an
uninterruptable power.supply backup.

An automated coastal monitoring network that is compatible with the ASERT
ystem will need to be compatible with and make use of the radio signal repeaters
and base station components of the ASERT system.

The specifications provided on the following pages are taken from two sources:
1. Specifications for remote station :transmitters and radio Isignal repeaters
are taken from the bid specifications prepared by the Connecticut Department
of Environmental Protection and the Federal Soil Conservation Service in 1984.
Some modifications to these specifications have been made and other
modifications may be made before the system is completely operational.
Because some changes may still occur, no attempt was made to update the bid
specifications to include any changes that have been made.

2. Specifications for the base station components are taken from product
literature of Sierra Misco, Inc. which supplied all _major base station
components except for the microcomputer.

A- 2

MATERIAL SPECIFICATION

624. TRANSMITTER

1 SCOPE

This specification covers the quality of the transmitter for the automated
gages. The transmitter shall transmit data in a format readable by a
Sierra-Misco Model 5051 receiver-decoder.

2. TRANSMITTER

a) Sensor 'input signals are analog 0-5V DC signal -using digital SPDT
switch contacts.

b) Signal transmitted in binary format consistent with NWS decoding
software.

c) Transmission time of 230 milliseconds.

d) Sends 4.digit station ID.
e) Has 2 digitor greater accumulator (00 to 99) which is automatically
resettable and counts up and@down.

@f) Input channels of 4 digits and 16 analogs.
g). Rechargeable gel cell battery to provide adequate power for one
years' operation. If recharging is needed during the year, a solar
panel or AC power, where available, will be used.
h) Frequency stability of 0.0005%.'

i) Operates in a temperature range of -300C to-600C.

j) Audio distortion of less than 8%.
Q. The transmitter shall have sufficient output to pass the acceptance
test.

1) Generates 2 test signals every 24 hours.

A- 3

3. FREQUENCIES
Repeaters & Gages Receiving Transmitting

Mohawk Mountain 171.875 :169.425
Thomaston 171.875
New Milford 171.875.
Barkhamsted 171.875
Norfolk 171.875
Sharon 171.875

Oxford 169.525 171.125
New Haven 169.525
Stratford 169.525
Oxford 169.525
Bethel 169.525

Southington Mt. 171.125 169.425
Plainville 171.125
Wallingford 171.125
Southington (Prec)
Sewer Plant 171.125
Southington (River) 171.125
Southington (Precip),
New Britian Reservoir 171.125

John-Tom Mountain 171.850 169.425
Mansfield J71.850
Ell ington

Ekonk Mountain 169.475 171.850
North Stonington 169.475
Plainfield 169.475
Thompson 169.475

Plain Hill (Norwich) 171.125 169.475
Salem 171.125
Lebanon (Bartlett Brook) 171.125
Norwich (Prec W 171.125
Norwich (River 171.125
Lebanon (Susquetonscut-
Brook) 1-71.125
Lebanon (Deep River) 171.125

Mount Parnassus 169,525 171.850
Old Saybrook 169.525
Haddam 169.525

Direct to base stations
John-Tom Precip 169.425

A-4

4. GENERAL

a) Moisture protected electronics located below ground.

b) Transmission at 300 baud consisting of four ten-bit words, including
start and stop bits. Transmission interval of less than one-quarte.r
second. This shall include transmitter warm-up period suitable for
operation through a minimum of two radio relays.

c) Data transmission shall utilize binary format consistent with NWS
decoding software - see attachment.

d) An integral programmable clock which triggers regular check signals
for verification of system operation.

e) An automatic regulator which prevents a transmitter from remaining
on.

f) Modular components capable of field swapping.

g) A selectable station ID on the electronic package.

h) Integration of the electronics and power supply into a single
portable package weighing not more than 15 pounds, which is' water
resistant and will float in the base of the gage if it becomes
flooded.
I' I
i) A carrying handle on the electronics package designed to allow
fastening of the lifting rope without blocking hand entry.

All transmitters shall comply with FCC type acceptance criteria.

A-5
MATERIAL SPECIFICATION

622. REPEATERS

1. SCOPE'

This specification covers the quality of the self-contained automated
repeater.

2. VHF RECEIVER

a) A DC rechargeable, gel cell battery to provide adequate power for
one year's operation. If recharging is needed during the year,
AC power will be available for trickle charging.-
b) Sensitivity of 12dB SINAD 0.35 microv olts and 20 dB quieting 0.50
microvolts.

c) Frequency stability of 0.0005% from -300C to 600C.

d) Modulation acceptance of 7KHz.
e) 3.04B gain VHFomnidirectional receivi.ng antenna.
f) Antenna input impedance of $'0 ohms.

3. VHF TRANSMITTER

a) A'DC rechargeable gel cell battery to provide adequate power for
one year's operation. If recharging is needed--during the year,
AC power will be available for trickle charging.

b) Frequency stability of �0.0005% from -30*C to 60*C.

c) 7 dB Directional antenna except'at Plain Hill which shall be a.3 db
Omni directional antenna.

d) Power output shall be at least 25 watts.

4. GENERAL

a) All connections and low loss coax cables, as well. as s'ide mount
hardware where needed, necessary to receive and transmit,the
required signal. All mounting hardware shall be stainless steel.
b) Time to receive and retransmit signal shall be less than-
20 milliseconds.

625. RADIO FREQUENCY FILTER

SCOPE

This specification covers the quality of the radio frequency filter at
the repeater sites.

2. FILTER

A Decibel Products D84002-2B (or equivalent) bandpass filter with an
overall insertion loss of 1 dB or less to the transmitter R.F. output.

A-6

ANTENNA

DB224 VHF-OMNI 6 DB 360 Degrees Bracket for 2'.-," top mounting. side mounting ava;lable
Size: Length Approx. 20 Ft., Width 1'-- Ft.

Model 5051R/D
RECEIVER/DECODER

GENERAL DESCRIPTION

The Model 5051R/D Receiver Decoder receives transmitted data from field
transmitters or repeate 'r stations, decodes the data and provides an RS232C
output for computer input. The receiver and decoder are separated into two
units so that the receiver can be located near the antenna tower and the decoder
can be located in the central office near the computer. This reduces the amount
of coaxial cable needed, minimizing the signal lost, and increases the strength
of the received signal. The receiver/decoder is supplied with 15 feet of intercon-
necting cable.
The receiver is operated by 12Vdc battery or 11 OVac. A. trickle charger is
included for a 12V battery. To eliminate the loss of data during power outages,
S i e rra- M i sco reco rn m ends t h e u se of a battery for sta n d by power. Th e decod e r
may a Iso be batte ry o perated h owever, wh en a U PS i s i n c I u ded f o r th e com p u ter
it is normally operated by 11 OVac and is backed up by the computer's UPS.
The base station receiver should be used with a high gain omni receive
antenna. This will increase the incoming signal strength for remote sites which
have marginal radio paths.

RECEIVER FEATURES DECODER FEATURES
� Low power consumption * The decoder has tone filters to eliminate noise and interfer-
� Entirely automatic during operation, requires no manual ence from possible adjacent voice channels. This assures
supervision accurate inputs to the computer
� No external controls are available for people to touch and get * Two RS232C output ports standard
the system out of adjustment & 12Vdc battery operated or 11OVac operated

SPECIFICATIONS
Receiver: Duty Cycle: Continuous
VHF Frequency Range: 135-174 Mhz Weight: Encased Unit: 3 pounds
UHF Frequency Range: 400-512 Mhz Size: Encased Unit: 71/4" W x 23/4" H A 9" D
Sensitivity: 0.25 Microvolts Min. (12 dB Sinad) Antenna Input Impedance: 50 ohms
0.35 Microvolts Min. (20 dB Ouieting)
Frequency Stability: +-.001 % (-30 to 60* C) 50501D Decoder:
Channels: 1 Power Required: 11 OVac/6OHz or 12Vdc
Modulation Acceptance: �5.0 KHz Nominal Current Drain: 50 milliairrip's
Power Required: 12VDC, 50ma unsquelched Operating Temperature Range:'-30 to 600 C
25ma squelched Output: 2 channels RS232C with standard RS232C connector
Temperature Range: -40 to 60 degrees C Weight: 3 lbs.

A-7

Model 5073
HYDRALERT SOFTWARE

Software: Available ALERT software comes in two packages: standard and ENHANCED. Both versions have an automated flood
forecast option. Each package is compatible with the U.S. National Weather Service ALERT standards and protocols.
STANDARD HYDRALERT SOFTWARE FEATURES
a data displays automatic data recovery, formatting, and filing
precipitation group summary automatic error checking
single station display 100 sensor storage capacity
e remote user communications (e.g., telephone) 500 data reports stored per sensor
e National Weather Service text file transfer data storage to nearest 1 minute
0 precipitation map environmental data types
automatic hourly map precipitation
map up to 24 hours on-demand water levels
* audio/visual alarm temperature
precipitation wind speed
water level wind direction
* limited line printer output barometric pressure
relative humidity
snow pack water equivalent
analog sensor

Model 5073E.
ENHANCED ALERT SOFTWARE
Enhanced ALERT software contains all the features available International Hydrological Services
in the standard package plus: Enhanced ALERT System

FEATURES UTILITY PROGRAMS
full multi-user and mu'Iti-tasking capability ALARM-GROUP ............. SET ALARM FOR A GROUP
menu-driven operation ALARM-OFF ................ TURN OFF ACTIVE ALARMS
on-line user assistance ALARM-SEE ................. LOOK AT ACTIVE ALARMS
dynamic data storage allocation ALERT ... ***''**'"*'* ........ START ENHANCED ALERT
data base utilities and editing STREAM-SET ................ BASE SET STREAM GAGES
data storqd to nearest second DEF-DBASE ........................ DEFINE DATA BASE
manual data entry DEF-MAP ................. DEFINE PRECIPITATION MAP
event reporting and interrogation capability DEFGROUP .......... DEFINE PRECIPITATION GROUPS
data archiving and retrieval DEFINE-RATING ............... DEFINE RATING CURVES
environmental data types RAW-DATA .................. SINGLE STATION DISPLAY
user specified PRECIP ............... PRECIPITATION GROUP DISPLAY
data displays HYDROGRAPH ....................... HYDROGRAPH PLOT
multiple sensor type groups
MAP-ALPHA ................ DRAW MAP BACKGROUNDS
precipitation group summaries NAMECHNG .................. CHANGE STATION NAME
user selectable date and time interval PMAP .................... DISPLAY PRECIPITATION MAP
user selectable grouping SENSOUT .................... DISPLAY SENSOR NAMES
single station SET-ALARM ...................... SET SENSOR ALARMS
user selectable date and time interval SHUTDOWN ....................... SHUTDOWN ALERT
data plots STAGES ..................... SENSOR GROUP DISPLAY
user selectable date and time interval STGGROUP ................... DEFINE SENSOR GROUPS
rating curves TIMEZONE .................. DEFINE LOCAL TIME ZONE
precipitation maps
up to 10 different map outlines
user selectable time and date interval
text labeling of station names
action/response displays
external control capability
terminals map displays, optional
alarms beeper systems, optional
audio/visual alarm
all data types can be alarmed
complete line-printer output

A-8

Model 5071 UPS
UN, INTERRUPTIBLE POWER SUPPLY

GENERAL DESCRIPTION

The5071UPS is usedto keep the computer operational during powerfailures
and to protect the computer from low voltage "brown outs," lightning or other
types of transient voltages and AC line noise.
Since even a 16 millisecond loss of power can cause the computer to drop out
of operation and need rebooting, Sierra-Misco considers the UPS essential for
the trouble tree operation of the central station.
Operation is simple. AC power is converted to DC power and is used totrickle
charge low maintenance 12volt batteries. The batteries in turn supply power to
an inverter circuit which creates AC voltage for the computer and decoder.
There is no loss in synchronization, no loss in phase, and no loss in output
voltage during an outage or return to AC power. rs
The 5071 UPS incorporates a two-stage precision battery charge system that recharges the battery system within 6 to a hou
after use. Once the batteries have reached 95% full charge, the two stage charge system switches to float operation.
When used with one 5071UPS-B Battery the UPS will operate a 5071 Central Site Display continuously for approximately 20
minutes. More batteries can be installed to allow for longer power failures. If extended power failures are anticipated a motor
generator set should be used in addition to the UPS.
A battery cable and battery are supplied with the UPS.

SPECIFICATIONS

Model 5071UPS (60 Hz) Model 5071UPS-2 (60 Hz)
5071UPS-1 (50 Hz) 5071 UPS-3 (50 Hz)

Power Out 300 600
Power In 110/220 110/220
Operating Time with 1 Battery 20 minutes 20 minutes
Operating Life of Battery Approx. 5 years Approx. 5 years
Noise Attenuation >90 db >90 db
Regulation 95 to 130 VRMS 95 to 130 VRMS
Size 22" x 17" x 10" 22" x 17" x 10"
Weight 80 lbs. 150 lbs.

MICROCOMPUTER

The base station microcomputer is an IBM PC/XT configured, with 512 K of
memory, one 360 K 5 1/4" floopy disk drive, and a 10 MB hard disk drive.

OPERATING SYSTEM

The Enhanced ALERT software works under the QNX multi-user, multi-tasking
operating system.

APPENDIX B: STORM SURGE AND WAVE MODELS

B.1 STORM S]U&GF, MODFLS

Introduction

Theoretical models of storm surges all involve some degree of approximation
and often questionable assumptions of the actual physics involved. The first
theoretical models of storm surge were analytical, calculating storm surge
along straight continental shelves with parallel.. contours and constant wind
stress. To solve these equations, bottom stress terms had to be linearized,
and other aspects of the physics were only approximate. In general, these
analytical techniques provide a useful basis for understanding some of the
physics of storm surges, but lack the full physics governing the process required
for accurate predictions.

An alternative approach to storm surge modeling arose once computer time
became more readily availablet and numerical techniques, acquired more widespread
popularity. In the past fifteen years, ever-increasing numbers of numerical
models have been developed which can address storm surge problems. Many of
these models are similar, @ differing only in representation .-of some of the
terms in the equations of motion, or in the precise -detail of the numerical
implementation of a term (a good example being the variety of ways to implement
the nonlinear inertial terms). Many of these models differ in a more fundamental
fashion, however, in that they represent different physics.

As an example, bottom stress -- the resistence of the rough ocean bottom
to propagation of -any surface disturbance -- can be'approximated in many ways.
One approximation invokes a higher order turbulence closure scheme to approximate
the effects of bottom friction. This yields adequate results in many cases,
but also increases computational time and requires more assigned parameters.
A simpler approach is to incorporate a linear bottom friction model, where
the friction coefficient is dimensional because of the linearity in velocity.

More complex, but largely empirical in derivation, is a quadratic friction
term 9 where the friction coefficient describing the coupling between the flow
and the bottom is a more appealing nondimefisional number. These techniques
generally ignore flows at different time scales. -For instance, a storm surge
model will ignore flows at much higher or lower frequencies. Although tides
may be incorporated in these models, the effects of surface gravity waves
(wind waves) and other disturbances generally are not included. Recent theory
has shown that higher frequency flows increase the bottom friction associated
with longer. period motions such as tides and storm surges, so future storm
surge models will have to improve the physics of this term.

The above example illustrates the magnitude of the uncertainty in developing
and applying a storm surge model. Computer methods have increased our abilities
to consider more realistic physical cases, but there are still theoretical
uncertainties as to what constitutes a realistic physical case. The importance
of differences in model details are vigorously debated among scientists and

engineers developing these models. The bottomline is that there is no single
model which will best fulfill the job of accurately predicting storm surge.
A model which performs well at one site may not perform well at another, because
of improper physics. For instance, a model with a poor bottom friction represeir-
tation may perform well in a deeper embayment, but do a much poorer job in
Long Island Sound,, which is much shallower. The best model for a particular
area may also be too expensive to run for the variety of cases required for
compilation of an atlas of storm surge scenarios, for instance.

Following is a brief overview and description of the two major techniques
for estimating storm surges, and how they have been. and may be applied to
the Connecticut coast.

B.1.2 Statistical Storm Surge StudieS

Many of the estimates of storm surge height are derived from historical
data concerning past storm surges. To interpret these past results and to
apply them to forecast 'future anticipated storm surges, the observations must
be placed into some statistical framework. This statistical framework is fraught
with uncertainties and assumptions, but can be applied in a climatological
sense to provide estimates of expected surges. This method, however, cannot
provide estimates of expected surge during a particular storm, a shortcoming
making them of limited utility for this study.
Where possible, tide gage data are used to generate statistics of *storm
surges (46, 187) in concert with non-gaged estimates of surge level during
large hurricanes and storms. These observations are then fit to a statis-
tical distribution of storm surges and superelevation. Boon et al. . (187)
use a Poisson distribution, others use a. Weibel distribution, while Dewberry
and Davis (46) use a Pearson Type III distribution. There is considerable
debate about the proper type of distribution to use; if the forecast is. for
a 100-year frequency or greater,, the results may not be too sensitive to.' the
distribution. However, 500-year events are particularly susceptible to differences
in distribution. selected.

Another common problem in using statistics of extreme events to forecast
flood levels As the occurrence of outliers. Outliers are generally extreme
events which significantly degrade the fit of the data to a statistical distri-
bution, compared to all other data. These outliers commonly are larger events,
which should influence the forecast. There is no standard technique for treating
outliers, but it is not uncommon to leave these out if the other data fit
the statistical model without it. Although not uncommon in practice, it might
be better to suggest a different model than to eliminate data because of lack
of f it.

Most statistical storm surge models neglect changes in relative sea levels.
Since relative sea levels are. indeed increasing along the Connecticut coast
this should be considered in longer-term estimates of storm surge. It will
have no significant effect on storm surge estimates for time periods shorter
than 20 years or so.

B-3

STATISTICAL STORM SURGE STUDITN

There have. been three major studies of statistics of storm surges along
the Long Island coast of Connecticut. The first, in 1973, was published by
the New England Division of the U.S. Army Corps of Engineers (COE) (89). Those
study results were revised in 1980 during the second study by the COE (6)
using tide-gage data from five stations (Willets'Pont, NY; Stamford, Bridgeport,
New London, and Stonington, Connecticut). A major decision in the 1980 study
was to eliminate the 1938 hurricane from the statistical model, thereby lowering
the 100-year flood estimates, particularly in eastern Connecticut. Tidal
flood profiles from this study are shown in Figure B.1.

In 1982 Dewberry and Davis (D&D) performed the final study for the Federal
Emergency Management Agency (FEMA) (46), which was essentially a review of
the 1980 COE study. The major difference resulted in D&D's inclusion of the
1938 hurricane in their statistical model fit, particularly in eastern Connecticut
where the 1938 surge was highest. D&D recommended the adoption of the COE
1980 surge profiles, except in the New London area where an increase was suggested
to fit the 1938 hurricane data. The resulting profile (Figure B.2) was adopted
by FEMA for updates to its coastal flood insurance studies.

The latest 100-year flood profile shows the highest flood level in western
Connecticut (12.2 feet NGVD), lowering to' 10 feet by Stratford. From Stratford
east the level rises to about 10.7 feet at East Haven, followed by a gradual
decrease to about 10.0 feet at Waterford. At New London the level is 10.0
feet NGVD. To the east of New London- the flood increases from about 10.0
feet to 10.8 feet at Stonington.

These flood profiles show that storm surge increases dramatically within
the Thames River estuary. According to the COE 1980 study, storm surge increased
-from 9 5 feet to 14.3 feet NGVD , at the 100-year level as the distance from
the mQtb of the Thames River. increased. The 1938 hurricane surge ranged
from 9.8 feet -at New London up to 15.2 feet in Norwich. This estuarine effect
may not be modeled adequately by. the numerical approximations, so care should
be taken to assure that this increase in height in embayments is. known to.
flood management personnel.

NWS STORM SURGE MQDFL FOR FXTRATROPICAL STORMS
The NWS has adopted .a storm- surge model for extra-tropical storms (73)
which is a statistical storm. surge model (or empirical, in,.NWS's terminology).
Using simple, regression methods, the observations of storm surge at ten coastal
locations. (with tide gages) are related to sea level pressure values as forecast
by the National Meteorlogical Center (NMC). Using.68 storms occuring from
1956 through 1969, regression equations were established using a screening
procedure,. to allow the best fit between observed surge and sealevel pressure,
at a minimum number of stations to reduce artificial predictability and increase
forecast skill.

The procedure is entirely empirical, and is based on the observed and theorized
relationship between atmospheric pressure and storm surge. The errors in
this empirical technique can be very large, although it does a reasonable
job forecasting during some storms. These regression equations apparently
have not been updated since 1974, and there are no present plans to do so (71).

ELEVATION IN FEET ABOVE 94 0 V D

00 0
ji

0 FF

ow OD

C: F-

cr 0
f< 0
1-7 - - -----
0 0
er 0 0
o p- I QM'S

0.
ii;"Mm
t-h
C z
c

ID
An

r- A

9 T.
i MATC" LIOEI ILE 2 -

oz ELEVATION 10 FEET ABOVE N 6 V 0

0
ELEVATION IN FEET AGOVE N 0 v 0
..T LINE P.J.L.
STA.

CLI

z
z

r1l a
+

iot] 21

I MATCH LINE PROFILE 3 It I

ELEVATION IN FEET AOOVIE NO V 0

z
T F

ELEVATION 114 FEIET ASOVE N0 V0
L, @.E PROFILE 2
A.
UP al.-,
T- T

tv@l

Irt, a

_F_F
JJMATC" LINE I I P"OFjLl 4
f

ELEVATION In FEET A9OVf NO V D

9-9

0
ELEVATION IN -FEET ABOVE IF 6 V 0

MATC IKE PROF ILE 3
STC .-"i

C',

cli ic
m

I... v. ;E

;i o Z

C:
Ar
MA,
14
0
rt

r
rl ELEVATION IN FEET ABOVE N G V 0 >
z

CORPS OF ENGINEERS
NEW LONOON WATIRFORO MONTVILLE NORWICH
GROTON
L.10YARI, I PRESTON NORWICH-

ARID PMR T MAN

'.3
AM! FICAff Of JfP 21. 1956 MAE A 000
>

1150 YEAR Y TIVAL PLOOD
NUMCA&Z XM A Me md1
YEAR r r110AL 000

A. ...... ... 1.

#,ON #,-,m nor",

A
;19
NOTES

. ....... .. .........
-10*Al WOM11C @IW I L
"T.
$1. L.V.1 C
I I I I A, .. 1-1 .. - TIDAL
Vw w"

A 7 12 13 1.
DISIA"Cl IN STATUTE MILES fROM MOUTH OF THAM@S RIVER AT EASTERN POINT

FIGURE B.l: Tide Levels and Flood Profiles for Connecticut (Cont'd)

W
40 44

4 4
:'4
-.4

Libil
"A 21 M!,
4 444

4:-

a. :,,,I
17-
4
,4
-4 q. I.;
...... ......

77: 1.. ....

...........
. ........ ....

..... ........ .........
............... .....

. . .. ........

12
-H
:.:7

...... ......
........ .......

.... .........
... .......
........ .....
77.7-7
......... ....

....... 4- LEGEND
... .........
7
SOURCE: Dewberry Davis. 1982. Tidal Flood Profiles for the Connecticut 5W YEAR rL000
Shoreline of Long Island Sound. Prepared for the, Pederal Emergency 100 YEAR FLC'30
Kanagement Agency.
50 YEAR FLOOD,
000
.................... - - - - - - 10 YEAR FL

0 5 10 Is 20 n M 35 Mj 45 50 Go
51. Aiu-rr MILLS - LONG ISLAND SOUND
@ 4M-,

......... .

PIGURE B.2: Flood Profiles for Connecticut

ELEVATION IN FEET ABOVE "GVb

�L

t2l

tzp
ff t
I All
1 14
Aq-

It
A4
If

cli ------
It m II - ----
4

JL
itil, f -4
1-h
I
:j
I I It
I ALL'-
0

--4
to
I+

0 --------

LIN T 1::_

11 it
L L@ L-L
+ 71�
-14----
m m

FEDERAL EMERGE11MY MANAGEMENT A"Ncv
TIDAL FLOOD PROFILES.
NEW ENGLAND COASTLINE
LONG ISLAND SOUND & BLOCK ISLAND SOUND
T
4 4-4
I
Ittl
L L-Lill

01-9

For most of the ten stations, two regression equations were- developed.
One, utilizing sea level pressure at several locations, is used on the NMC
computers to generate a storm surge forecast that is provided to local National
Weather Service offices. A second equation, utilizing sea level pressure
from fewer locations, can be solved manually by local weather service offices
o forecast storm surge.

Stamford, Connecticut is one of the ten locations for which regression
equations were developed. Only five sea level pressure stations are used
in the Stamford equation (as opposed to 7 - 15 stations for most locations),
and the same equation is used by both NMC. and local weather service offices.
The equation, used for Stamford is shown-at Figure B.3.

SS(SFD) 24.061+ .06265 P(12)t - .07930 P(31)t .03170 P(40)t
+ .05521 P(18)Zt - .02926 P(27)t

SS = Storm Surge (in feet)
P = Sea Level Pressure (in millibars)
(12) Grid Point f or Sea Level Pressure
t Time of Sea Level Pressure Observation

FIGURE B.3: Regression Equation for Extratropical Storm Surge Forecast,
Stamford, Connecticut

Figure 4.1 illustrates the forecast vs. observed storm surge at Stamford
for two storms in 1972, and indicates that the model consistently over-estimates
storm surge at Stamford. The COE, which uses NWS storm surge forecasts as
an aid in operating the Stamford Hurricane Barrier, also reported that forecast
surges are usually higher than recorded surges (25,39).

If the State of Connecticut were to incorpora.te this type of extratropical
storm surge forecast into a coastal flood warning system, several improvements
to the current procedure are suggested. First, the regression equations should
be developed for additional locations having storm surge records (Bridgeport,
New London, Old Saybrook). Second, the equations should include additional
sea level pressure stations which should be carefully chosen based on there
predective capability as indicated by historical records for many recent storms.
This improvement in the methodology of regression is needed to assure robust
estimates, and minimize problems of artificial predictability.

The utility of these statistical techniques is limited, however It is
recommended that this methodology be replaced by dynamic models of storm surge,
even for extratropical storms.

B-12

ILL3. Numerical Storm Surge Models

To predict the storm surge associated with a storm of arbitrary features
(such as path, wind speed, size), the statistical storm surge summaries are
inadequate. Necessary in this situation is a realistic model of the effects
of winds on the surface of the water, including all physics appropriate for
the ocean basin of concern. Generally the model uses as input some representation
of the storm, including its path, wind distribution, and speed.

For the case of hurricanes, such models have long been in existence. The
first such model, developed by Wilson in 1957 (188), includes the parameters
of central pressure index, the distance from the hurricane center to the point
of maximum. winds, and the forward velocity of the hurricane. Subsequent repre-
sentations of hurricanes include a more realistic description, increasing
realism while also increasing computational time.

Models for extra-tropical storms are much more difficult to generalize,
and are derived most often from synoptic weather charts, updated every four-
to-six hours.

MODFL TYPIE AND PARAMEJERS

The number of numerical models which have been applied to storm surge problems
is very large, increasing rapidly each year. More than 30 such models were
reviewed as part of this study. The different types of models and some of
the important parameters used in such models are reviewed briefly in the following
pages. Although not exhaustive, this discussion provides some understanding
of the difficulties in representing the physics of the ocean in a numerical
format, and illustrates some of the pitfalls to be avoided.

For further review of the state-of-the-art in storm surge prediction, several
references are available. Marine Forecasting by Niboul (189) provides a useful
review of the concepts of storm surge modeling, current to the date of publication.
Pagenkopf and Pearce (190) provide a detailed discussion of several types
of storm surge models, their differences, and their performance in predicting
surges during a hurricane. Many similar publications exist, from an introductory
level up to the most current.

Numerical storm surge models use the basic hydrodynamic equations governing
fluid flow as a starting point. The appropriate equations are the Navier-Stokes
equations for fluid momentum, and the continuity equation. The diff erences
are in the way these equations are implemented numerically, which terms are
included, how the terms are included, and the application of the solution
of these terms to a physical problem.

Some of the important classes of. solution are discussed here. Basically,
the storm surge models include inertial effects, incorporating the unsteady
term in the equations of motion; the convective term; and a Coriolis acceleration.
Theotber terms in the equations are the pressure gradient term and the diss-
ipation term. Besides diff erences .in numerical implementation and gridding
of the equations, the parameterization of the dissipation term is one of the
largest diff erences between various models.

B- 13

One of the most fundamental differences between models is the numerical
scheme implemented. Two methods for approximating the equations of motion
numerically are finite difference and finite element techniques. Finite element
techniques have only recently (since early 19701s) become popular in ocean
.hydrodynamics, while finite difference techniques have been around a long
time. . Pakenkopf and Pearce (190) provide a quantitative comparison between
,these two techniques, using a modified finite difference model of Pearce (191)
and finite element model of Connor and Wang (192) and Wang and Connor (193).
The finite element model is generally considered to be more appealing because
of its flexible grid,- where grid elements need not be of constant size. The
finite element implementation is normally considered to be more expensive
to run (194) although this is disputed by (190,195). Finite elements also
have different stability constraints than finite difference, allowing larger
time steps for',a given level of numerical stability.

Finite difference techniques are still the most widely used in spite of
the advantages of the finite element models. The higher cost of the finite
element technique has made many investigators shy away -from it. Although
for a long-time-simulation the finite element scheme may be cheaper, it is
normally much more expensive for shorter simulations. The finite difference
method is also the most widely taught in engineering schools.

To get around the problem of rectangular grids required by finite difference
models, several interesting schemes have been proposed and implemented. First,
a boundary-fitted coordinate system has been suggested such that in a transformed
coordinate system the grid is rectangular' - but in the norr-transformed coordinate
system the grid is not regular. This allows the models to be adapted for
specific geometries of shorelines. Examples of this technique are Johnson
(196), Thomson et al. (197), and Spaulding (101).

Another solution has been to develop -a metho Idology for irregular grids
in finite difference techniques. An important series of articles on this
technique have been produced by Thacker (197, 1918, 199). In this methodology,
an irregular grid is produced to conform to the boundaries of the problem,
and the appropriate numerical transformations applied to it. Although this
technique has provided some interesting results, there is still a question
about stability @ of the method (195), and, arguments about why it may be more
appropriate than alternative techniques. Finally, a variety of other grids
have beew applied, such as curvilinear grids and stretched rectangular grids.
These all must be applied with care, to avoid or minimize stability problems,
and are generally difficult to achieve maximum resolution in those areas where
itis needed most.

Since computational time and resultant expense increases as the size of
the computational grid element decreases, there is considerable work on reducing
the size of the grid to an acceptable level, and living with the degree of
accuracy resulting (finite element grids do not have this limitation). The
smaller the grid size the smaller the, time step required to achieve stability;
hence the trend (discussed above) towards achieving finite difference grids
having variable resolution. One way of getting around the limitations of
the finite d'ifference restrictions is to run two grids,' in a nested sense.
A coarse grid is run to cover the offshore conditions, where the fine resolution
is not needed, while a finer mesh grid' is run inshore, where resolution is
essential. This is an acceptable compromise for modeling areas with variable

B-14

resolution requirements using finite difference techniques. It has been used
-in Long Island Sound, for instance, by Gordon and Spaulding (99) and Spaulding
and Gordon (100) to calculate the tides.

Besides the numerical implementation of the equations of motion, and the
problem of gridding the geographic area to obtain adequate resolution at a
reasonable cost, there is a consideration of the dimensions of the equations
to be calculated. The simplest models are one-dimensional, which the analytic
solutions tended towards. The next step is two-dimensional, the most common
being a vertically-integrated model with the vertical dynamics ignored. The
two horizontal coordinates, x- and r, then express the momentum balances
in the flow. Finally, there is a class of three-dimensional models, which
are required to specify flows when the vertical dynamics are important. Generally
as the number of dimensions increases, the cost of the analysis increases.
Many examples of these different models exist, and are not detailed here.
Most storm surge models are vert ically- averaged two dimensional models, since
the vertical, dynamics are not particularly important in describing storm surge
processes. Although this is an assumption placing a constraint on the accuracy
of the model, it is not an unreasonable assumption.

Other differences between models include the parameterization of bottom
friction and other dissipation processes. Many models use a quadratic bottom
friction, where the dissipation is proportional to, the square of the near-bed
velocity. Commonly, a Chezy-type friction is applied, or a Manning formulation.
These ignore the effects of the bed geometry and the surface wind waves on
the bottom friction, a step which is reasonable in deep water but' not acceptable
in shallow water. As Grant and Madsen (200, 201), have shown, in shallow water
where waves are important, these higher frequency motions increase the'drag
felt by any longer period motions across the bottom. Incorporation of the
effects of the non-linear interaction between waves and currents is required
if dynamics of shallow water flows are to be described accurately. Few numerical
models incorporate this bottom friction due to wave-current interaction, but
for Long Island Sound such a physical model should be included for accurate
storm surge prediction.

Another matter of critical concern in numerical modeling is the prescription
of boundary conditions. Boundary conditions have a direct. impact on the storm
surge calculations, and must be analyzed critically. For, instance, at the
coastal boundary, several types of boundary conditions are possible. First,
there can be zero velocity normal to the boundary, a condition which is reasonable
if the coastline is a high, steep cliff. This is a common boundary condition.
However, in the case of a low-lying shoreline, where wetting will occur, this
is an inappropriate boundary condition. In this case, more realistic boundary
conditions must be applied, with a knowledge of bow flooding occurs. This
entails the use of a boundary condition applied along a moving boundary, a
modeling problem which has been solved before. . This moving boundary requires
fine resolution, again requiring a nested grid to allow computations to proceed
at a reasonable cost.

On the open boundary which terminates the model to seaward and laterally,
a similar dilemma arises. An open boundary will have several possible conditions
applied to it. Physically, one requires a description of the physics outside
of the region, to match with the physics derived for the interior with the
model. This is not generally known. To minimize these open boundary problems,.

B- 15

one generally applies open boundary conditions far from the coastal region
of interest, and applies a condition which is not unreasonable physically.
The sensitivity of the surge calculation to different open boundary conditions
can be determined numerically; if the model is extremely sensitive over the
time duration of the simulation, a more complicated open boundary condition
may be applied.

The simplest open boundary condition is that there is a continuity in sea
surface across the boundary, and that there is no flux parallel to the boundary.
As emphasized by Reid (202), this condition corresponds to complete reflection
of gravity waves. If this reflection is not large, or the time interval sufficr-
iently small, this may not be a restrictive case. When the surge behaves
like a f ree Wave, a radiation condition must be applied to minimize the effects
of the reflectivity of the open boundaries (203).

CONSIDERATIQNS FOR A LI

This brief overview of the modeling problems associated with implementing
the equations governing storm surge illustrates the variety of uncertainties
and problems associated with these models. With the debate within the scientific
and engineering community sti 11 showing no 'signs of abating, there is no clear
consensus on which model to use for what situation. There are some clear
trends, however.

1) A two-dimensional numerical model, is appropriate for storm-surge calcula-
tions* If the 2-D model uses finite difference techniques, a nested grid
must be used. If the' 2-D - model is finite element, then a single grid could
be used.

2) The open boundary conditions must be implemented carefully. On the
open boundaries, a radiation condition may be required for certain storm paths.
Since there is only a single open. boundary in the Long Island Sound 'case,
this implementation should not be 'difficult. If a radiation condition is
not used, numerical experiments must be run to show that the model is not
excessively sensitive to the type of open boundary condition selected.

3) The shore boundary conditions should reflect the possibility of land
wetting for the low-lying areas *of the Connecticut and Long Island shores,
paying particular attention to the estuaries, of Connecticut. With the large
storm surge in the Thames River, for instance, due consideration must be paid
to their effect on storm surge downstream. Again, numerical simulations should
be required to demonstrate the sensitivity of the model to the boundary conditions
selected.

4) Any model will require input of meteorological condition's to run the
model. Some models will 'work off atmospheric pr ,essure input, others need
calcuated winds. Some models require speed of movement of the storm, others
will interpolate from synoptic weather charts. For tropical cyclones, most
models incorporate a simple model of winds within a cyclone,@ requiring only
parametric input such as central pressure anomaly, some length parameters
relating to winds, and speed of propagation. Preferable by far is a model
which accepts atmospheric pressure input, and calculates the. surface wind
stress field from that. A comprehensive storm model may not apply to all
types of coastal storms, but should be emphasized in future research on progress

B-16

in storm surge modeling.

5) Shallow water processes should be -represented well in any model of
Long Island Sound. Bathymetry must be input with as -much resolution as possible,,
and incorporation of nonlinear bottom stress due to wave/current interaction
should be made if possible.
6) Because of the effects of tides on storm surge,, the numerical model'
should combine a tidal model with a pure storm surge model. This way total
water elevations can be predicted, not just the storm surge component. If
this model is run in real-time, such a tidal inclusion is straight-forward,
and is routinely performed. If the model is run in a. forecast mode with an
eye towards generating an "atlas" of storm surge scenarios, then the tide
must be added in after the model is run.

NUMERICAL STORM SURGE MODEJS TISED IN LONG ISLAND SOUN

Several numerical storm surge models, o r portions of larger models, which
have been used in Long Island Sound are briefly reviewed below.

Laevastu and Callaway (204) bad a 2-D finite difference model of Long Island
Sound as part of a larger model. This model had a grid spacing of 6.6 km.
The grid is so coarse as to be of little value in the prediction of local
storm surges.

Leendertse and Liu (205) applied a 3-D numerical finite difference mode I
to Long Island Sound, using a horizontal grid spacing of 1.9 km. These were
of short duration (order of a single tidal cycle), the primary intent being
to estimate turbulent energy fluxes in the region.

Beauchamp and Spaulding. (206) developed a tidal model of Long Island Sound
as part of the New England Bight, using a 2-D finite difference model with
1.852 km grid spacing. With limited observations available against which
to compare the model, the work could not be evaluated, completely.

Murphy (207) applied the same 2-D finite difference model to a small area
within Long Island Sound. The results are not particularly applicable to
the present study.

Two models will be discussed in a little more detail: one by Spaulding
and Gordon (100), and the SLOSH hurricane model by NW8 (93, 94)

Spaulding -- Spaulding and his associates have extensive experience in
modeling-the waters of southern New England. Papers by Gordon and Spaulding
(99) and Spaulding and Gordon (100) discuss the application of a nested numerical
tidal model to the southern New England waters, including Long Island Sound.
Although primarily a tidal 'mode 1, it can be adapted easily to include storm
surge effects. The model is a 2-dimensional, vertically integrated finite
difference 'implementation of the equations of motion. , It has ignored the
convective acceleration terms, and employs a Chezy-type bottom friction formula-
tion. It ignores the wave-current interactions and their effect . on bottom
friction. The larger grid interval was 5 55. km' while the smaller grid interval
was 1.852 km. The model appeared to work well on tidal time scales associated
with this study.

B- 17

Since storm surge effects were not included, there was no wind stress term,
and' the time history of development of a wind field could not be included.
In a later paper (101), wind stress (or surface stress) was included in the
formulation using boundary fitted coordinates, and,applied to the North Sea.
Any future application of the Spaulding-type models must include a storm model
for generating vector wind fields. Such a model is not described in the literature
in connection with the tide models cited above.

NWS SLOSH Model SLOSH (Sea, Lake, and Overland Surges from Hurricanes)
is a numerical tropical storm surge model developed for real-time forecasting
of 'hurricane storm surge along the continental shelves. It was adapted from
an earlier model used by NWS, SPLASH (Special Program to List Amplitudes of
Surges from Hurricanes). It is a two-dimensional, finite difference numerical
model with a curvilinear, polar coordinate grid (Figures B.4. and B.5) to
increase near-field resolution, while sacrificing far-field resolution. The
model includes a storm wind model, which is fed by several time-dependent
meteorological storm variables:

1) Latitude and longitude of storm- positions at 6-hour intervals for a
72-hour storm track. This begins 48 hours.before the storm's nearest approach,
and ends 24 hours after the nearest approach.

2) Storm central pressure at 6-hour intervals.

3) Storm size (center to region of maximum winds) at 6-hour intervals.

Wind stress vector fields are computed independently by the model, and
are not input parameters. The initial height of the still-water surface before
the storm is required. Far-field boundary conditions are 'computed far from
the region of forecast interest to minimize their effects on the simulation.
All geographical' and bathymetric -data must be input by the user, continually
updating it in the case of real-time simulations to assure proper boundary
perf ormance.

The SLOSH model makes several approximationsi First, it does not include.
the advective terms from the equations of motion, since they have been shown
to be small except in regions of large'velocity gradients. Second, it incorporates
a time-history bottom stress, formulation (208), which does not incorporate
Chezy-type friction coefficients, nor wave-current interactions. NWS acknowledges
that the wave/current interactions are important on shallow shelves, but not
on those of intermediate depth. Since Long Island Sound is a shallow shelf,
bottom friction due to nonlinear wave/current interaction should be included.
Other wind-wave effects such as run-up and set-up are not treated. explicitly.
They are treated implicitly in their use of bottom stress terms and other
terms which are derived empirically from a historical data base. These wave
,terms act as noise sources, and their effects are included although not in
a physical manner.

The SLOSH formulation does not include a tide model within it. The reason
for this is the uncertainty in timing of tropical cyclones with respe Ict to
the surface tide. The second reason is that the SLOSH model is also used
in a forecast, . or - "atlas" mode, where the storm surge is simply added to the
corresponding tide. The error in not including the tidal -calculation arises
in the finite amplitude terms, where the surface tide@may raise or lower the

B-18

kGANSETT AND BUZZARDS SAYS

SLOSH BASIN

V"w

Source: Techniques Development Laboratory, National
Weather Service, Silver Spring, MD.

FIGURE B.4: Polar Coordinate for Narragansett and Buzzards Bays
SLOSH Basin

B- 19

76*W 741W 72'W 70*W
44'N 44*N

NEW YORK/

LONG ISLAND SOUND

SLOSH BASIN

4M 42*N

40*N
40ON

38*N 38*N

70*w 74*W 7L"W 706W

Source: Techniques Development Laboratory, National
weather Service, Silver Spring,'MD.

FIGURE B.5: Polar Coordinate for New York/Long Isl and
Sound SLOSH,Basin

B-20

datum on which the storm surge acts. This should not be a major drawback
-in the Connecticut, coastal area where tides are relatively low.

In application to the Connecticut coast, the SLOSH model has some problems
inherent in it. Because of the shallow nature of Long Island Sound, the bottom
friction formulation used in SLOSH will not correctly predict dissipation.
Future improvements to SLOSH could include better representation of the physics
of the bottom boundary layer, which could be done with no large increase in
run costs.

If the SLOSH results do become available for the Connecticut coast as they
should in the near future, careful comparison with observed storm surge should
be carried out, and the source of any discrepancies identified. Bottom friction
is one source which could be poorly represented by SLOSH, but locally advective
effects could be important (they are ignored by SLOSH).

Another major concern in the Connecticut coast is the effect of Long Island
on tropical cyclone passage. As seen in the 1976 Hurricane Bell and 1985
Hurricane Gloria, Long Island appears to have a major effect on the wind field
of hurricanes. If the forecast winds were much larger than actual winds,
hurricane surge would be overpredicted, with consequent increased expenses
associated with evacuation. This emphasizes the need for evaluation of the
model locally, where the wind field around a hurricane becomes extremely complex.
The 1938 hurricane and the 1985 Gloria would be useful examples against which
to compare the wind stress, model and resulting storm surges.

The polar grid must be implemented carefully along Long Island Sound to
assure a uniform grid. Large alongshore differences in grid spacing would
result in greater uncertainties in storm surge simulation in some areas than
others. The State should consult with NWS when model simulations are run.

WAVE FORECASTING/BTNlDCASTING MQDYJA

Introduction

Wave forecasting and hindcasting are accomplished by approximating the
physics of wave generation and wave transformation by parametric or numerical
methods. Although these. techniques date back quite a few years, the earliest
publication in, book form of which is Sverdrup and Munk (209), recent advances
in these techniques make them more reliable and accurate. Since these techniques
are only approximate, they don't reproduce exactly the correct physics behind
wave generation and transformation. Some of the techniques are more appropriate
for deep water uses (such as the Navy's Fleet Numerical Weather Central wave
model), while others do a much better job approximating physics of shallow
water waves. Some require elaborate computers for calculation, and long compu-
tation times, while others require only limited computation, being accomplished
mainly by nomographs. Almost all methods use the synoptic wind field as input
for calculations. Since the fine details of the synoptic wind field are not
available, local variability in waves often is underestimated by these models.

B-21

B.2.2 Wave Model 3:ypes and Parameters

In general, wave models can be considered discrete or parametric. The
discrete.models attempt to simulate the wave energy balance or transport equation
directly, with all of the wave generation (source) terms and the 'wave dissipation
(sink) terms. These models, dating back to Pierson et al. (210), have advanced
considerably over the past twenty years. They must all use some parameter-
ization or representation of the various source and sink terms to provide
adequate results. In contrast, a class of models known as parametric wave
models have evolved from the initial work of Sverdrup and Munk, (209), in which
the major features of a wave are derived more simply (represented in nomograph
form by S-M), reducing computational cost. All rely to some degree on empiricism,
relating wave characteristics to the forcing terms (wind).

As might be pr edicted, these two approaches have led to hybrid models,
where elements of discrete models ar 'e combined with elements of the parametric
models. This hybrid approach can be used to describe different elements of
the wave field, or the wave field at different stages of development. There
is considerable, ongoing debate over which of these two (or three) types of
models is most appropriate for shallow water conditions.

The COE for instance, historically has used a parametric approach, as described
in the Shore Protection Manual. Recently, however, they have been developing
a discrete wave model for use in shallow water. Its performance has not yet
been tested completely with- field data. In contrast, much recent work has
gone into improving pa rametric wave models. Several oil companies are now.
providing an intercomparison of the models to try to evaluate the performance
of the different models. The results of an experiment in the early 1980's
(211) showed that the differences between model results 'are large, and not
explainable by uncertainties in meteorlogical conditions. The debate will
continue as the proponents of. the different models continue their theoretical
development and comparison with field data (which are extremely sparse).

For the Long Island Sound case, a model should be selected*which will account
for finite depth effects, and not rely on deepwater relationships. Such models
exist in both a discrete and parametric form. Very' important in the finite
depth case is a proper representation of the bottom friction term, as Well
as other sources and sinks'. Given the variety of different models available,
the fact that they all yield 'results distinct from one another, and the fact
that there has been no definitive intercomparison because of lack of a good
data set, there is considerable latitude in selection of an appropriate wave
forecasting model.

B= NWS Wave Forecast Model

The National Weather Service uses a wind-wave forecast f or generalized
offshore wave conditions. This wave forecast is of the parametric type, based
largely on empirical relationships between the size of waves generated by
specific winds. It follows in the mold of the Sverdrup- Munk- Bretschneider
(SMB) type methodology first developed in 1947. Three parameters required
to use these nomographs are wind soeedg fetch length, and wind duration.
Each of these is discussed briefly below.

B-22

Wind speed suffers from need to specify average wind speed over the fetch
.of the storm and over the duration during which it existed. This specif i-
cation is a primary weakness of the limited nomograpbs, since, the precise
details of the averaging can affect the final result. The wind' speed has
to be adjusted for atmspberic boundary layer effects; thus wind cannot be
input simply from. calculated geostrophic (or thermal) winds generated from
synoptic pressure charts. Details of this correction are generally ignored
in most parametric forecasts of this type.

Fetch is the distance over which the "constant" wind has been ',blowing.
For an easterly wind in Long Island Sound, for instance, the fetch is much
smaller in eastern Connecticut than in western Connecticut. The definition
of the fetch is determined by some subjective decisions about the size of
the pressure system causing the winds, and other such matters. The definition
of fetch therefore is far from exact.

The final term needed to apply these nomograms is the duration of the wind.
This must be the representative time during which the wind speed has acted
over theprescribed fetch. Clearly these three parameters must be chosen
carefully to make this simple forecast of wave conditions.

For the NWS purposes of providing marine forecasts for mariners, genera-
lized wave forecasts may be adequate. However, since these simple nomograph
techniques ignore all details of wave scattering and dissipation, they are
not applicable to forecasting wind waves for coastal localities. Examples
of the major areas of omission in the nomograpbs include: no bottom friction '
no wave refraction, no wave reflection, no wave diffraction, lack of inclusion
of a time-variable wind field and fetch length. Again, these- omissions may
not affect the generalized wave forecasting needs of NWS, but they are critical
to the mission of accurately forecasting coastal wave fields.

For purposes of providing coastal flood warning to the reside nts of a coastal
reach, the NWS methodology is clearly inadequate. For best results, a numerical
wave forecast model is required, which includes the full effects of dissipation
and scattering.

Elements of a LIS Wave Model

The important elements of a wave model to be consid ered for LIS include:

Shallow water form
Appropriate form of bottom friction to account for nonlinear losses
Inclusion of wave refraction/diffraction for shallow water.
Proven performance and reliability
Reasonable performance in standard intercom pariso ns
Reasonable cost and efficiency
Appropriate and separate treatment of both locally-generated and swell-
components.
Some spectral form to properly account for wave-wave interactions.

Based on a survey of the field 'and opinions of other oceanographers in
the field, one excellent choice for providing LIS wave forecasts is the hybrid
wind-wave model of Graber (105).

B-23

In this hybrid model, Graber uses the shallow water form of the wave equations,
applying the most advanced -friction estimates to correct for finite depth
effects, and incorporates refraction and shoaling. This model has been run
for a variety of different locales, and a variety of different conditions,
with reasonable results.

C-1

APPENDIX C: GLOSSARY OF ABBREVIATIONS

AFOS Automation of Field Operations and Service
ALERT - Automated Local Evaluation in Real Time
ASERT - Automated State Evaluation in Real Time
BW - Bureau of Waterways (DOT)
CAFW - Committee on Automated Flood Warning
CERC- Coastal Engineering Research Center (Corps of Engineers)
COE - U.S. Army Corps of Engineers (DOA)
CSP - Connecticut State Police
DEP - Department of Environmental Protection (CT)
DOC - Department of Commerce (US)
DOT - Department of Transportation (CT)
EPA - Environmental Protection Agency
FEMA - Federal Emergency Management Agency
FIRM - Flood Insurance Rate Map
FIS - Flood Insurance Study
GOES - Geostationary Operational Environmental Satellite
IEMIS - Integrated Emergency Management Information System
LIS - Long Island Sound
MAPONY - Maritime Administration, Port of New York
MEOW- Maximum Envelope of Water
MHW - Mean High Water
MLLW - Mean Lower Low Water
MLW - Mean Low Water
MSL - Mean Sea Level
NAS - National Academy of Sciences
NAWAS - National Warning System
NERFC - Northeast River Forecast Center (NWS, NOAA)
NGVD- National Geodetic Vertical Datum (1929 datum)
NGWLMS - Next Generation Water Level Monitoring System
NMS - National Meteorological Center (NWS, NOAA, DOC)
NOAA - National Oceanic and Atmospheric Administration (DOC)
NOS - National Ocean Service (NOAA, DOC)
NRC - Natural Resources Center (DEP)
NWLON - National Water Level Observation Network
NWR - NOAA Weather Radio
NWS - National Weather Service (NOAA, DOC)
OCP - Office of Civil Preparedness (CT)
SCS - Soil Conservation Service (DOAg)
SIO - Scripps Institute of Oceanography
SLOSH - Sea, Lake and Overland Surges from Hurricanes
SPLASH- Special Program to List Amplitudes of Surges from Hurricanes
TDL - Techniques Development Laboratory (NWS, NOAA, DOC)
UCONN - University of Connecticut
UHF - Ultra High Frequency
USGS - U.S. Geological Survey (U.S. Dept. of the Interior)
VHF - Very High Frequency
WHOI - Woods Hole Oceanographic Institution
WRU - Water Resources Unit (DEP)
WSFO - Weather Service Forecast Office
WS 0 - Weather Service Off ice

D-1

APPENDIX D: REFER ENCES

1. Hicks, Steacy D. 1983. Sea Level Variations for the United States,
1855-1980. National Ocean Service, NOAA, U.S. Dept. of Commerce.
2. Hicks, Steacy D. 1984. Tide and Current Glossary. National Ocean Service,
NOAA, U.S. Dept. of Commerce.
3. Hicks, Steacy D. 1980. The National Tidal Convention of 1980. National
Ocean Service, NOAA, U.S. Dept. of Commerce,
4. Swanson, Robert L. 1974. Variability of Tidal Datums Accuracy in Deter-
mining Datums from Short-Series of Observations. NOAA Technical Report
NOS 64. National. Ocean Survey, NOAA, U.S. Dept. of Commerce.
5. Coastal Area Management. 1977. Long Island Sound: An Atlas of Natural
Resources. Dept. of Environmental Protection, Hartford, CT.
6. U.S. Army Corps of Engineers. 1980. Tidal Flood Profiles, New England
Coastline. Hydraulics and Water Quality Section, New England Division.
7. National Ocean Service. 1984. Tide Tables: 1985 High and Low Water
Predictions, East Coast of North and South America, Including Greenland.
.NOAA, U.S. Dept of Commerce.
8. Aubrey, D.G. and K.O. Emery. 1983. Eigenanalysis of Recent United
States Sea Levels. Cont. Shelf Research, v. 2, p. A-33.
9* Hoffman, John S.,_ et.al. 1983. Projecting' Future Sea Level Rise: Metbo-
dology, Estimates to the Year 2100, and Research Needs. U.S. Environ-
mental Protection Agency.
10. Revelle, R. 1983. "Probable Future Changes in Sea Level Resulting
from Increased Atmospheric Carbon Dioxide," from Changing, Climate.
Carbon Dioxide Assessment Committee, National Aca demy of Sciencies,
Washington, DC, National Academy Press. .
11. U.S., Army Coastal Engineering Research Center. 19 77. Shore Protection
Manual, Volume 1. Corps of Engineers, Dept. of the Army.
12. New England Division. 1976. Connecticut Coastline Study: Effects
of Coastal Storms. U.S. Army Corps. of Engineers.
13. Bohlen, W.F., and K.B. Winnick. 1983. A Survey of, Surface Waves in
Long Island Sound. Prepared for the State of Connecticut, Department
of Environmental Protection, Hartford.
14. Hardy, C.D. Marine Sciences Research Center, State University of New
York, Stony Brook, NY.
15. Crowley, Cliff, Meteorologist In Charge,-New York WSFO, NWS. Personal,
communication, 2/13/85 and subsequen t.
16. Federal Emergency Management Agency. 1983 1985. Flood Insurance
Studies; Wave. Height Analysis 'Supplements, for Connecticut coastline
communities, Greenwich to Stonington.
17. Hobbs, Carl H. 1970. Shoreline orientation and storm surge. Maritime
Sediments 6:113-116.
18. Harris, D.L. 1963. Characteristics of the Hurricane Storm Surge.
U.S. Weather Bureau, Washington D.C., Tech. Paper No. 48
19. Gentry, R.C. 1966. Nature and Scope' of Hurricane Damage. Pages 229-254
in S.A. Stubbs ed. Hurricane Symposium, American Society of Oceanography,
Houston.
20. Frazier, Quartermaster First Class, Long Island Sound Group, Coast Guard,
New Haven. Personal communication, 9/6/85.

D-2

21. Boutilier, Carl, Chief, Navigation Branchq New England Division, U.S. Army
Corps of Engineers. Personal communication, 10/3/85.
22. Warner, Captain Ken, President, Northeast Marine Pilots, Inc., Newport,
RI. Personal communication, 9/6/85.
23. Monks, Captain Donald, New Haven- Bridgeport Pilots Association, Milford,
CT. Personal communication, 9/9/85.
24. Water Resources Support Center. 1983. The Ports of Southern New England:-
Providence, RI, Fall River, MA, New London, New Haven, & Bridgeport,
CT. Port Series No. 4, U.S. Army Corps of Engineers.
25. Vaukus, Jim, Manager, Stamford Hurricane Barrier, U.S. Army Corps of
Engineers, Stamford, CT. Personal communication, 2/20/86 and subsequent.
26. O'Baragan, Mike, Facilities Group, National Geodetic Information Center,
NOS, NOAA, U.S. Dept. of Commerce. Personal communication, 12/5/84.
27. Deibel, Lawrence E., and Barbara A. Zumwalt. 1985. Next Generation
Water Level Measurement System Program. By The Mitre Corporation
for National Ocean Service, NOAA, Dept. of Commerce.
28. Tidal Bench Marks. Connecticut, New London. 1968. Coast and Geodetic
Survey, Environmental Science Services Administration, U.S. Dept. of
Commerece.
29. Tidal Bench Marks. Connecticut, Bridgeport. 1968. Coast and Geodetic
Survey, Environmental Science Services Administration, U.S. Dept. of
Commerce.
30. Lyles, Steve, Tidal Datum Section, National 'Ocean Service, NOAA, U.S.
Dept. of Commerce. Personal communication, 8/26/85.
31. Dennam, Robert, National Ocean Service, NOAA, Dept. of Commerce, Bridgeport,
CT. Personal communication, 2/85.
32. Gillette, Earl, Meteorologist in Charge, Bridgeport WSO, NWS, Stratford,
CT. Personal communication, 2/13/85 and subsequent.
33. Williams, Burt, Electronics Technician, Bridgeport WSO, NWS, Stratford,
CT. Personal communication, 11/28/84 and subsequent.
34. St. Clair, J.M. 1985. National Weather Service memorandum on Technical
Information Package - Installation of the Data Collection Platform
Handar (DCPH) System (Telephone Type). NWS, NOAA, U.S. Dept. of Commerce,
Silver Spring, MD.
35. Thomas, C.E., et.al. 1983. Water Resources Data Connecticut: Water
Year 1982. U.S. Geological Survey Water-Data Report CT-82-1. Water
Resources Division, U.S. Geological Survey, Hartford. 1
36.. Cervione, Mike, Water Resources Division, USGS, Hartford, CT. Personal
communication, 8/9/85 and subsequent.
37. Shepard, Tom, Water Resources Division, USGS, Hartford, CT. Personal
communication, 8/9/85 and subsequent.
38. Rigatti, George, Water Resources Division, USGS, South Windsor, CT. Personal
communication, 2/21/86 and subsequent.
39. Mirick, Robert, Reservoir Control Center, New England Division, U.S. Army
Corps of Engineers, Waltham, MA. Personal communication, 10/11/85.
40. Finigan, Joseph,. Chief, Reservoir Control Center, New England Division,
U.S. Army Corps of Engineers,, Waltham, MA. - Personal communication,
3/5/86.
41. National Ocean Service. 1985. Index of Tide Stations: United States
of America and Miscellaneous Other Locations (Rough Draft).. NOAA,
U.S. Dept. of Commerce.
42. Dunn, Gordon E., and Banner 1. Miller. 1960. Atlantic Hurricanes.
Louisiana State University Press.
43. Neumann, Charles J., et.al. 1981. Tropical Cyclones of the North Atlantic

D-3

Ocean, 1871-1980 (with updates through 1984). National Climatic Center,
NWS, Asheville, N.C.
44. Neumann, C.J. and M.J. Pryslak. 1981. Frequency and Motion of Atlantic
Tropical Cyclones. NOAA Technical Report NWS 26. National Hurricane
Center, Coral Gables, FL.
45. L.ong Island Regional Planning Board. 1984. . Hurricane Damage Mitigation
Plan for the South Shore of Nassau and Suffolk Counties, New York.
Long Island Regional Planning Board, Hauppauge, NY.
46. Dewberry & Davis. 1982. Tidal Flood Profiles for the Connecticut Shoreline
of Long Island Sound. Prepared for the Federal Emergency Management
Agency.
47. New England Division. 1982. Regulation Manual, Stamford Hurricane Barrier,
.Stamford, Connecticut. U.S. Corps of Engineers, Waltham,.MA.
48. Mather, J.R., et.al. 1965. Coastal Storms of the Eastern United States.
Journal of Applied Meteorology, 3:693-706.
49. Federal Emergency Management Agency. 1980. Flood Insurance Study,
Town of Old Lyme, Connecticut.
50. Federal Emergency Management Agency. 1983. - Flood Insurance Study,
Supplement - Wave Height Analysis, Town of Old Lyme, Connecticut.
51. National Academy of Sciences. 1977. Methodology for Calculating Wave
Action Effects Associated with Storm Surges. Washington, DC.
52. Rummel, Cynthia J., and G.J. Hudak. 1984-1985. Flood Vulnerability
Assessment (for 24 coastal Connecticut municipalities). Natural Resources
Center, Department of Environment Protection, Hartford,, CT.
53. Williams, Allan N., Natural Resources Center, Department of Environmental
Protection, Hartford, CT. Personal communication, 2/13/85 and subsequent.
54. National Weather Service. 1981. Automated Local Evaluation in Real
Time: A Cooperative Flood Warning System for Your Community. Hydrologic
Services Division, National Weather Service, Western Region, Salt
Lake City, UT.
55. Curtis, David C. 1980. Flash Floods Communities Can Help Themselves
Prepare. Presented at the 1980 NAR-ASAE Annual Meeting,,, Eastern Connee-
Iticut State College, Willimatic, CT.
56. Owen, James H., and M. Wendell. 1981. Implementation Aspects of Flood
Warning and Preparedness Planning Alternatives. Prepared for Institute
for Water Resources, Water Resources Support Center, U.S. Army Corps
of Engineers. Fort Belvoir, VA.
57. National Advisory Committee on Oceans and Atmosphere. 1983. The Nations's
River and Flood Forecasting and* Warning Service. A Special Report
to the President and the Congress. Washington, DC.
58. Owen, James H. 1979. Information for Local Officials on Flood Warning
Systems. Prepared for National Weather Service, NOAA, U.S. Dept. of
Commerce.
59. Hydrology Subcommittee of , the Federal Interagency Advisory Committee
on Water Data. 1985. Guidelines on Community Local Flood Warning
and Response Systems.
60. Oyekan, Taiwo A., and Jerry R. Rogers. 1983. Flood Forecasting/Warning
System for lbadan, Nigeria. Presented at American Water Resources
Association, International Symposium on Hydrometeorology. San Francisco,
CA.
61. Curtis, David C. President, International Hydrological Services, Sacramento,
CA. Personal communication, 2/85 and subsequent.
62. Curtis, David C. 1982. ALERT for Connecticut. Northeast River Forecast
Center, National Weather Service, Bloomfield, CT. Presented at the

D-4

Connecticut Flood Management Workshop, Meriden, CT.
-63. Lubbers, Mark. Director, Environmental Protection Board, Stamford,
CT. Personal communication,, 2/85 and subsequent. OF
64. Committee on Automated Flood Warning. 1985. Automated Flood Warning
in Connecticut: A Master Plan.
65. Soil Conservation Service. 1985. Connecticut Flood Warning,System,
Bidders Package. SCS, U.S. Dept. of Agriculture, Storrs, CT., in
cooperation with Department of Environmental Protection, CT.
66. Garlitz, Nancy M. 1985. "Automated Flood Warning Reduces Flood Damages",
Soil and Water Conservation News, Jan., 1985. pp 3-5.
67. Renn, Phillip. Water Resources Coordinator, Soil Conservation Service,
U.S. Dept. of Agriculture, Storrs, CT. Personal communication, 8/26/85
and subsequent.
68. Laro, Roland. Meteorologist in Charge, Hartford Weather Service Office,
NWS, Windsor Locks, CT. Personal communication, 2/27/86.
69. Thomas, Steven, Deputy Director, New York Weather Service Forecast Office,
NY,NY. personal communication, 9/26/85.
70. Duty Officer (individual unknOWD), U.S. Coast Guard, Long Island Sound
Group, New Haven, CT. Personal communication, 9/6/85.
71. Schaeffer, Wilson A., Techniques Development Laboratory, Office of Systems
Development, National Weather Service, Silver Spring, MD. Personal
communication, 1/22/85 and subsequent.
72. Jarvinen, Brian, National Hurricane Center, National Weather Service,
Coral Gables, FL. Personal communication, 1/24/85 and subsequent.
73. Pore, N.A., W.S. Richardson, and H.F. Perrotti. 1974. Forecasting Extra-
tropical Storm Surges for the Northeast Coast of- the United States.
NOAA Technical Memorandum NWS TDL-50, Washington, D.C., 68 Pp.
74. Baskerville, Robert, New York Weather Service Forecast Office, NY, NY. Per-
sonal communicationt 9/18/85.
75. Auciello, Jene, Boston Weather Service Forecast Office, Boston, MA. Personal
, communication, 10/11/85.
76. National Weather Service. 1981. NOAA Weather Radio. NOAA/ PA 76015.
77. Carter, Michael T. 1983. Probability of Hurricane/Tropical Storm Condi-
tions: A User's Guide for Local Decision Makers. Severe Weather
Branch, National Weather Service, NOAA, U.S. Dept. of Commerce.
78. L.R. Johnston Associates. 1983. Realizing the Risk: A History of
the June 1982 Floods in Connecticut. Prepared for the Natural Resources
Center, CT Department, of,E.nvironmental Protection.
79. Gibb,, Paul, Office of Civil Preparedness, Hartford, CT. Personal communi-
cation, 9/21/85 and subsequent.
80. Kusako, Herb, CT Office of Civil Preparedness, Region I, Fairfield,
CT. Personal communication, 10/17/85.
81. Melendez, Pedro, CT Office of Civil Preparedness, Region II, New Haven,
CT. Personal communication, 10/7/85.
82. Scelora, Anthony, CT Office of Civil Preparedness, Region IV, Colchester,
CT. Personal communication, 10/7/85.
83. Office of Civil Preparedness. 1981. Emergency Operations Plan. CT
Office of Civil Preparedness, Hartford, CT.
84.. Lappe, Kenneth, CT Office. of Civil Prparedness, Hartford, CT. Personal
communication, 10/18/85.
85. Conlea, Wilbur, Civil Preparedness Director, Danbury, CT. Personal
. communication, 10/17/85.
86. Darrow, Mary Ann, Civil Preparedness Director, Waterford, CT. Personal
communication, 10/17/85.

D-5

87. Johnson, Fred, Civil Preparedness Director, East Lyme,, CT. Personal
communication, 10/18/85.
880 Sawyer, Carl, Civil Preparedness Director, Town of Groton, CT. Personal
communication, 10/17/85.
89. U.S. Army Corps of Engineers, New England Division. 1974. Long Island,
Sound Interim Memo No. COE-2, Tidal Hydrology. Waltham, MA.
90. Richardson, William S. 1978. Extratropical Storm Surge Forecasts for
the U.S. East Coast. NWS Technical Procedures Bulletin No. 226.
91. Jelesnianski, C.P., 1972. SPLASH (Special Program to List Amplitudes
of Surges from Hurricanes), I. Landfall storms. NOAA Technical Memorandum,
NWSS TDL-46, 52 pp.
92. Jelesnianski, C.P., 1974. SPLASH- -Special Program to List Amplitude
of Surge from H urr icane-- Part 11--General track and variant storm
conditions. NOAA, Technical Memorandum, NWS TDL-52.
93. Jelesnianski, C.P., J. Chen, W.A. Shaffer, and A.J. Gilad, ND. SLOSH-
a hurricane storm surge f orecait model. Techniques Development Laboratory,
National Weather Service', NOAA, Silver Spring, MD.
94. National Weather Service, Technique's Development Laboratory. 1985 (Draft).
Untitled (Technical Description of SLOSH). Silver Spring, MD.
95. Wiggert' Victor, National Hurricane Center, National Weather Service,
Coral'Gables, FL. Personal Communication, 12/20/85.
96. Andress, Harold, Federal, Emergency Management Agency, Washington, DC.
Personal communication, 1/22/85 and subsequent.
97. Coleman, Rick, National Weather Service, Techniques Development Laboratory,
Silver Spring, MD. Personal communication, 1/22/85.
98. Titus, Temp. Testing g and Evaluation Section, National Weather Service,
. Silver Spring, MD. Personal communication, 9/85.
990 Gordon, R.B. and M.L. Spaulding, 1979. A nested, numerical tidal model
-of the southern New England bight. Ocean Engineering Dept., Univ.
of Rhode Island, N79-14698, 55 pp.
100. Spaulding, M.L. and R.B. Gordon, 1982. A nested numerical tidal model
of the southern New England bight. Ocean Engineering, v. 9, p. 107-126.
101. Spaulding, M.L., 1984. A vertically averaged circulation model using
boundary-f itted coordinates. J. Phys. Oceanog., v. 14, p. 973-982.
102. Braatz, B.V. and D.G. Aubrey, sutxnitted., Recent sea-level changes along
eastern North America.
103. Peltier, W.R., submitted. Deglaciation induced vertical motion of the
North American continent. Jour. Geopbys. Research.
104. U.S. Army Corps of Engineers. 1984. Shore Protection Manual, 4th ed.,
2 vols., U.S. Army' Waterways Experiment Station, Coastal Engineering
Research Center, U.S. Govt. Printing Off ice, Washington, D.C.
105. Graber, H.C., 1984. A parametric wind-wave model for arbitrary water
depths. Mass. Inst. Tech., Doctoral Thesis, Cambridge, MA, 310 pp-
National Academy of Sciences. 1977. Methodology for Calculating Wave
Action Effects Associated with Storm, Surge. Washington, DC.
107. Leupold& Stevens, Inc. 1978. Stevens Water Resources Data Book. Beaverton,
OR.
108. U.S. Coast and Geod etic Survey. 1977. Manual of Tide Observations. Publi-
cation 30.1.
109. Mero,, Thomas N'., and Alfred Zulueta. 1979. Water Level Measurement
Systems Technology Survey. National Ocean Survey, Test and Evaluation
Laboratory.
.110. Various product descriptions' and specification sheets from numerous
vendors find manufactures.

D-6

111. Bartex, Inc. 1985. Product descriptions and specifications for AQUATRAK
1100 and 2000 acoustic tide gage.
.112. Barnes, Harry, President, Bartex, Inc. Personal I communication, 1/22/85
and subsequent.
113. Mero, T.N., 1981. Aquatrak model LG-1100 water level gage operating
range and fouling effects. NOAA ESO Teeb. Report TES-81-010, 5 pp.
114. Libraro, P.J., 1980. Evaluation of the Aquatrak model LG-1101-01 precision
water level measurement system. NOAA ESO Technical Report TE3-81-002.
115. Seymour, Richard J., M.H. Sessions, and David Castel. 1985. Automated
Remote Recording and Analysis of Coastal Data. Journal of Waterway,
Port, Coastal and Ocean Engineering, Vol. 111, No.. 2.
116. Colton, Donald E., Vice President, Systems Development, International
Hydrological Services, Sacramento, CA. Personal communication, 2/86.
117. Holland, Mel, Handar, Inc., Sunnyvale, CA. Personal communication,
9/19/85.
118. Federal Emergency Management Agency. 1984. A Guide for Hurricane Prepar-
edness Planning for State and Local Officials. CPG 2-16.
119. Fach, Skip, U.S. Army Corps of Engineers, Baltimore, MD. Personal commun-
ication, 12/10/85.
120. Hughes,, Rebecca, Water Resources Administration, Maryland Department
of Natural Resources, Annapolis, MD. Personal communication, 2/85
and subsequent.
121. Sharrocks, Fred, Federal Emergency Management Agency. Personal communication,
10/8/85 and subsequent.
122. Old, Kenneth, B., U.S. Army Engineer District,, Flood Plain Management
Branch, Wilmington, NC. Personal communication, 12/85.
123. Hess, Richard, National Ocean Service. Personal communication, 1/17/85.
124. Lapine, Louis, National Ocean Service. Personal communication, 9/10/85
and subsequent.
125. Hays, John, National Ocean Service. Personal communication, 10/28/85.
126.- McCarthy, Kevin, Meteorologist, Eastern Region Headquarters, National
Weather Service, Garden City, NY. Personal communication, 2/14/85.
Handar, Inc. 1984. Operating and Service Manual for 540A Multiple
Access Data Acquisition System, 560A Hydrologic Data Collection System,
and 545A Programming Set. Sunnyvale, CA.
128. Scbiesl, Joseph, Date Systems, National Weather Service. Personal communi-
cation.
129. Jaske, Robert, Federal Emergency Management Agency. Personal communication,
10/18/85.
130. Federal Emergency Management Agency. 1984. Computer Capabilities Developed
for Integrated Emergency 'Management Information Program. FEMA Newsletter,
Nov/Dee, 1984.
131. Federal Emergency Management Agency. 1985. More about IEMIS. FEMA
Newsletter, May/June, 1985.
132. Jaske,RobertT. 1985. FEMA's Integrated Emergency Management Information
System OEMIS). Proc. American Meteorological Society, Jan. 8, 1985.
133. Federal Emergency Management Agency. 1985. Integrated Emergency Management
Information System (IEMIS): Development and Deployment Plan (Draft).
134. Melendez, Pedro, Connecticut Office of Civil Preparedness, Hartford,
CT. Personal communication, 10/7/85.
135.. Castel, David, Scripps Institute of Oceanography, La Jolla, CA. Personal
communication, 2/20/86 and subsequent.
136. Lilly, Kenneth, Chief Meteorologist, Marine Services, Meteorological
Services Division, Western Region Headquarters, National Weather Service,

D-7

Salt Lake Ci tyl, UT. Personal communication, 2/20/86.
137. U.S. Army Corps of Engineers, and California Department of Boating and
Waterways. 1986. Coastal Data Information Program, Monthly Report,
December 1985. Monthly Summary Report No. 119.
138. Seymour, R.J., et. al. 1985. Coastal Data Information Program, Ninth
Annual Report, January 1984 through December 1984. Scripps Institute
of Oceanography, La Jolla, CA.
139. Lilyquist, Alan, Coastal Resources Specialist, New York Depar 'tment of
State, Albany, NY. Personal Communication, 3/85 and subsequent
140. Canata, Barbara, The Maritime Association of the Port of New Tork, New
York, NY. Personal communication, 3/l/85 and subsequent.
.141. Cretan, Nick C., The Maritime Association of the Port of New @ York, New
York, NY. Personal communication, 3/15/85 and subsequent.
142@. The Maritime Association of. the Port of New York. Undated. Tidal Gauge
System. (unpublished program description)
143. Prindiville, William,. Manager, Vessel bperations, Sea-Land Service,
Inc., Elizabeth, NJ. Personal communication, 3/20/85 and subsequent.
144. New York State Department of State. Undated. The Tidal Gauge System
. (brochure).
145. Visel, Tim, Connecticut Marine Advisory Service, Marine Sciences Institute,
Groton, CT. Personal communication, 10/3/85.
146. Peters, Captain Tom, Sandy Hook Pilots Association, Sandy Hook, NJ. Personal
communication, 9/23/85.
147. Becker, Captain George, Sandy Hook Pilots Association, Sandy Hook, , NJ.
Personal communication, 9/24/85.
148.@ Kramer, George, McAlister Brothers, Inc.,. New York, NY. Personal communi-
cation, 9/23/85.
149. Curll, Dan, American Waterway Operators Association, New York, NY. Personal
communication, 9/18/85.
150. Wolff, Paul M., and Dane Konop. 1984. Predicting Water Circulation
in Delaware Bay and Riverr NOAA's New Approach. Sea Technology, Sept. 1984.
151. Mellor, G.L., Geophysical Fluid Dynamics Program,. Princeton University,
Princeton, NJ. Personal communication, 1/86.
Perkins, Don, Assistant Executive D ir ector, Marine Board, National Research
Council, National Academy of Sciences, Washington, DC. Personal commurk.-
ication, 2/21/86.
153. Stoll, Jeffrey L 1983. Accomodating the Tides. Surveyor, May, 1983,
pp. 16-21.
154. Guth, Jack, Pres'identj Sea and Meteorology, Inc., Herndon, VA. Personal
communication, 1/10/85 and subsequent.
155. Sea and Meteorology, Inc'. Undated. Technical, Description of real-time
tide and wind gage system.
156. Dunlap, Craig. 1984. Computerized harbor Gauges Advocated. The Journal
of Commerce, May 1, 1984.
157. Hazen, Frank, President, Hazen Tide Gauge International, Tacoma, WA. Personal
communication, 1/10/85 and subsequent.
158. Howell, Gary. 1980. Florida 'Coastal Data Network. Proceedings of the
Seventeenth Coastal Engineering Conference, Volume 1, pp. 421-431.
159. Howell, Gary L. 1978. A Microprocessor Based Underwater Data Acquisition
System. Coastal & oceanographic Engineering Department, College of
Engineering, University of Florida, Gainesville, FL.
160. Metha, Dr., College of Engineering, University of Florida, Gainesville,
FL. Personal communication, 10/10/85.

D-8

161. Perlin, Mark, College of Engineering, University of Florida, Gainesville,
FL. Personal communication, 10/10/85.
162. Howell, Gary L., U.S. Army Corps of Engineers, Coastal Engineering Research
Center, Vicksburg, MS. Personal communication, 10/10/85. -
163. Guice, Wade, Director, Harrison County Civil Defense, Gulfport, MS. Personal
communication, 9/18/85 and subsequent.
164. Harrison County Civil Defense Council. 1985. Harrison County Water
Level Monitoring System, Requirements Specifications (Draft). Gulfport,.
MS.
165. N.B.A. (Controls) Ltd. 1985. Dial-a-Surge. Current Affairs, The Newsletter
of NBA (Controls) Ltd., Autumn . 185.
166. Synergetics International, Inc. 1984. Synergetics Awarded Contract
for Ganges River/Bay of Bengal Installation. How GOES It? (Synergetics
Newsletter) . Boulder, CO.
167. Synergetics International, Inc. 1985. Experience Profile. Boulder,
CO.
168. Andress, Bud. 1985. The Federal Emergency Management Agency (FEMA)
Hurricane Preparedness Program. Presented at the "Cities on the Beach"
Conference on the Management of Developed Coastal Barriers. Jan. 17,
1985, Virginia Beach, VA.
169. Bray, William, Civil Preparedness Director, -Fairfield, CT. Personal
communication, -2/13/85.
170. Healey, Chief, Civil Preparedness Director, Milford, CT. Personal communi-
cation, 2/13/85.
171. Federal Insurance Administration, Federal Emergency Management Agency. 1981 "
Field Manual for Estimating Wave Heights in Coastal High Hazard Areas
in Atlantic and Gulf Coast Regions.
172. Federal Insurance Adm 'inistration, Federal Emergency Management Agency.
1981. Users Manual for Wave Height Analysis.
173. National Academy of Sciences. 1977. Methodology for Calculating Wave
. Action Effects Associated with Storm.Surges.
174. Various oceanographic researchers. Personal communication.
175. Sessions, Meredith, Scripps Institute of Oceanography, La Jolla, CA. Personal
communication,, 3/11/85.
176. Roper, Ted, Sales Manager, Sierra Misco, Inc., Berkely, CA. Personal
communication, 3/11/86.
177. Smith, Robert, Assistant Director, Planning Section, Water Compliance
Unit, CT Department of Environmental Protection, Hartford, CT. Personal
communication, 10A7/85 and subsequent.
178. Stacey, Paul, Environmental Analyst, Planning Section, Water Compliance
Unit, CT Department of Environmental Protection, Hartford, CT. Personal
communication, 3/11/86.
179. Morrissey, Tom, Senior Sanitary Engineer, -Planning Section, Water Compliance
Unit, CT Department of Environmental Protection, Hartford, CT. Personal
communication, 3/11/86..
180. Conel Cellular, Inc., Norwalk, CT. Personal communication, 3/11/86.
181. Morton,, Bohlen, and Aubrey. 1985.
182. Vitello, Petty Officer, Aides -to Navitation Team, Long Island Sound'
Group, U.S. Coast Guard,. New Haven, CT. Personal communication, 3/5/86.
183. Schillumeit, Cheif, Aides to Navitation Team, Long Island Sound Group,
U.S. Coast Guard, New. Haven, CT.. Personal communicaffion, 3/7/86.
184. Renn, Phillip A. 1986., Minutes of February 3, 1986 meeting of the
Committee on Automated Flood Warning.. Soil Conservation Service,
Storrs, CT.

D-9

185. Mendell, Todd, Flash Flood Hydrologist, Northeast River Forecast Center,
National Weather Service, Bloomfieldt CT. Personal communication,
10/2/85 and subsequent.
186. Tabaco, Joe, ADP Manager, Eastern Region Headquarters, National Weather
' Service, Garden City, NY. Personal communication, 2/27/86.
187. Boon, J.D., C.S. Weleb, H.S. Chen, R.J. Lukens, C.S. Fang@ and J.M.
Zeigler, 1978. Storm surge height-f requency. analysis and model prediction
for Chesapeake Bay. Special Report no. 189, volume 1, Virginia Insitute
of Marine Science, Gloucester Point, VA., 155 pp.
188. Wilson, B.W., 1957. Hurricane Wave statistics for the Gulf of Mexico.
Beach Erosion Board, Department of the Army, Technical Memorandum
No. 98.
189. Niboul, J.C.J. (ed.), 1979. Marine for ecasting-- predictability and
modelling in ocean hydrodynamics. Elsevier, Amsterdam, 493 pp. ,
190. Pagenkopf, 'J.R. and B ,R. Pearce, 1975. Evaluation of techniques for
numerical calculation of storm surges. Massachusetts Institute of
Technology, Ralph M. Parsons* Laboratory for Hydrodynamics, Report
no. 199, 120 pp.
191. Pearce, B.R., 1972. Numerical calculation of the response of coastal
waters to storm systems Tech. Report no. 12, Coastal and Oceano-
graphic Engineering Lab, bniv. of Florida, Gainesville, FL.
192. Connor, J.J. and JX. Wang, 1973. Mathematical models of the Massachusetts
Bay, Part 1: Finite element modeling of two-dimensional hydrodynamic
circulation. Tech. Report no. 172, Ralph M. Parsons Laboratory.
193. Wang, J.D. and J.J. Connor, 1975. Mathematical modeling of near coastal
circulation. Mass. Institute of Technology, Ralph M. Parsons Laboratory
Technical Report no.,MITSG-75-13.
194. Thacker, W.C., 1977. Irregular grid finite-difference techniques: simula-
tions of oscillations in shallow circular basins. J. Phys. Ocean.,
v. 7, p. 284-292. Thacker, W.C., 1977. Reply. Jour. Phys. Oceanog.,
v. 7, p. 933-934.
195. Wang, J.D., 1977. Comments on "Irregular grid finite-difference tech-
niques: simulations - of oscillations in shallow circular basins". Jour.
Phys. Oceanog., v. 7, p. 932-933.
196. Johnson, B.H., -1982., Numerical modeling of estuarine hydrodynamics
on a boundary fitted coordinate system. Numerical Grid Generation,
J. Thompson (ed.), Elseviero p. 409-436.
197. Thompson, J.F., F.C. Thames, and C.W. Mastin, 1977. TOMCAT--a code
for numerical generation of boundary-fitted curvilinear coordinate
systems on fields containing any number of arbitrary two-dimensional
bodies. Jour. Computational Physics, v. 24, p. 274-302.
198. Thacker, W.C., 1978. Comparison of finite-element and finite-difference
schemes. Part 1: one-dimensional gravity wave motion. J. Phys. Oceanog.,
v. 8, p. 284-292.
199. Thacker, W.C., 1978. Coomparison of finite-element and finite-difference
schemes. Part 11: Two-dimensional gravity wave motion. J. Phys.
Oceanog., v. 8, p. 680-689.
200. Grant, W.D. and O.S. Madsen, 1979. Combined wave and current interaction
with a rough bottom. Jour. Geop .hys. Re .search, v. 84, p. 1797-1808.
201. Grant, W.D. and O.S. Madsen, 1982. Movable bed roughness in unsteady
oscillatory flow. Jour. Geophys. Res., v. 87, p. 469-481.

202. Reid, R.O. and B.R. Bodine, 1968. Numerical model for storm surges
in Galves ton Bay. Jour. of the Waterways and Harbors Division, ASCE,

D-10

V. 94, WWI, Proc. Paper 5805, 33-57.
-203. Chapman, D.C., in press. On, the numerical treatment of cross-sbelf
open boundaries in a barotropic coastal ocean model. Jour. Physical
Oceanography.
204. Laevastu, T. and R. Callaway, 1974. Computation of. tides, currents,
and dispersal of pollutants in New York Bight from BIS to Atlantic
City with large grid size, single and two-layer hydrodynamieal numerical
models. Envi. Pred. Res. Fac., Naval Post Grad. School, Monterey,
CA, Tech note 4-74.
205. Leendertse, J.J. and S.K.Liu, 1977. A three dimensional model for estuarine
and coastal seas, IV: Turbulent energy calculation. . Rand Corp., Santa
Monica, CA. Report R-2187-OWRT.
206. Beauchamp, C.H. and IVI.L. Spaulding, 1978. Tidal circulation in coastal
seas--verification of mathematical and physical models in hydraulic
engineering. Proc. of the 26th Ann. Hydraulics Div. Specialty Conf.,
ASCE, p. 518-528.
207. Murphy, M., 1978. Personal communication referenced in Spaulding and
Gordon, 1982 (100).
208. Jelesnianski, C.P., 1970. Bottom stress time-history in linearized
equations of motion of storm surge. Monthly weather review, v. 98,
p. 462-478.
209. Sverdrup, H. and W. Munk, 1947. Wind, sea and swell: Theory of Relations
for forecasting. Hydrograpbic Bureau Publication 601. U.S. Navy
Hydrographic Office, Washington, D.C. 44 pp. + appendices.
210. Pierson, W.J, L.J. Tick and L. Baer, 1966. Computer based procedures
for preparing global wave forecasts and wind field analysis capable
of using vave data obtained from spacecraft, in Proceedings of 6tb
Symposium on Naval Hydrodynamics, Washington, D.C., 499 pp.
211. SWAMP, 1985. Ocean Wave Modeling. Plenum Press, NY, 256 pp.

I
I
I
I
1.
I
I
I
.1
1.
I
I
.11
I

I
I
1

3 6668 14100 9482