Environmental atlas and multiuse management plan for south-central Louisiana

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

Coastal Zone
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1973

REPORT 18 CENTER FOR WETLAND RESOURCES
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VOLUME 1 LOUISIANA STATE UNIVERSITY
BATON ROUGE

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CENTER FOR WETLAND RESOURCES
Louisiana State University
Baton Rouge, La. 70803

HYDROLOGIC AND GEOLOGIC STUDIES
OF COASTAL LOUISIANA

Environmental Atlas and Multiuse Management Plan
for South-Central Louisian/
Report No. 18
Volume I

LIN

By
Sherwood M. Gagliano - Project Director
and
Penny Culley
Daniel W. Earle, Jr.
Peggy King
Curtis Latiolais
Phillip Light
Alice Rowland
Roy Shlemon
Johannes L. van Beek

October, 1973

Prepared for

Department of the Army, New Orleans District
Corps of Engineers, Contract No. DACW 29-71-C-0219

and

Office of Sea Grant, National Oceanic and Atmospheric
Administration of U. S. Department of Commerce,
Institutional Support Grant No. 04-3-158-19

ABSTRACT

The normally difficult problems of resource management and land

use planning are further complicated in the coastal zone by the complex-

ity of the natural setting, rich resource base, and trends of population

increase. The Louisiana coast, dominated by the Mississippi River delta

system, illustrates the classic elements of the problem. The area is

exceptionally high in biological productivity. Unique natural beauty and

a rich cultural heritage further identify these lowlands as a nationally

important resource. As the origin and ecology of the region are products

of deltaic processes, it can appropriately be described as a self-

maintaining natural system.

Human activity has seriously altered the natural balance of this

system. Massive environmental degradation has occurred during the past

thirty years and the entire system may soon collapse. Primary causes of

deterioration include: 1) flood control and navigation improvement;

2) mineral extraction; 3) accelerated subsidence; 4) urban encroachment

into wetlands; 5) water pollution.

The problem of restoring the system's balance while allowing for

projected growth and development has been addressed, and a multiuse

management plan, based on analysis of natural and human processes

operating in the area and land use suitability, has been proposed.

Highways and other public works projects provide the mechanism for

directing growth and development to environmentally suitable areas.

Renewable resource areas are identified, and management priorities and

guidelines outlined. A water resource management program calls for

conservation of local runoff as well as directing the Mississippi River

water and sediment for environmental maintenance and enhancement.

CONTENTS

Page
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . vii

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 1

APPROACH . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Background of Study . . . . . . . . . . . . . . . . . . . . 5
Environmental and Land Use Atlas . . . . . . . . . . . ... 9
Grid Cell Data Collection and Display . . . . . . . . . . . 13
Hydrologic Models . . . . . . . . . . . . . . . . . . . . . 14
Use of Remote Sensing Imagery . . . . . . . . . . . . . . . 21
User Input . . . . . . . . . . . . . . . . . . . . . . . . . 23

NATURAL SETTING . . . . . . . . . . . . . . . . . . . . . . . . . 24

Evolution . . . . . . . . . . . . . . . . . . . . . . . . . 24
The Terrebonne Subsystem . . . . . . . . . . . . . . . . . . 24
The Barataria Subsystem . . . . . . . . . . . . . . . . . . 28
Environmental Differentiation . . . . . . . . . . . . . . . 29
Barrier Islands . . . . . . . . . . . . . . . . . . . . . . 36
Subsurface Characteristics . . . . . . . . . . . . . . . . 37
Natural Deterioration and the Delta Cycle . . . . . . . . . 43
Subsidence . . . . . . . . . . . . . . . . . . . . . . . . 45
Marsh Opening . . . . . . . . . . . . . . . . . . . . . . . 49
Lakeshore Erosion . . . . . . . . . . . . . . . . . . . . .. 51
Fresh-Salt Water Mixing . . . . . . . . . . . . . . . . . . 57
The Delta Cycle . . . . . . . . . . . . . . . . . . . . . . 59

MANAGEMENT OF NATURAL PROCESSES AND HUMAN ACTIVITIES . . . . . . 64

MANAGEMENT PLAN . . . . . . . . . . . . . . . . . . . . . . . . . 75

Management and Development Areas . . . . . . . . . . . . . . 75
Barrier Island, Reef, and Gulf Shore Areas . . . . . . . . . 76
Estuarine Nursery Areas . . . . . . . . . . . . . . . . . . 79
Fresh-Brackish Marsh Areas . . . . . . . . . . . . . . . . . 80
Freshwater Basins . . . . . . . . . . . . . . . . . . . . . 81
Development Corridors . . . . . . . . . . . . . . . . . . . 82
Geometry for Development . . . . . . . . . . . . . . . . . . 85
Surface Water Resource Management . . . . . . . . . . . . . 89
Environmental Engineering . . . . . . . . . . . . . . . . .. 92
Conflicts . . . . . . . . . . . . . . . . . . . . . . . . .. 102

Page
SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . 105

APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix A. List of Remote Sensing Data from
the Study Area . . . . . . . . . .. . . . . . . . . . 109
Appendix B. Agencies and Groups Consulted
During Study . . . . . . . . . . . . . . . . . . 119

REFERENCES . . . . . . ... . . . . . . . . . . . . . . . . . . 127

FIGURES

Fi,fyure Page
1-1. South-central Louisiana study area and
its relationship to the Louisiana coastal zone 2

2-1. Schematic cross-section showing land-use
suitability and limitations of natural environments
of Barataria-Terrebonne area . . . . . . . . . . . . . . 11

3-1. Delta lobes formed by the Mississippi River
during the past 6,000 years . . . . . . . . . . . . . . 25

3-2. Chronology of delta lobes as determined by
radiocarbon dating of deltaic plain peat
deposits . . . . . . . . . . . . . . . . . . . . . . . . 26

3-3. Transect showing transition from natural
levee oak forest to cypress-gum swamp, to
fresh water marsh . . . . . . . . . . . . . . . . . . . 30

3-4. Transect showing transition from natural
levee oak forest to brackish marsh through
a shrub and cane zone . . . . . . . . . . . . . . . . . 30

3-5. Schematic cross-section of flora associated
with the natural environment of the Barataria-
Terrebonne area . . . . . . . . . . . . . . . . . . . . 31

3-6. Schematic cross-section of fauna associated
with the natural environment of the Barataria-
Terrebonne area . . . . . . . . . . . . . . . . . . . . 32

3-7. Distribution of flotant . . . . . . . . . . . . . . . . . 35

3-8. Shoreline changes of delta margin islands
in the abandoned Lafourche Delta system,
1890-1960 . . . . . . . . . . . . . . . . . . . . . . . 38

3-9. Profile showing buried marsh layer along
proposed Houma Ship Channel . . . . . . . . . . . . . . . 40

3-10. Typical section in floating marsh or
flotant about 22 miles south of New Orleans . . . . . . 41

3-11. Geomorphic features and sedimentary deposits
in the abandoned Lafourche Delta complex . . . . . . . . 42

3-12. Shoreline changes in the abandoned Lafourche
Delta complex, 1845-1947 . . . . . . . . . . . . . . . . 46

3-13. Marsh deterioration as a result of subsidence . . . . . . . 48

3-14. Linear lakes between beach ridges near the
mouth of Bayou Lafourche . . . . . . . . . . . . . . . . . . 50

3-15. Lake shore retreat and opening up of
floating marsh, Barataria Basin . . . . . . . . . . . . . . 52

3-16. Shore retreat along round lakes, Barataria Basin . . . . . . 53

3-17. Flooding associated with the passage of Hurricane
Hilda, October, 1964 . . . . . . . . . . . . . . . . . . . . 56

3-18. Fresh and salt water mixing zone in the Barataria
Bay-Lac des Allemands estuary system . . . . . . . . . . . . 58

3-19. Distribution of major environments in the
Barataria-des Allemands estuary system . . . . . . . . . . . 60

3-20. Relationship between biological productivity
and the delta cycle . . . . . . . . . . . . . . . . . . . . 61

4-1. Submerged fields, Barataria Basin . . . . . . . . . . . . . 68

4-2. Submerged fields, Barataria Basin . . . . . . . . . . . . . 69

5-1. Major elements for growth and development
of the Louisiana coastal zone . . . . . . . . . . . . . . . 86

5-2A. Preliminary water needs for salinity alteration
and/or water level management, Hydrologic Unit IV . . . . . 91

5-2B. Preliminary water needs for salinity alteration
and/or water level management, Hydrologic Unit V . . . . . . 91

5-3. Schematic plan for environmental management and
land use at intersection of freshwater drainage
canal and development corridor . . . . . . . . . . . . . . . 95

5-4. Configuration of proposed man-made barrier islands . . . . . 98

5-5. Generalized block diagram of Avery Island salt dome . . . . 101

TABLES

Table P ag e
3-1. Plant species composition, average soil-
water salinity, and acreage of marsh
zones within the Barataria-Terrebonne
wetlands . . . . . . . . . . . . . . . . . . . . . . 34

ACKNOWLEDGEMENTS

The support of the New Orleans District U. S. Army Corps of

Engineers and the Office of Sea Grant, National Oceanic and Atmos-

pheric Administration is gratefully acknowledged. Primary funding

was provided through Corps of Engineers Contract DACW 29-71-C-0219

for development of methodology and study of the Terrebonne Parish

pilot area. Supplementary funding, Office of Sea Grant, Institutional

Support Grant No. 04-3-158-19 made it possible to extend the scc)pe of

the project to include the des Allemands-Barataria Basin.

vii

INTRODUCTION

The Barataria-Terrebonne region of south central Louisiana

(Figure 1-1) comprises the most extensive and most productive natural

entity within the Louisiana coastal zone. It owes this productivity

to a viable estuarine environment, a subsurface rich in mineral de-

posits, and a topography that greatly facilitated access and allowed

for agricultural and industrial development. At the same time, beauty

of the natural setting of the area cannot be overemphasized. The natur-

al levee ridges, swamps, marshes, bayous, lakes, bays, and islands re-

present a unique coastal landscape that provides scenic open space and

unlimited opportunities for recreation. This potential is further en-

hanced by an abundance of archaeological and historic sites, and a rich

folk culture.

With regard to extended prosperity of the area, the estuarine

environment is its most important asset. A repetitive sequence of

delta building and abandonment has produced a series of estuaries whose

biologic productivity sustains a multi-million dollar commercial fish-

eries industry. Louisiana landings rank first nationally in volume and

third in value, with shrimp, menhaden, and oysters the dominant catches.

To a large extent, continuity of this resource is dependent on

quality and quantity of the estuarine nursery areas. In both respects,

the Barataria and Terrebonne estuaries rank among the highest, state

and nation-wide. However, viability of the nursery area is critically

dependent on a balance between fresh and salt water influx to Inain-

tain a desirable salinity regime, between erosion and deposition to

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Figure 1-1. Sout-h-c-mlra-I Louisiana study area and its reiationsnip to the Louisiana coastal zone.

maintain an optimum land-water ratio and length of land-water interface,
and on health of the marshes as a source of organic detritus and a deter-

rent to rapid areal increase of water bodies at the expense of the marsh-
lands. This dependence translates into a highly complex and highly vul-
nerable environment whose value as a resource can be maintained only

through recognition of both its potentials and limitations.

As documented by archaeological evidence, man has lived in the

Barataria-Terrebonne region for thousands of years. Until the early
twentieth century, technology and economic opportunities made his pre-

sence and activities compatible with his natural environment. Settle-

ment, industrial development, and land transportation patterns were

dictated by natural levee ridges. Regional centers, such as the city

of Houma, developed where major levees converged. The arable nature

of these same natural levees allowed the area to become an agricultural

center for sugar cane. The estuaries, as now, sustained a fisheries
industry, while natural waterways, including the Mississippi River,
adequately served water-borne transportation. With economic growth and

technologic progress came, however, the demands and possibilities for

flood protection, extraction of mineral deposits, land reclamation,
urban development, and transportation networks, and resulting oblit-

eration of natural boundaries and a dissection of natural entities.

In particular, the confinement of the Mississippi River, the

extraction of mineral deposits, and industrial and urban sprawl have

placed the wetlands under severe stress through modification of the

geologic and hydrologic regimes. Though unavoidably a part of

regional resource development, prevention of overbank flow from the

Mississippi River has deprived the estuarine system of needed sediment,

fresh water, and nutrients. At the same time, subsidence and wave erosion

continued to convert land into water, and saline Gulf waters continued

to intrude. Mineral extraction demanded a vast network of canals to

accommodate drilling operations and transport. Canal dredging again

modified the hydrologic and salinity regimes by reducing fresh water
diffusion, altering circulation patterns, and providing avenues for

salt water encroachment upon the brackish marshes. These as well as

other developments represent a serious conflict between exploitation of

renewable and nonrenewable resources. Insufficient recognition and

evaluation of this conflict threatens to sacrifice long-term benefits

for short term profits.

It is only through adherence to a sound long-term plan for land

use and resource development that the natural wealth of the coastal

zone can materialize to its full potential. Such a plan can be

established through detailed inventory of the natural environment,

identification of those elements and processes which make the area

unique and highly productive, and an evaluation of man's impact. on the

natural system. This approach is followed in the present study. On

the above basis,, the study has resulted in a series of guidelines for

resource exploitation and multi-use development of the Barataria-

Terrebonne region.

APPROACH

Background of Study

In the 1960's there was an increasing concern about environmental ef-

fects of a number of major projects proposed for the Louisiana coastal

zone. By 1969, in an effort to meet the challenge of maintaining a viable

natural setting and still responding to the demands of a highly industri-

alized and urbanized society, the New Orleans District Corps of.Engineers

initiated five studies of special environmental significance, the coastal

area being an important concern of each. In addition, the New Orleans

District chaired an interagency study, collectively referred to as the

Fish and Wildlife Study of the Louisiana Coast and Atchafalaya Basin

Floodway, which was related to and supported the five studies. The Center

for Wetland Resources, Louisiana State University, was retained by the New

Orleans District to undertake hydrologic and geologic studies as part of

the Fish and Wildlife Study. Following initial engagement in these in-

vestigations, the relationship has continued, and this report results from

the fourth in a series of contract studies addressing the general problem

of management and development of the coastal zone.

The studies have progressed through several distinctive phases.

Initial emphasis was on understanding the natural processes and forms of

the Mississippi Delta System as related to geology, ecology, hydrology,

water chemistry, water balance, and runoff, and the synthesis of avail-

able data. A primary objective was problem definition. Map and aerial

photo studies established rates and extent of land loss, marsh deterior-

ation, and coastal erosion, and demonstrated that the delta system, com-

prising most of the coastal zone, was generally in a serious condition of

deterioration. Contributing factors, both natural and man-induced, were

identified. Studies of salt water intrusion, as well as subsidence,

flood control, drainage projects, land reclamation, dredging, and

urban and industrial encroachment into the wetlands have led not only

to a better understanding of the environmental problems, but have also

provided the basis for management guidelines and the development of a

management plan. The initial plan is presented in this report and

follows creative approaches to environmental problems and future uses

of the coastal area.

Whereas previous work has dealt with macrosystems, primarily the

delta system of the Mississippi River, the present study has been con-

ducted at an intermediate scale. It focuses on two major hydrologic or

estuarine units which are subsystems of the delta. The Terrebonne

Parish area was selected for a pilot study of this assessment of the

coastal zone management problem because it was considered to be typical

of much of the Louisiana coast. It is also of particular interest be-

cause of high biological productivity and a relatively low level of

human impact. After the study was initiated, however, it became apparent

that management problems within the proposed study area were intimately

linked with those of neighboring lowlands. Supplementary support from

the Office of Sea Grant made it possible to expand the scope of the study

and include the entire area between the Mississippi River and the east

levees of the Atchafalaya Basin Floodway. It should again be empha-

sized that this is an intermediate scale study, and that there are

several levels of higher resolution in the planning hierarchy that

eventually must be considered.

Throughout the studies that have led to projection of a manage-

ment plan for south central Louisiana, emphasis has been placed on

development of a methodology for environmental evaluation. The subject

area of environmental evaluation has progressed significantly in recent

years, and the use of environmental data in planning is now a well-

accepted technique (see, for example, McHarg, 1969). The approach

recognizes that Louisiana's coastal zone is unique in both natural

landscape and cultural processes, and has used these inherent qualities

and values as a basis of projection.

The natural setting of the coastal zone of Louisiana can be summed

up in one word, "dynamic". The fact that the area is in a state of

constant flux causes many problems, but at the same time offers many

opportunities. The coastal environment is the product of interaction

between the deltaic-fluvial system of the Mississippi River and marine

forces of the Gulf of Mexico. Associated with incessant subsidence,

the interplay between deltaic and marine processes has resulted in a

highly diversified landscape of natural levees, swamps, marshes,

bayous, lakes, bays, and barrier islands, all in a changing and con-

stantly evolving relationship.

Changes are often so rapid and seemingly so complex that one

might view them as random and unpredictable, but that is not the case.

Over the years, a good understanding of the relationships between

process, materials and form that occur in the coastal area has been

developed. It is now possible to Dredict with a high level of' con-

fidence the probable effect of any major modification upon the environ-

ment. It is this prediction capability that permits the development

and selection of possible alternatives for the future use and management

of our resources.

The inherent values of the coastal zone are many and varied, and

it is the retention and development of these values that makes planning

essential. Economic values have been well-documented, and have become

evident in, for example, oil and mineral extraction industries, com-

mercial fisheries, and the trapping of fur animals. Major cities,

dependent upon connection to the Gulf and inland areas, have developed

at high land points or on the fringes of the wetland areas. Of no less

value, the coastal zone is a scenic, historic, and recreational source.

Other renewable resource values include storage of surface and ground

water, and wildlife habitats.

Early European settlers and more modern civilizations have

tended to make extensive and often wise use of land as they settled,

farmed, and developed the levee lands, and fished and hunted in the

wetlands. Road and water transportation have long played a major role

in development of the region and are essential components . In more

recent times, as man has tried to overcome the hazards of floods and

storms, and as extraction of subsurface minerals and use of other reso4rces

have become more pressing, the environmental base has come to show

signs of serious, perhaps irreversible stress. There is a real danger.
that many of the values traditionally cherished by the people alre bein.01,
threatened or lost through environmental and cultural pressures. This
requires a coastal zone management plan that achieves a compatible re-
lationship between the land base and the needs of the people, one

which will be mutually beneficial now and in the future.

In concept, such a plan must recognize the environmental. oppor-

tunities and constraints, as well as the need for man to make adapt-

ations of the environment for his successful use and occupation of the
land. But it should point out that man should use restraint in manipu-

lating the environment if it is to continue returning long-term values

to him, as a user and a steward of the land. This study has attempted

to arrive at such a plan for the south central area of the LouisLF.na

coastal zone.

Essential to successful management is the organization of

environmental data in a way that aids in the decision-making process.

To this end, the overall study approach included the following steps:

1. Define natural systems in the study area and identify

processes, forms, and materials which characterize the systems.

2. Inventory environmental and land use data for the study area;

determine natural and man-induced environmental succession;

and identify indices of change and quantify wherever possible.

3. Based on natural and man-made features, define management and

development areas.

4. Recommend future land use and management for each area, with

priorities for development and preservation.

5. Devise a surface water management plan compatible with

recommendations in Number 4.

6. Identify existing and proposed projects which conflict with

Numbers 4 and 5, and make recommendations for reducing im.-

pact of conflicting projects.

Environmental and Land-Use Atlas

Systematic consideration of spatial aspects of processes,

materials., and forms was accomplished by compiling data in atlas format.

Data were assembled on base maps at a scale of 1:250,000 and reduced for

presentation in the report. The atlas (Volume II) is not intended to be all-

inclusive@' rather,key geological, geographical, and ecological elements

and processes have been selected which weigh heavily in the planning

process. Each plate in the atlas is intended to be self-contained.

Additional sheets will be added in the future as funds, needs, and data

become available.

For example, soil conditions are clearly of primary importance

in determining land-use suitability in the Louisiana coastal area (Plate

8). Fortunately, soils have been systematically classified and mapped

throughout most of the study area. Their characteristics have been

defined and they have been evaluated from the standpoint of opportunities

and constraints related to specific uses (Fig.. 2-1). Further, the

distriblation of soils mirrors that of landforms. For these reasons, the

soils map has been included in the atlas.

The distribution of faults and salt domes (Platel4) was included

because they represent environmental constraints and opportunities.

Occurrence of mineral deposits is controlled to a large extent by

these structural features. They are important in determining founda-

tion stability. Salt domes may be of considerable importance in the

development of underground storage or waste treatment chambers.

The vegetation and oyster maps (Plates 9 andlO) show the distrib-

ution of important biological indicators. Involving sessile organisms,

they reflect specific ranges of ecological conditions. Certain organisms

are so selective that they become indices of a certain environmental

condition or habitat. Their distribution, in that case, defines the

extent. of the habitat and changes in their distribution through time

reflect changing ecological conditions. The distribution of oysters is

indicative of conditions of water chemistry, turbidity, temperatttre@ and

OLD DISTRIBUTARY LEVEE
BAYOU & DRAINED SWAMP BACKSWAMP
BEACH RIDGE BRACKISH MARSH NATURAL LEVEE$
SOILS FRESH MARSH & DRAINED MARSH BOTTOMLAND BATTURE
SALT MARSH LAKE, DAY, ON POND C
POND

L4
SOIL C ERCE
CYPREMORT SHARKEY- COMMERCE LOAMY
COITVE14T UNDRAINM DRAINED DRAINED SWAMP CYPREMORT ALLVVTAI,
FRESH FRESH/SALT MARSH SVAMP UNDRAINED SWAMP Tunica CONVENT
ASSOCIATION 11111111. 11L1;ATE1 SAND @ARSI- mhoon g.Ili.n WATER Baldwin convent-silty
MARSH baldwin sharkey MARSH Barbary mhoon Iberia convent-loamy
Iberia dundee unstable; organic Maurepas baldwin "11-1.1
silt loam
organic Uiver of various surface material several feet thin organic sur- clay surface silt loam stratIfteO
GENERAL thicknesses underlain by soft unstable orgaric material of varying silt clay thick underlain by organic face underlain by and subsoil surface; silt loam;
dispersed saline clays and loam Illy; lith spot, underlain
.u, k, el.y. with separation thicknesses underlain by silty clays subsoil silty clays with sep- material several thin of th ickat Ran ic below 25" by silt clay very fl-
"" '17'd'd@ P"" or _ck organic surface matelill; organic l-m@ flooded loam sub- to fine
SOIL I u rl"in face yer I to most of time; oil loamy.
underlain by a 11. btly firm to with separation when flooded. station when flooded: feet thick under- ade by :er I
'e '_"" i'l clovs and ao., cla y, with some veral feet thick loamy fi 11.
CHARACTERISTICS I h- ...... 1'. in, "i-d p-manently high water table black organic material 2-8' thick over lain by clay: I-several feet over firm semi-fluid
Permanently high -t- table thick p.,tio.., @1.-
it 1, h, I .' na@n t., -ft clav;.,ome llotation. some thin loamy loamy fill.
p- '--nt high
permanently high water table fill material. table

SUITABILITY
TOP 11011. not suitable not not -itable g-d-fair not suitable not suitable not suitable not suitable not suitable good-f.il fair
HIGHWAY SURCRADE not fair not suitable fair-poor not suitable not suitable not suitable not suitable not suitable fair-poor good-fair
HIGHWAY .91TBBASE not ..liable fair not -it.bl,, fair not suitable not suitable not suitable not suitable not suitable fair fair
RFSlt)FNTIAL FILL not suitable not suitable I suitable fair-poor not suitable not suitable not suitable not suitable not suitable f.ir-p..r fair
SAND OR SHELL (subsurface feature) not suitable good out suitable not suitable not suitable not suitable not suitable not suitable not suitable not suitable good-fair
DEGREE
OF LIMITATION
IIOMF..ITTF..q (i--, tory) verv severe sev-, ye- ever,, slight to moderate very severe severe slight to severe severe verv severe very severe slight to moderate

LIMITED INDUSTRY with verv severe severe v'r, -11- moderate to severe very severe severe slight to severe severe very severe severe moderate to severe
-nitv .-.age system
IANDSCAPF-4ARDENS-LAIN5 verv severe severe very evere slight to moderate very severe severe slight to severe severe very severe severe alight to moderate

PJAYGROUNDS-PICNTC ARrAe very a-cre severe ver, severe moderate to severe very severe severe slight to severe severe very severe severe moderate

STREF.TS-ROADS-AIRPORT RUWAYS very severe -vere moderate very severe severe slight to severe severe very severe severe moderate
CAMPS I TFS-COLF FAIRVAYS very severe severe .1vere SlirTIL to moderate very severe severe slight to severe severe verv severe severe @light to moderate
ENGINEERING
CHARACTERISTICS
potential h I gh high low highbillb very Shigh md I.. high w
hi 1". verv sa,derat,
rink-swell potential low to high none high Ill hi h high I
be-Ing at"ngth low - yet, low high 1- very low I.. low - very low ol low -d-ate
'tor'. ::ildlng' moderate
corro.,i-, potb t1al high high big[, high

DEER, DUCKS HARBOR FACILITIES
CRAITISH
DUCM; DUCKS DEER DUCKS DUCKS DEER DUCKS TURKEY, SOUIRRELS MARINE-TYPE INSTALLATIONS
MANAGEMENT DEER nFER DUCKS DEER CRA%'.TISH, RABBITS OUAIL DUCKS, -nHIRRELS
-.h.rc bird, RABBITS, DOVES, QUAIL

near sea level
p..rlv drained poorly drained near sea level near sea level poorly
flooding wet to maderatelv flooded poorly drained poorly drained dra:ned slightly wet
DRAINAGE FACTORS flooded - -line near sel level we t infrequent f oods
t idewater.

wildlife residential, livestock. on pasturetrange urban, industrial recreation, residential
wildlife habitat bird sanctuarv cultivated crops, stable areas Idlife habitat crops, urban, pasture.
EXISTING USEAGE recreation "rbdn..p,,,,tur,, sugarcane, urban weadl nd, being industrial, flood reten-
at 1.1 wildlife habitat cle: re tion . woodland, wildlife,
P
P

industrial cropland. pasture, borrow fill
urban. industrial
on of soil associations showing land-use suitabilities and limitations as associated with the natur-
Figure 2-1. Schematic cross-secti al
environments of the Barataria-Terrebonne area.

nutrient supply that are ideal for many important estuarine organisms.
Oyster distribution, then, becomes an index for prime estuarine conditions.

Since surveys of the distributions of organisms themselves are not

available, the lease files of commercial oyster beds of the Louisiana

Wild Life and Fisheries Commission become the next best source of data.

The transportation and oil and gas maps (Plates 17 and 15)

represent elements of land use that are particularly important in
considerations of environmental management. Highways, railroads, and

mineral industry access and pipeline canals often conflict with natural

circulation and runoff patterns. There are often a number of secondary

stresses associated with these activities.

Unique environments (Plate 13) shows the distribution of parks,

game management areas, archaeological sites, and streams designated by
the state legislature as scenic rivers and waterways. This map is useful
not only in evaluating the impact on these special places and features
in reference to proposed projects, but also reveals clusterings that

become important in considering future regional recreational needs.

Plates 4-7 and 11 deal with various aspects of hydrology and water
chemistry. The hurricane storm surge map (Platell) indicates tne extent
of floodin- and maximum wind velocities associated with Hurricane Betsy,
which struck the study area in September of 1965. Hurricane Betsy was
selected as a case study because it was a very severe storm whOSEt track
bisected the study area. The plate also shows the extent of high ground
and flood protection levees. The maps dealing with precipitation, pre-
cipitation excess, and salinity (Plates 4, 5, 6, 7 ) provide important
input in the development of a water management plan.

The canal map (Plate 16) can appropriately be described as an

impact map. It illustrates, in quantitative terms, the extent of canal

dredging in the study area.

Plates 18-22 summarize an approach to management of the area and

will be discussed at lenath in another section of this report.

Grid Cell Data Collection and Display

Several techniques have been formulated for handling quantitative

process and inventory data. These techniques relate primarily to cli-

matic and hydrologic data and to relative magnitude of man-induced hydro-

logic changes in the coastal zone. One form of output consists of

computer-printed contour maps the same scale and format as other process

and land-use maps in this atlas.

A data-cell concept has been utilized for organization and display.

The initial step in the system, data collection, was formulated by

settin- boundaries for the study area and subdividing the area into

data collection cells or units, based on the Louisiana Coordinate Sys-

tem - South zone (Plate 2). This vielded a total of 1562 square cells,

each being 10,000 feet on a side, and located by latitude and longitude.

Once established, the cells become the working units for collecting,

as well as organizing, reducing, and manipulating the environmental data.

One application of the data-cell system was in an inventory of

man-made water bodies. Basic data were derived from U.S. Geolcgical

Survey topographic maps at a scale of 1:24,000 (7 1/2-minute quadrangles,

various dates), controlled aerial photo mosaics (Amman International

Corporation, 1956) at the same scale and format, and uncontrolled

mosaics (U.S. Army Corps of Engineers, 1969). A transparent overlay

with cell boundaries was constructed for each of the 7 1/2-minute

quadrangles. Primary use categories were established for -man-made

waterways, including mineral industry access canals, rig cuts, major

pipelines, minor pipelines, lumbering canals, trapping cuts, borrow pits,

navigation canals, boat slips, and major and minor drainalge canals. The

waterway types were color coded and an overlay sheet updated to 1969

was prepared for each quadrangle. Using a map measuring wheel, Cie

waterways were then measured by type for each arid cell, the information

being tabulated on coded data sheets. A random sampling of widths by

type was taken from the entire area. Width measurements were made on the

aerial photo mosaics with the aid of a calibrated optical loupe. Samples

included water bodies in all soil types in order to take into account

variations introduced by bank instability. The areas of non-linear

man-made water bodies were measured by planimeter. All data were entered

onto computer cards,and a program was developed to calculate total area

for each water body type by cell. A companion program was develcped

for computer plotting of the values on atlas base maps. Plate 16

of the atlas shows contours of total canal density in the study area, as

well as tabulation of total canal areas by type.

'Hydrologic Models

To effectively manage the study area, it is necessary to analyze

direction and magnitude of fresh water flow. Although some types of

data are plentiful within the study area, there are serious gaps in

streamflow and topographic data. Records of streamflow are practically

nonexistent, and regular streamflow measuring stations would be very

costly to maintain because of the extremely low gradients. There is

no precise information on topography. The available topographic maps

show a minimum contour interval of five feet, but most of the area is

less than five feet above mean Gulf level, making it difficult to

estimate water surface slopes. At times, the direction of streamflow

is uncertain and it is difficult to distinguish on the map between

distributaries and tributaries.

The data availability and hydraulic characteristics of the region

dictate the method of treatment. Runoff has to be estimated from rain-

fall data, and the Thornthwaite-Mather water balance method (Thornth-

waite and Mather, 1955) was employed for this purpose. Subsequently,

two mathematical models, including a steady- and a transient-state model,

have been devised to simulate the runoff through the system (Light et

al., 1972). In developing the models, computerization was an absolute

necessity because of the large quantity of data to be handled and

tho large number of arithmetic operations. A grid-square technique
(Solomon and Denouvillez, 1968) was employed for efficient compater

storage and retrieval of data. A series of computer programs was

developed to reduce these data to proper form as input, execute the

operations of the two models, and display the results in tabular print-

outs and graphical or map plots.

The grid overlay, consisting of 10,000-foot square cells, was

utilized as a framework for data input to the models, each cell. being

assigned an index number. A total of 1602 cells were required to

cover the entire project area, and various meterological, phys.o.graphical,
and cultural data were compiled for each cell. The data pertinent

to this study, consisting of monthly rainfall amounts recorded for the

period 1945-70 and land-water ratios, were stored on magnetic tape.

The rainfall compilation by cell was obtained by first assembling tile

available records at 18 climatological stations in or near the area,

filling in the missing amounts by regression, and then interpolating

the complete 26-year set of values at the midpoint of each cell. The

orographic bias in rainfall is considered insignificant in the area of

interest, and a linear 3-station interpolation scheme was used. Land-

water ratios were obtained from 7 1/2--minute topographic quadrangles as

a measure of the relative proportion of land to total water surface area

of all water bodies within the cell, including bays, lakes, swamps,

marshes, and channels.

Runoff from land areas and fresh water accretions to water bodies

were determined by the Thornthwaite-Mather method based on a soil moisture

accounting procedure and on formulas relating moisture losses to rain-

fall amounts, air temperature, latitude, and season of the year. The

method assumes that water losses from water surfaces, both open and vege-

tation-covered, occur at the potential evapotranspiration rate. These

losses are generally greater than the total losses over land and can

result in moisture deficits during dry spells, particularly in summer

when potential evapotranspiration is high. Recharge computations depend

on the assumed saturation capacity of the soil. This capacity-is rated

at six inches within the project area, based on some measurements made

in the clay alluvial soil. Some confirmation of this capacity and the

general method was obtained by tests of runoff at a few gaged upland

basins outside of, but adjoining the project area.

The Thornthwaite-Mather procedure was programmed to compute the

separate land and water components of rainfall excess or deficit in

each cell from input of rainfall depth, air temperature, cell latitude,

and calendar date. The final step is in the application of the land

and water surface areas to the two components to obtain a weighted sum

representing the net runoff depth generated within each cell. All

the basic data were processed through this manner, resulting irt storage

of 312 monthly runoff values within each of 1602 cells. The dual compu-

tation method employed here is similar to that applied to the Lake Mara-

caibo basin in Venezuela (Carter, 1955).

Previous regression studies for the area showed a strong inverse

correlation between monthly averages of salinity at various measurement

sites in the area and monthly averages of fresh water input lagged one

to six months. Therefore, it was concluded that a model providing an
estimation of the geographic pattern of long-term streamflow averages

would be useful in defining the corresponding pattern of mean salinity.

Such a model, termed a steady-state model, was constructed to route the

runoff generated within each cell through the entire system of cells

(Light, et al., 1972). This model consists of a tracking pattern denot-

ing the estimated mean direction and percentage of flow exchange of

each cell with the four adjacent cells. This pattern is deduced from

examination of topographic maps and aerial photographic mosaics, taking

into account the stream configuration, widening or narrowing of the

streams along their courses, and the general seaward direction of

water travel. The model represents an idealized approximation to the

real system of channels, but should provide a reasonably good estimate

of streamflow crossing the cell boundary. Since the model is utilized

to predict averages for periods of several months or longer, storage and

dynamic factors are ignored.

A computer program was developed, utilizing the steady-state model,

to determine the mean geographical distribution of fresh water flow over

a study area consisting of the region north of the Intracoastal Water-

way. Input to this program consists, first, of the tracking pattern

translated into a series of coded statements defining the course of

flow between junctions. The second input is the series of monthly values

for each cell within the study area. The computer averages the depths

of runoff for the desired period of time, converts inches of depth to

average discharge for the period in cubic feet per second taking cell

area into account, and routes the discharge from cell to cell according to

the tracking pattern. Output is in the form of a printed table show-

ing routed discharge for each cell, and in the form of a contour map

showing isolines of discharge.

A transient-state model was devised to provide information on

short-term variations in streamflow and water surface elevations (Light

et al., 1972). The model, similar in several respects to those devel-

oped for the Mekong (Zanchetti, et al., 1970) and the Sacramento-San

Joaquin (Dudley, 1971) deltas, was applied to a 618-square mile test bas-

in consisting of the drainage area of the Bayou Chevreuil above Lake des

Allemands. This basin is located in the headwaters region of the project

area and is not subject to significant backwater from normal ocean tides.

The model incorporates storage and kinematic factors not present in the

steady-state model, and produces simulated stage and discharge hydro-

graphs of the rise resulting from heavy rains at selected points in the

watershed. As noted previously, no discharge observations are available

in the project area for checking purposes. However, there are continuous

records of river stage at several locations, and these can be used for

calibration and verification of the model.

The transient model involves subdivision of a watershed into a

number of zones based on tributary drainage boundaries, and determination

of certain physiographic data for each zone (Atlas, Platel9). These data

consist of a total area and total water surface area of each zone, the

combined width of all channels linking each pair of zones, and distances

between centers of mass of linked zones. The test basin, whose water

surfaces comprise 62 percent of the total drainage area, was divided into

26 zones.

The hydrologic inputs to the model consist of hourly values, of

zonal rainfall excess for selected study periods, obtained by analysis

of available short period rainfall records and the previously computed

monthly runoff amounts for the group of cells comprising the zone. Five

periods of heavy rain accompanied by major stream rises were selected for

study after examining the daily rainfall record for the past 20 years

and the corresponding daily stages recorded at the Chegby river station

on Bayou Chevreuil.

A computer program, based on a finite difference integration of

the equations of motion and continuity, was developed to execute the

computations of the transient model. Stream velocities are very low and

inertial forces can be safely ignored, thereby reducing the equation

of motion to the 'Manning formula involving factors of head, hydraulic

radius, cross-section area, and a friction coefficient. The time step

for the computations varies from one hour for the rising limb of the

hydrograph to six hours on the recession.

Total input to model consisted of the physiographic and rainfall

excess data noted previously, and certain initial and boundary condi-

tions. The latter consisted of the estimated water surface elevations

at each node prior to the rise and a fixed lake elevation at the outlet.

In addition, there are certain undetermined parameters that have to be

evaluated by a calibration procedure. These consist of a channel. friction

coefficient, cross-section form, low-water depth in the channel, a

storage reduction factor reflecting space occupied in the marshes by

submerged vegetation, and a runoff volume correction factor deduced

from ratios of areas underneath the two hydrographs.

Output of the model in its present form consist of a tabular

and graphical printout of the computed and observed stage hydrographs

at Chegby, and a table listing crest stages computed at all nodal

points in the model. Some tentative results have been achieved il.-i

attempting to obtain the best match of two hydrographs by a series of

trial-and-error runs. The optirqum shape of cross-section appears to

be the wide rectangular type as compared to the triangular or parabolic

type, the two other types tested.

As stated previously, once a model is developed and calibrated

it can be used as a simulator, either to produce historical extensions

of the record or to evaluate the effect of artificial changes in the

watershed. In the latter case, flows can be injected at one or more

points to simulate diversion of water from outside sources, or the rout-

ing scheme can be adjusted to conform with planned construction works

in the watershed. Such land or water management changes will affect

the stage, discharge, and storage characteristics of flood rises,

and may have both detrimental and beneficial aspects. As an exanple,

a simulator run was ipade on the January-March 1955 flood utilizing the

tentative calibration constants previously determined, but assuming a

hypothetical 50 percent uniform reduction in channel conveyance, a

reduction that might be produced by canal filling. The "before and

after" hydrographs indicate that the change would result in a substantial

reduction in peak discharge and an increase in water retention at the

expense of a slight rise of the flood crest at Chegby. However, com-

puter results for upstream points indicate more substantial increases in

stage at those points, and therefore, that a significant increase in

flooded area would result from the alteration of the canal system.

Present results of the transient model are preliminary and

only cover a portion of the project area. It is expected that the model

will undergo changes and that there will be refinements in data processing

techniques as the work proceeds. The greatest advance would probably

come from the introduction of field observations in place of the present

assumptions of hydraulic characteristics of the channel network. It

is hoped that these observations will be forthcoming in the near :@uture,

and will permit closer correspondence between model and prototype.

Use of Remote Sensing Imagery
Conventional aerial photography and remote sensing imagery provided
invaluable primary sources of data for the study. As previously mentioned,
aerial photo mosaics were used for measurements of man-made water bodies
and construction of a number of the atlas maps. In addition, a number
of remote sensing missions by the National Aeronautics and Space Admin-
istration have been flown over the entire area and selected parts in
recent years. A list of the more important missions is presented in

Appendix A.

Of particular value was the imagery acquired during the March,

1972,high altitude overflight. This data provided major input into the

overall evaluation of the coastal environment as well as evaluation of

specific parameters. It substantially enhanced knowledge concerning the

distribution of vegetative communities (Plate 9) and circulation patterns

in the bays and coastal waters, as revealed by turbidity contrasts, and

allowed updating information on shoreline changes along the barrier islands

(Plate 12).

Even though much of the vegetation was dormant because of the winter

season, inspection of the imagery allowed differentiation of at least

four distinct categories corresponding to cypress-gum swamps, marsh,

flotant marsh, and mangroves. Directly related to this differentiation,

the imagery aided in delineating the topographic effect of natural levees

and crevasse splays.

Contrasts between clear and turbid waters allowed general inferences

to be made as to patterns of water movement in the bays and adjacent coast-

al waters. In particular, the extent, direction, and color density of

plumes showing effluent from bays into the Gulf of Mexico revealed distinct

patterns of coastal circulation.

With regard to the barrier island system, the imagery not only allow-

ed an updating of shoreline changes, but also provided valuable information

as to the occurrence and extent of tidal deltas and the relative magnitude

of tidal flow through the tidal inlets between the barrier islands. Both

are critical factors governing continuity of longshore sediment drift.

The imagery was invaluable in delineating present land use patterns.

The March, 1972, high altitude coverage of the Louisiana coastal

zone should be regarded as one of the area's most important his-

toric documents. This type of synoptic regional coverage is so impor-

tant that it should be repeated at least once every two years.

User Input

User input is an indispensable ingredient in the planning process.

Ideally, the procedure for obtaining user input should be formalized so

that all interested parties have an opportunity to present their view-

points. Since the study group did not have the authority to conduct

public hearings, the necessary input was obtained by seeking out interested

parties and agencies. As a result, a major part of the study effort

was devoted to personal interviews, attendance of public hearings,

participations in meetings (planning meetings, symposia, and workshops)

and presentation of lectures to special interest groups.. During the

course of the project, direct contact was made with a broad spectrum of

local, state and public agencies, representatives of industry, agriculture,

landowners, and private citizens. During the last six months of the study,

illustrated lectures explaining the project methodology and tentative

results were presented publicly to a number of groups for comment and

discussion. An attempt was made to consider all criticism and suggestions.

A list of primary contacts is included in Appendix B

NATURAL SETTING

Evolution

The Barataria-Terrebonne region is part of the Mississippi deltaic
plain. Its geologic history relates a sequence of delta building and

abandonment under a condition of continuing subsidence. With regard to

its present surface configuration, building of the area started ap-

proximately 3500 years ago with development of the Lafourche delta com-

plex joining and partly overlapping the relict margin of a deteriorated

Teche delta to the west (Figures 3-1 and 3-2). Growth of the Lafourche

delta was sustained for some 2000 years. Then the Lafourche course was

gradually abandoned in favor of the present Mississippi channel. A

diversion of the main channel near Donaldsonville about 1500 years ago
directed increasing amounts of sediment eastward, resulting in the

Plaquemines-Modern delta complex.

This dual nature of the deltaic sequence is reflected by the present-
day landscape. The area displays two major subsystems. These are:
1) the abandoned delta complex of Bayou Lafourche, the Terrebonne region,
and 2) the basin confined between the Lafourche complex and the active
channel-levee system of the modern Mississippi, the Barataria region.
Both systems include an arcuate chain of barrier islands along their

Gulfward margins.

The Terrebonne Subsystem

The deltaic landscape of the Terrebonne region is dominated by a

maze of natural levees that flank the abandoned distributary channels of

the Lafourche-Mississippi. The ridges and channels fan out from the

cities of Thibodaux and Houma, where the main Lafourche channel branched

19DEX iAAP

NA
ALLUVIAL

TEXAS MLAIN

TECHE:
1, 2,4 3o.
ST. BERNARD: 3, 5, 7,8, 9, 11
8
LAFOURCHE:6, 10, 12, 14, 15
PLAQUEMINES-MODERN: 13, 16
3
7'
71"'N :N
6
J. 5 o,
O'N
I-n --------- 4 1@4# R S

7.,

2 o 14 -
10
9
YN
ES"'

16 1

0 r
14
-', "I"DE _@AP
X

ANA

TEXAS

0
3'yr
+ *4 *01GOIj JA + + +
DELTA COMPLEX 90.
SCALE IN MILES
Figure 3-1. Delta lobcs fcrmed by the Mississippi River during the past 6,000 years. (After Frazier, 1967).

THOUSANDS OF YEARS BEFORE PRESENT

00 01

PLAQUEMINES-
MODERN
DELTA COMPLEX
MISSISSIPPI RIVER

BAYOU LAFOURCHE

BAYOUS LAFOURCHE AND TERREBONNE

LAFOURCHE
BAYOU BLACK DELTA
COMPLEX

BAYOU BLUE

BAYOU TERREBONNE

BAYOU SAUVAGE
(71

MISSISSIPPI-LA LOUTRE ST. BERNARD
I DELTA
BAYOU DES FAMILIES COMPLEX

1-n BAYOU TERRE AUX BOEUFS

MISSISSI
11
P I RIVER AND BA YOU LAFOURCHE

BAYOU CYPREMORT

NJ BAYOU SALE TECHE
DELTA COMPLEX

BAYOU TECHE

MARINGOUIN
DELTA COMPLEX
P
D@
9@URIHE

"IISSI'SIP
BA1'

Fi-ure 3-2. Chronology of delta lobes as determined by radiocarbon dating of deltaic plain peat deposits.
0
(After Frazier, 1967).

into smaller distributaries. These locations were equivalent to the

present day Head of Passes of the Mississippi. Bayou Lafourche repre-

sents the youngest of the major distributaries active at one time.

Earlier building stages of the Lafourche delta complex involved, Successive-
ly,establishment of the Bayou Terrebonne course and reoccupation of the

Bayou Black channel, originally a distributary of the Teche delta complex.
The natural levee ridges form a skeletal framework of positive topo-

graphic elements. Established during delta progradation and further
builtup by sediment deposited during overbank flow, the levees Eire a

tribute to the fact that at one time rates of deposition exceeded the

combined effects of subsidence and erosion. The natural levees vary in

height and width according to original size and amount of subsidence.

Original size relates to one time importance of the associated channel as

a distributary and the time period this channel remained active. Vari-

ation in the amount of subsidence is a function of age and a general

Gulfward increase in subsidence rates due to seaward downwarping (Fisk,
1956). In general, the distributary levees attain higher elevations and

greater widths upstream. Levees flanking Bayou Lafourche are the most

prominent, with crest elevations of as much as 15 feet in the vicinity

of Thibodaux. Though sloping gradually seaward and becoming ever narrow-

er, they stand out as a natural corridor that traverses the full width

of the coastal zone.

Lying between natural levee ridges are large interdistributary

basins, occupied by extensive swamps, marshes, lakes, and bays. Inland,
the basins are frequently enclosed as a result of overlapping of dis-

tributary subsystems. Toward the coast, the basins generally widen and

are open in a seaward direction. Established as shallow water bodies

between extending levees, these basins gradually filled as the delta

prograded. Initial filling resulted mainly from an influx of inorganic

fine sediments carried into the basins during overbank flow and cre-

vassing of the flanking distributaries. Eventually, however, the basin

floor was raised to the extent that colonization by marsh plants could

occur. From that time on, organic accumulation became increasingly

important. With subsidence continuing, thi s accumulation, where dominant

over the introduction of inorganic sediments, resulted in development of

thick peat beds. Peat beds attain large thickness,particularly in the

inland basins where the progradational and aggradational sequence allows

establishment of cypress-gum swamps. These swamps were able to persist

until present time through a rate of peat accumulation that offset sur-

face subsidence.

The Barataria Subsystem

The Barataria region may be considered the counterpart of the

Terrebonne region. In essence, it represents an inter-levee basin, but

rather than being confined between levees of the same distributary system,

the Barataria basin lies between the main levees of successive delta

complexes. Therefore, it should be considered on the same time and areal

scale used to measure development of a delta complex.

The Barataria basin shows the converging influences of both La-

fourche and Modern Mississippi delta building processes. Overbank flow

and crevassing from both systems have contributed to aggradation of the

basin. Natural levees associated with crevasse and terminal distributaries

extend into the area from both margins. Basin filling was dependent on

the extent to which lateral influxes of sediment merged along the basin

axis. Through most of the basin, deposition of inorganic sediments allow-

ed a swamp and marsh succession. Greatly enhanced by accumulat-@on of or-

ganic debris, aggradation has raised and maintained surface levels at

about high tide Gulf level. The degree to which organic accumulation con-

tributed to this is manifest in extensive peat beds that reach thicknesses

of 20 feet or more in the upper basin.

Environmental Differentiation

The major physiographic elements, such as natural levees and inter-

levee basins, provide an environmental differentiation that is reflected

in the distributions of soil and vegetation types (Plates 8 and 9). Both

are largely a function of elevation differences and water levels, and of

topographic control over fresh water dispersion and salt water intrusion.

For both soils and vegetation, two gradients can be recognized, resulting

from combined affects of salinity and elevation differences. One gradient

is directed from the natural levees into the basins with elevation the

primary, and salinity the secondary control. A second gradient. is direct-

ed from the coast inland, and primarily reflects the decrease in open

water salinities in that direction. From the levees into the basins this

produces a gradation from relatively well-drained to silty soils and

levee forest habitats, to poorly-drained, highly organic clays and either

swamp or marsh habitat, depending on salinities. Major vegetative transi-

tions are shown in the transects of Figures 3-3 and 3-4. Detailed

schematics of vegetation zones and corresponding fauna are shoim in Figures

3-5 and 3-6.

AV
4%1

Figure 3-3. Transect showing transition from natural levee
oak forest to cypress-gum swamp, to fresh water marsh,
(Penfound and Hathaway, 1938).

Figure 3-4. Transect showing transition from natural levee
oak forest to brackish marsh through a shrub and cane zone,
L

(Penfound and Hathaway, 1938).

LEYEE
OLD DISTRIBUTARY DRAINED
U
TYPICAL BRACKISH MARSH BAYO LEL $.AMP AC--A-1
BEACH RIDGE NATURAL VEES
SALT MARSH LAKE, BAY. OR FRESH MARSH & sCITTCOAL."D BATTURE
Ds
FLORA POND MARSH
"(

.. ........ I. ..... 0" @Ypr...
--l- ,-1 g. -S.11:111
P- ii- iSd Pipl,
... k l,Y .....
kb.,i, hL-Y
h-b
.pp ....
TREES
ON SPOIL ILL- .. .....

Ilk
k
"-:kbyb-'k ..k
h -y 1--t

-h p-...
--h ld.,
@ld b..... b-@,
b-ill.

I-ih-i. ,Id-b - b11:111,11
I 'd
h I-1
_1d
SHRUBS b=h 2-h:bi: ON NTDDEIS1OLD'-CI- P.1-. "l-,
bl-b-,

VINES .11, C-- ild P.I.- i,Y i@y -- -Y

b ......p b=-d-
ILI- -1,

.Y
-d -i, -:2-d -Y.,
HERBS
Ilt ...
-M -1

............ ...
-d ........d
d- p-i-h
pik-ih
P-n-,

A QUATICS
hill lily

lly

-c-

@hi '1,i'k'=
ALGAE lh@
Ij

OLD DISTRINUTANY LEVER
DRAINED SWAMP
BRACKISH MARSH BAYOU A BACKSWAMP
TYPICAL &EACH RIDGE NATURAL LEVEES DRAINED MARSH
BOTTOMLAND
FRESH MARSH
LAKE, SAY, OR WTUNE
SALT MARSH POND POND
FAUNA
.4'

bacteria, fungi
MICRO- mei fauna bacteria bacteria bacteria' bacteria bacteria
p lychaete. -I. fauna zooplankt so pl nkton zooplankto. bacteria bacteria bacteria b
melofauna :cteria
-Zhipods proto- p.lychaetes polychaet:n. -I Isune ami.f.una miofauna meiofauna Mi0fauna rthworms
ORGANISMS protoza smiofauna oligochaetes mei.fauna

fiddler crabs Dona (bivalve) smile
MOLLUSKS mud crabs gho.xt crab. - crabs Lyster snails
-.sale burrowing brimp clame rh clam crayfish crayfish lend snails snaill land
.nail. i..pod. hr !-. shrimp -.eel. mussels cr yfh bnails
- el crabs cl.- Is- -:eel. Pill ug
CRUSTACEANS Y:tet. cla..

alligators frog. tree frog tree frogs
AMPHIBIANS & alligators alligators turtles water stakes toads bullfrog. toad.
salt marsh water snake water stakes trt lea snakes
salamanders salamanders salmand..q leopard frogs salamanders
REPTILES frog. all ig.t.r. water snake. snake.

be, anchovies m'- minnows
.i,wer.ide (gamb"ia) (ganbusia)
killifi.h killifish menhaden perch perch
crap crapie typi :1 fre.,h water
FISH sea cat fish ':h fi.hc asabl ge
mullet catfi catfish.
many others gar. gar
bas bass

herons, egrets
ibl.
rails shore birds ading bird. d ducks duck. warblers
k ducks uck' 9
sparrows. wrens gull. - d, ding birds -din bird. -ding birds v&dLn birds vadin birds wadIn birds virmos
BIRDS blackbirds terns * upcarr-. gulls fieldbirds fieldbgird. fieldbird. hawks hawk. hawksg hawks
gtackles r.IIs t:rn:_. blackbirds blackbirds blackbirds typical terrestrial birds
plovers, Eandpipers p Ii

bear
r:cco- raccoon armadillo opo am
re coon raccoon raccoon raccoon raccoon d opossum r
krat muskrat porpoise _:r., de r raccoon bbit
raccoons* muskrat muskrat d er a weasel r:cc I
MAMMALS nutria nutria nutria nutria rabbit opossum opos un r bbit dee
.I.k mink otter deer deer rats-mice rabbit rabbit Zer weasel
otter otter mink skunk skunk weasel nutria
nutria

-.p
ants ant.
gr ashoppers hippers
I, gr:;1
_:qu to itoes
INSECTS deer M all transients flieu chirono.id larvae flymenopt:ra.) Or hoperts Diptere Remiptera Odonsta Homptera
many fl!-.e gnat: (wasps nt (grtas hoppers) (mosquitoes, flies, goats) (water Insects) (dragonflies) (leafhoppers)
dragonflies
we p star insects
.4

leafhoppers

Figure 3-6. Schematic cross-section of fauna as related to the natural environments of the Barataria-Terreboyme area.

From the coast inland, the soil and vegetation gradients are most

apparent in the basins. Here one finds a transition from salt water

marshes through brackish, intermediate, and fresh water marshes, to the

cypress-gum swamps of the upper basins. Both marsh and swamp soils are

highly organic, but organic content tends to increase towards the fresh

water environment (Chabreck, 1970).

The saline to brackish marsh, which borders on the coastal zone,

is firm and solid, but brackish to fresh marshes immediately inland

appear to be highly unstable, with topsoil of more than 80% organic

content.

The fresh floating marsh is probably the most unstable among marshes,

since, as a result of compaction and subsidence, the marsh root mat has

become separated from the substrate. Separation may be as much as

thirty feet. The space between the rootmat and the substrate is generally

filled by organic ooze or muck. This makes the area of floating marsh

highly vulnerable because marsh destruction will lead to open water

bodies that are too deep for an intermediate plant succession.

In the combined Barataria-Terrebonne area, the marshes are the major

vegetative cover. They occupy 63% of the area, or slightly over one

million acres (Chabreck, 1972). Size of the areas occupied by vegetative

types, that is, saline, brackish, intermediate, and fresh marshes,

are presented in Table 3-1. On Plate 9, the floating marshes are not

differentiated. However, they are extensive and cover approxinately one

quarter million acres of the Barataria-Terrebonne area (O'Neil, 1949).

Figure 3-7 shows their distribution.

TABLE 3-1.

Plant Species Composition, Average soil-Water, Salinity, and I
Acreage of Marsh Zones within the Barataria-Terrebonne Wetlands

Plant Species Marsh Zones Total marsh
Saline Brackish Intermediate Fresh
Bacopa monnieri (waterhyssop) 13.84 3.48
Distichlis spicata (salt grass) 10.85 21.0.2 7.96
Eleocharis sp. (spike rush) 15.17 3.79

Juncus roemerianus (black rush) 9.29 2.32

Panicum. hemitomon (maiden cane) 41.76 10.44

Pluchea camphorata (camphorweed) 9.95 2.48

Sagittaria falcata (bulltongue) 3.13 12.50 3.90
Spartina alterniflora (oyster grass) 65.26 16.31
Spartina patens (wire grass) 54.61 38.11 23.18

Total 85.40 75.63 65.03 69.43 73.86

Average Soil/Water Salinity in ppt. 17 9 5 1

Total Acreage in thousands of acres 328 261 58 405 1052

Data derived for Hydrologic Units IV and V (Plate 9 from Chabreck,
1972. Plant species composition of marsh zones is expressed in percent
frequency.

I ElE
?
T

LAC
NIP-ONVILLE
DE@
G AND LLEmAND
LAKE FF
A-
I -/
D
SIX MILE LAKK ILAE ILIKE LAKE
SALVADOR
.-REHE
TE -..E

cl,

A Tc

T
cl-T L A
E-111

LAKE
LIKE
-LLAKE
5Q-
e
I 1,.6ALlEIl,
A
0

CA" L
LAKE P'ELTo
1-AL

D 1 0 F

Figure 3-7. Distribution of flotant (After O'Neil, 1949).

Barrier Islands

The barrier islands are an integral part of the deltaic system.

Although initial development of the islands is not fully understood, they

can be placed in a general framework of delta building and abandonment

(Russell, 1948; Fisk, 1955; Kwon, 1969). During active progradation of

a delta lobe, fluvially transported sands are deposited in the immediate

vicinity of the distributary mouths, where current velocities are reduced.

These sands are subsequently redistributed along the delta margin, and

depending on quantities available and the wave and current regime, they

may become apparent as delta marginal beaches, spits, and beach ridge

complexes. As the delta lobe is abandoned and submergence of the delta-

ic surface is initiated as a result of subsidence, the sand deposits tend

to remain as a series of barrier beaches or barrier islands, separated

from the retreating delta shoreline by a shallow sound or estuary. As

subsidence continues, the barrier sediments become increasingly subject

to redistribution, resulting in an inland migration of the islands. This

migration is generally coupled with a loss of sediment, and consequently,

with a decrease in size of the individual islands.

The chain of barrier islands fringing the Barataria-Terrebonne region

relates to subsequent progradation and abandonment of at least two

Lafourche-Mississippi delta lobes, and possibly to a distributary system

associated with the Plaquemines-Modern complex. Two barrier chains can

be identified. These are 1) the Isles Dernieres chain, which includes

the Isles Dernieres proper as well as Caillou Island, Brush Island, and

Casse Tete Island further to the east, and 2) the Timbalier-Grand Isle

chain extending to the east and west of the massive Caminada beach ridge

complex near the mouth of Bayou Lafourche, and including the Timbalier

Islands, Grand Isle, and the Grand Terre Islands.

Development of the Isles Dernieres chain relates to the attenuation

of a subdelta that was associated with Lafourche-Mississippi distributaries

branching out from Houma; e.g., Bayou Petit Caillou and Bayou Terrebonne,

The Timbalier-Grand Isle chain, as well as the associated beach ridge

complex, relates to a subsequent phase of delta building and abandonment

corresponding to the history of Bayou Lafourche as a major Mississippi dis-

tributary. Sequential nature of development of the two barrier arcs is

apparent in the partial envelopment of the Isles Dernieres chain by the

Timbalier-Grand Isle arc.

Development of the greater Terrebonne estuary as an integrated bay

complex, and the concurrent migration and modification of the Isles

Dernieres barrier arc, as well as the western wing of the Timbalier-

Grand Isle arc are shown in Figure 3-8. The one hundred year sequence

shows gradual coalescence of Terrebonne and Timbalier Bays,which were

initially separated by the Bayou Terrebonne levee complex. A similar

sequence can be visualized for Barataria and Caminada Baysin relation

to the distributary complex of Bayou Lafourche.

Subsurface Characteristics

Of major consequence concerning development and management. of the

area under consideration are the characteristics of the vertical column.

For instance, where a natural levee has subsided, in part or totally below

the marsh surface, a firm substrate may be found at small depths. In

particular, the distribution of sands in the coastal area is important.

Sand bodies may provide supplementary sediment for process management or

stable surfaces for necessary development.

4
miles

nVI

66LF OF WXVO
ISLES DERMERES

miles

Op
FOO
_,@SL t, 'lop
1 0
I'k3k GMF CF MFX)W

Figure 3-8. Shoreline changes of delta margin islands in the abandoned
Lafourche Delta System, 1890-1960. (After Peyronnin, 1965.)

Figure 3-9 illustrates the subsurface conditions of the early

Lafourche delta along a profile from Houma to Terrebonne Bay. The

layer of organic matter or peat on top of the section, which constitutes

highly unstable deltaic or marsh surface, is essentially continuous and

gradually thickens toward the coast. On the other hand, the underlying

soft organic clays increase in depth inland. Sequence of deposition

in this area is not well known, but the lower peat layer probably repre-

sents the subsided margh surface of one of the older Mississippi River

subdeltas buried by a subsequent wave of alluviation as the early La-

fourche delta advanced into the area.

Figure 3-10 shows a sedimentary profile in a floating marsh of

Barataria Bay basin. According to the profile, a natural levee has

subsided below marsh surface, and the sediments composing the natural

levee, together with "soft, organic clay," appear to represent the former

active flood plain surface. The upper vegetative mat floats on a marsh

ooze that reaches a thickness of eleven feet. Organic content of this

type of marsh is typically high, usually greater than 50 percent (Kolb

and van Lopik, 1959).

Figure 3-11, after Fisk (1955), illustrates a simple depositional

sequence in the area of lower Bayou Lafourche. The sandy materials are

carried down to the mouths of former active distributaries in this area

and distributed around the delta fronts by waves and longshore currents.

The delta front sheet sands rest upon massive prodelta silty clays, and

grade upward into gray and black organic-rich marsh deposits. The

sheet sands occur at or near the surface around the mouths of Bayous

Lafourche and Moreau, and are present at progressively greater

4
0 TERREBONNE

9 C4 LAKE
0 40& GEPO BAK
2
LAR 15 BAYOU 9 31
17 26 27
24
SCALE
OU 0 2 3 4 -LES 21

0
13 2
0 a 9 10 11 12 13 16 17 Is 19 20 23 @4- 25 26 27 29 30 3
%
V. M F- R ......
SAN 0 / " @.K.".: . X.V ..........
AA 0 F-r 07 c c X..
0 -10

S I L-r Y

@z 20
BEDDED1 SAIN D
z
0 %%
%
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W .........
-
30
30

A . .......
-OR(BANIC CL^Y ^.N D PEA-r

-40
//4//

-50
10 20 30 40 50 60 70 80 90 100 110 120 130 140 ISO
DISTANCE IN THOUSANDS OF FEET
Figure 3-9. Profile showing buried marsh layer along proposed Houma Ship Channel. (After Kolb and
Vary Lopik, 1959).

j E F F- -6 R S 0 N A R 1 3 H

SCAL19

L(rrLE LAKE
TURTLE
BAY

A
0 5--
Roo-r Z.ONE:

A -r ORGANIC OOZF-
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sop -r ORGANIC L- AY

w ZO -
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30 - or

-AY
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0001,
40-/
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Figure 3-10. Typical section in floating marsh or flotant about 22 miles
south of New Orleans. (After Kolb and Van Lopik, 1959).

OSE DELTA-FRONT SHEET SANDS

EASTERN SU80ELrA
LAFOURCHE-MiSSISSIPPI 0ELTA

LITTLE LAKE SHEET SANDS
E3
BAYOU$ OCCUPYING ABANDONED LAFOUR04E DIS.
TRIBUTARY CHANNELS

TRACES OF ABANDONED LAVOURCHE 015TI"BUTARIES
v
(NOT OCCUPIED BY STREAMS)
0
BAR RIDGES IN MARSHLANDS
It r '
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BARATARIA BAY

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CAMINADA 5.1
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TIMBALIER SAY ..... 60

0 3 6

MILES
B'
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7
71
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WIDTH OF D15TRIBUTARY CHANNEL FILL 25
GENERALIZED -,MARSH 11AY SILTS &CLAY -7@

FACIE5 SYMBOL IDENTICAL ON SECTIONS
5 D 7-
7 so -
77 M
75 DELTA-FRONT SHEET S D 75
0 2 3
TNGS
7
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::MARSH& BAY SILTS& CLAYSL-
2s 7.
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J@
X
so
D
L-.-T A C.
E -FRONT IIIEET' :SANDS
RODELTA SILTY CLAYS tf,",
75
q.
W.-

Figure 3-11. Geomorphic features and sedimentary deposits in the
abandoned Lafourche Delta Complex. Black dots indicate location of
oyster reefs. (After Fisk, 1955).

depths inland. These sands lie forty feet beneath the delta plain

marsh near the head of the Lafourche distributary system. The thickness

of marsh deposits is indicative of the amount of regional subsidence

and compaction that has taken place while delta surface deposition was

progressing, gnd subsequently, as the marsh sediments have accumulated.

The upper surface of the sheet sands at its seaward margin can be

seen in the series of beach ridges in the marshes surrounding the distal

ends of Bayous Lafourche and Moreau. These ridges have sunk almost to

sea level, but their development was contemporaneous with the final

stages of seaward lengthening of the bayou courses.

The occurrence of the sheet sands at or near the deltaic surface

in the lower reach of Bayou Lafourche and increasing thickness of or-

ganic-rich marsh deposits inland explain the firmer nature of land toward

the seaward margin of this abandoned delta. They also partly explain

the reason why the higher rates of land loss occur inland,, although actual

rate of compaction and regional subsidence is greater Gulfward.

Natural Deterioration and the Delta Cycle

When examining a detailed map of the Barataria-Terrebonne region

one notices immediately that conditions at present are far from those

associated with an actively prograding and aggrading delta system.

The sea has made inroads into both the Lafourche delta and the Barataria

basin so that both function now as large estuaries. This condition re-

presents a phase of modification associated with abandonment and by-

passing of the area by the main stream of fresh water and sediment.

For the Terrebonne region this condition was initiated when the Missis-

sippi River abandoned its Lafourche course in favor of the present

channel. For the Barataria region,it followed when the Plaquemine-

modern complex extended rapidly seaward to the edge of the continental

shelf.

In a natural setting, abandonment and bypassing of deltaic sub-

systems is an,inherent part of the deltaic sequence, as is the subsequent

disintegration. When a delta complex is deprived of most of the previous

sediment influx, seaward progradation will give way to shoreline retreat

under the influence of wave action and subsidence. Marine ingression

is commensurate and partial drowning of the interdistributary basins

produces a hierarchy of bays. The bays are initially confined by

the skeletal framework of natural levee ridges. This condition is

well illustrated by the greater Terrebonne Bay and along the margins of

the Barataria Basin. Both estuaries show a highly irregular shoreline

representing a land-water interface whose length is many times that

expected from size of the water bodies. The length of interface,

together with the areal land-water ratio are major factors in determining

biological productivity of the estuaries.

An important factor in the beneficial development of crenulate

bay shorelines is the degree to which the shores are protected from

wave erosion. Although levee and basin deposits differ in sediment

composition and resistence to wave erosion, under the low energy wave

regime of the present estuaries, shoreline configuration is largely a

function of elevation. Subjected to subsidence, the higher levee ridges

escape submergence longer than the low surface of-the interdistributary
basins. Hence, development of the estuary as an integrated bay system

is allowed for as long as levee ridges extending into the estuary can

resist wave erosion; a condition that related to the presence of a barrier

island chain sheltering the estuaries from the higher energy wave regime

of the open Gulf.

There are three major natural processes that account for wetland

deterioration: 1) drowning of the marsh due to subsidence, 2) shore

erosion of lakes and bays, and 3) new marsh opening. These may occur

individually or concurrently.

Subsidence

The areas of maximum land loss are the areas of maximum subsidence,

a fact that is documented in the historic maps of coastal Louisiana.

When the filling in of the interdistributary basins by mineral or

organic sediments and vegetation growth keeps up with subsidence, for

instance, as in the fresh floating marsh, the marshes can overcome

subsidence. However, there many examples of areas where subsidence

occurs too rapidly for the marshes to sustain themselves. According to

Figure 3-12, there was the remnant of early Lafourche delta in the pre-

sent area of Terrebonne Bay until after the middle of the last century.

Since then, the delta lobe disappeared completely, with only relict

channels traceable in the rim of the upper bay.

Deterioration or subsidence of this subdelta lobe has possibly

undergone two stages of acceleration and deceleration. It is believed

that land deterioration was very slow during the gradual reduction of

water discharge through the subdelta system, and for some time after

the abandonment. The rate of subsidence could be constant throughout

the time, but before massive delta deterioration was initiated, land

loss should have been restrained by the protection of high and firm

saline marshes and sandy foundations around the delta front. When the

Terrebonne Brush I Tote L'
C@O
Bay

Timbalier Bay
Caillou 1.
Wine 1.
t 0, 0 5 IOMILES
efoleve 6.1 . I- 1 1
11845 Is 0 O/ier 1.

I eTe I. ea

Wine 1. Brush L

Olrnlere Caill Ou 1. 0 3 10 MILES
1887 1 1 1
r

Q::, CA

V,
Terrebonne Coss Tete L
Bay 0
B
s h
ru I
@4 13 a
@ lier

ne
E. Timbolier
lier 0 J 10 MILES
'Ll 947 Ifles DerWe"s

Figure 3-12. Shoreline changes in the abandoned Lafourche Delta
complex, 1845-1947. (After Kwon, 1969).

protective barrier was removed by further subsidence and coastal. retreat,

the low and vulnerable inland marshes with high organic soil content

were exposed to high waves from the Gulf of Mexico and intrusion of

salt water. If the protective barrier did not disappear, but continued

to exist in the form of barrier islands like Isles Dernieres and Tim-

balier Island, submergence of the marsh surface was initiated in low

places behind the barrier, but the net effect of Gulf water intrusion

should be the same. A slight subsidence could drown extensively the

low inland marshes, if vegetation growth cannot keep up with the sub-

sidence. It should be noted that the vegetation that maintains the

floating marshes consists predominantly of fresh water species. In the

above manner, marsh or delta deterioration may reach a stage of accel-

eration. However, when the encroachment of the bay reached the present

upper Terrebonne Bay, the deterioration decelerated. Land loss calcu-

altions show a very low rate of loss in this area, much lower than the

surrounding areas.

Levee flank depressions (Russell, 1936) are sites of rapid sub-

sidence and opening-up of marshes. These depressions develop just out-

side of the natural levee backslope along the main river channel.

They originate because natural levees composed of silty materials are

more dense than the surrounding marsh, and their weight tends to compact

sediments beneath them. This causes the levee to subside faster than

the marsh. The depressions created in a sag formed by the weight of

the natural levees become the sites of elongate lakes parallel to and

just marshward of the crest of the controlling levee. Bay Lucfen

provides an excellent example of a levee flank depression lake along

Terrebonne Bayou (Fig. 3-13). These lakes expand at the expense of the

Figure 3-13. Marsh deterioration as a result of subsidence. The
bays and lakes in the photographs have highly irregular shoreline
patterns which is one of the characteristics in areas where sub-
sidence is dominant over wave erosion as a cause of marsh break-up.
Bay Lucien and Bay la Fleur are examples of levee-flank depression
lakes (A). The depressions originate where subsidence of the nat-
ural levee is more rapid than subsidence of the marsh in the adja-
cent interlevee basin (B). Retreat of the shore line from 1952 to
1969 is readily apparent at point C. A decreased land-water ratio
has further resulted from the dredging of additional canals and
a widening of Terrebonne Bayou.

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natural levee and marsh, and in an advanced stage, the lakes Join with

those of interdistributary basins. This process throws light on the

development of numerous lakes and encroachment of bays toward the back-

slope of natural levees of the Mississippi River below New Orleans.

The linear lakes between beach ridges around the mouth of Bayou

Lafourche directly result from subsidence (Fig. 3-14). In all cases,

the lakes or bayous overwhelmingly dominated by subsidence have slightly

irregular outlines. Marshes drown below water level before wave action

starts to smooth the shores. Irregular outlines reflect local conditions

of soils, vegetation, etc.

Marsh Opening

Frequently, drastic land loss occurs through marsh openings which

are not directly related to subsidence. Such marsh deterioration happens

as a result of 1) marsh fires, 2) animal eat-outs, and 3) storms. Depth

of water in such openings may be only slightly more than one foot and

the bottoms are often covered with fine ooze that overlies the original

peat or organic clays of the underlying marsh (Kolb and van Lopik, 1959).

Marsh fires often happen during dry seasons. They sometimes occur

naturally, but are usually deliberately set as an accepted form of

marsh management. However, in extremely dry periods, when the water

table drops significantly below the marsh surface, the fires may burn

into the peat layer and thus create small lakes.

An eat-out describes a condition that occurs in the marshes when

muskrats or nutria become overpopulated and eat all of the stalks and

leaves of the marsh plants,and then burrow down to the root system which

Figure 3-14. Linear lakes between beach ridges near the mouth of
Bayou Lafourche. The photographs show an alternation of sandy
ridges (A) and swales (B) that are occupied by linear lakes. The
beach ridge complex formed during the last stage of the Lafourche-
Mississippi delta development. That is, after diversion of the
Mississippi River from the Lafourche (C) to its present course had
taken place. The swales were transformed into lakes as a result of
subsidence. Though continuing, subsidence did not yield an appre-
ciable expansion of the lakes during the 17 year period separating
the two photographs. Increased water area is mainly a result of
borrow excavation. On the other hand shoreline retreat along the
Gulf of Mexico (D) is noticable.

Arr

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WR
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1952

F--'P '1% 1 ;777%
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.8 410

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binds the organic soils together (O'Neil, 1949). Thus, the peaty floor

is broken to a depth of as much as 20 inches, and a mucky, rotten con-

dition is created. Once the binding root mat is destroyed, flooding dur-

ing the next high water period may create a lake.

Storm tides are known to be very effective in creating new marsh

openings. When water with salinities above 50 percent sea water is

carried into the fresh and brackish marshes and fails to runoff' rapidly,

a rotting-out of the vegetation occurs resulting in large scalds or areas

denuded of vegetation (Treadwell, 1955). If this takes place in fresh
floating marshes, the vegetation can be so completely destroyed that

permanent open ponds and lakes will form.

According to comparison of air photos taken at different periods,

the above three processes appear to be mainly responsible for widespread

openings in some areas, but the areal extent and relative frequency of

each occurrence are not known at this time. Figure 3-15 illustrates

the development of new marsh openings over a 20-year period.

Lakeshore Erosion

Subsidence drowns the marshes, but shore erosion along lakes and

bays also contributes appreciably to marsh loss. Where subsidence rates

are high, the outlines of lakes are very irregular, but where the expan-

sion of lakes is the product of lakeshore erosion by waves., the overall

outline becomes very smooth. Numerous oval or rounded lakes in the

coastal marshland of Louisiana belong to the latter category. Their

sizes vary greatly, ranging from tens of feet to more than 10 miles in

diameter. Good examples are provided by Wilkinson Bay Chien in the Bara-

taria Basin (Fig. 3-16). Treadwell (1955) attributes the initiation of

most of these lakes to marsh fires, animal eat-outs, and storms. He

Figure 3-15. Lake shore retreat and opening up of floating marsh,
Barataria Basin. Marsh deterioration appears to be serious in this
area of Bay L'Ours. Shore retreat is considerable and readily app-
arent at locations indicated by A. The marshes are of the floating
type with deterioration resulting in numerous small ponds (B) which
eventually will merge into larger lakes. The 1952 photographs shows
signs of extensive marsh burning, a practice related to trapping.
C and D indicate pipeline canals.

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to
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AN
A

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74
gn x A.

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fp

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1952, 42

Figure 3-16. Shoreline retreat along round lakes, Barataria Basin.
The photographs show a series of circular shaped lakes along the
northern margin of Barataria Bay. Close comparison of the two
photographs reveals a small but overall retreat of the lake shore
lines. Erosion is most apparent at the locations marked by A.
B marks a navigation canal which has widened considerably over the
18 year period separating the photographs.

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1952 19694-

states that in their initial stage this type of lake is of variable shape,

but over most of the fairly firm marsh initial ponds tend to be rounded

or oval. In areas of low, soft marsh, small ponds have irregular outlines.

Regardless of the initial lake form, continued erosion of lake shores

tends to round their outlines.

In addition to hurricanes, Treadwell (1955) places emphasis on

wind direction distribution throughout the year. No dominant

prevailing wind direction exists in coastal Louisiana. Southeasterly

winds prevail in spring, northeasterly in winter, and southwesterly in

summer. It is suggested that the wave erosion occurring during average

years tends to develop lakes with rounded outlines.

The size of small lakes increases slowly at first, but then grows

rapidly as wind fetch increases. If a lake continues to enlarge, it

eventually merges with other lakes. The merger of lakes of various sizes

results in large lakes whose shores are scalloped or arcuate. Through

the above facts, it can be generally stated that the rounded form of lake

is indicative of the firm and stable condition of the marsh such a lake

is seated on, while the irregular form is suggestive of the unstable

condition.

Hurricanes can be identified as a direct cause for lakeshore erosion

(Russell, 1936) and marsh breakup. Observations in southwestern Louisi-

ana following Hurricane Audrey indicate increases in marsh openings or

open water areas within the marsh by as much as 100 to 150 percent

(Harris and Chabreck, 1958). This type of destruction appears largely to

be the result of high velocity currents generated during seaward return of

floodwaters following inundation by the storm surge (Wright -et- -al.,
1970).

Most vulnerable to the high velocity water movement is the cane

vegetation, such as Spartina alterniflora and Spartina. patens. Related
to their growing cycle, density of the canes is largest during the

late summer when dead culms are still present in addition to the new

growth of the preceding spring. As a result, the cane forms a major
obstruction to flow. In exposed conditions, the root mat may be torn

from the soft substrate and large clumps of vegetation removed.

In addition to the mechanical action, hurricane surge may contribute
to marsh deterioration through prolonged inundation. Apparently, many

species of cane cannot tolerate total submergence for long intervals and

will die under such conditions (Chamberlain, 1959). Inundation f re-

quently is prolonged as water is retained by spoil banks that accompany

canals in the marsh area.

The seriousness of hurricane effects is further compounded by the
frequency with which hurricanes and tropical storms occur and the extent
of associated flooding. An occurrence interval of approximately two
years can be shown for the passage of hurricanes or tropical storms
through the Barataria-Terrebonne region (Hope and Neuman, 1971).

Plate 11 shows the area inundated during the passage of Hurricane Betsy

in 1965. Water levels were raised as far as 25 miles inland from the

coast, attaining a value of as much as 2.8 feet even in the des Alle-

mands area. Figure 3-17 illustrates the flooding associated with pas-
sage of Hurricane Hilda in October, 1964. Central pressure at the time
of landfall was approximately 28 inches (U. S. Army Corps of Engineers,

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SCALE IN MILES 125 mph 100 mph 75mph - _5 gPANY REPORT ON HURRICANE
0 10 0 .0 9 Ls 8 HILDA DATED: MAY 1966
A. FILE NO M-1-237-6

Figure 3-17. Flooding associated with the passage of Hurricane Hilda, October, 1964.

1966). Although the hurricane eye passed slightly to the east of the

Terrebonne area, related to the counterclockwise circulation, the impact

of the accompanying storm surge was felt to the largest extent in the

Terrebonne area. Water levels along the central Terrebonne coast were

raised nearly 8 feet above normal, producing extensive flooding.

Accompanying the passage of the hurricane was a heavy rainfall. Total

precipitation in the Terrebonne area ranged from 2.4 to 7.0 inches for

the period of October 3-5. Combined with the raised tidal levels along

the coast, this resulted in additional flooding of inland areas from

headwater overflow. As shown by Figure 3-17, nearly the entire Bara-

taria-Terrebonne area was inundated. The only exceptions were the high-

er natural levees along the upper part of Bayou Lafourche and its dis-

tributaries near Houma, and areas along the Mississippi River north of

New Orleans. Embanked areas along the lower Mississippi River also

escaped inundation. Flooding by tidal waters was clearly the most

extensive, reaching inland from the coast as far as Raceland and New

Orleans (Figure 3-17).

Fresh-Salt Water Mixing

Directly related to morphologic changes is the development of a

broad fresh-salt water mixing zone (Figure 3-18). In the absence of

human interference, fresh water is introduced periodically into the es-

tuaries as a result of overbank flow of the fringing Mississippi trunk

channel and its distributaries. This influx is augmented by precipita-

tion surpluses. As a result of the large storage capacity of the upper

estuary, related to the marsh-swamp environment and the numerous lakes,

BARATARIA BASIN SALINITY REGIME

Brackish Zone, 1961

............. .........
Brackish Zone, 1963
.. ... ... ... .. .....
..................... .......
.. ..........
.. ..... .............. ... ...........
...... .... ..... ... Fresh Water Influence
.. ........ ..
............. ...
7@ ....... ......... ............
..........-
.................
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................. ....... -1 ..... .....
.............
....... ....
................ ...............
....... ....... ... XX
.......... ........ ... ...
TO -""'"'::::::::::.:..... 1.1-1-1- .1.@.@.....@'.....,.,.@...@..,..@: _ 1:
....... ... .......... ..
Tidal Exchange
..........-

................
Ch
e XX
.............
........... Natural Levee
A
Mean Monthly Salinity RainTU I I X.
CO ...
Range, 1961 and 1963 :,:::Runoff. 0 10 20
30- Miles
.A
CL 00
00
00
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.............
..................
.............
.............
...................
...............
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...................
8 C
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............

...............
a 10- ........
V)
..............
bN
. ...........

. .........
Mississippi Effluent
A B C D Baratr BaY
Salinity Stations
Figure 3-18. Fresh-salt water mixing zone in the Barataria-des Allemands estuary system. Primary fresh
water input consists of locally derived runoff from catchment area bounded by crests of natural levee
ridges along the Mississippi River and Bayou Lafourche. Tidal exchange is controlled by size of passes
between barrier islands. The position of the brackish zone is contrasted between an exceptionally wet
(1961) and an exceptionally dry (1963) year.

and the characteristically sinuous nature of the drainage network,
fresh water is released seaward in a gradual manner. This gradual
dispersal tends to distribute fresh water surpluses over extended
periods, thereby reducing periods of fresh water shortage which lead to

increasing salinities.

Salt water influx in the lower estuaries is a function of a large
number of variables, in particular, tidal range, seasonal wind patterns,
shape and size of the estuarine tidal prism, and size and number of

the tidal passes between barrier islands. An additional variable is the
salinity of the incoming water which changes as a function of Mississippi
River discharge and offshore circulation. Limited depth of the bays
appears to be prohibitive to the development of a salt wedge and well-
defined vertical stratification of the water column. Mixing, as a result,
occurs predominantly in a lateral direction. Together with the gradual
dispersion of fresh water, this enhances development of a wide mixing
zone characterized by low salinity gradients. Consequently, optimum
biological habitats, in terms of salinity ranges, extend over wide areas.
This is probably most apparent in the wide belts of salt, brackish, and
fresh water marshes that occur in inland direction, but the same can be
said for a large number of marine organisms. This aspect translates into
a high biological productivity.

The Delta Cycle

The natural deterioration of the Lafourche deltaic COMPlE!x and
lower Barataria Basin has resulted in almost ideal estuarine conditions
(Figure 3-19). The broad salt water-fresh water mixing zone, highly

DES ALLEMANDS BARATARIA BASIN
S S S I P P 1 4
S
C'N
'VA(,-,

CREVASSE
DISTRIBUTARIES L A K 41
(ABANDONED) f.- D S
@ALLE S

"ZONE OF FRESH LAKES,
-,MARSHES AND SWAMPS
0&
...........
.............. .........
LACUSTRINE DELTA
........... .
4 4- 0 (ABANDONED),
I
0

..... ........
cl

6e
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.......:::LAKES AND MARSHES
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... I............. .
............... ......
................. ........
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...........
NATURAL LEVEE RIDGES A A y
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........ ....
BAYS AND MARSHES
BARRIER ISLANDS AND BEACHES (SAND) . .....

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

0 5 10 15 MILES
DELTA MARG!N ISLANDS
AND BEACHES
DISTRIBUTARY
MOUTH BEACHES
(ABANDONED)

Figure 3-19. Distribution of major environments in the des Allemands-Barataria estuary system.

BIOLOGICAL PRODUCTIVITY AS A FUNCTION OF THE DELTA CYCLE

PRESENT CONDITION OF THE MAJOR DELTA COMPLEXES
MARINGOUIN ST. BERNARD GLAFOURCHE
TECHE PLAQUEMINES
HIGH MODERN

MARINE
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RAPID SUBAERIAL GROWTH DETERIORATION
SUBAQUEOUS GROWTH
rTIME SPA>N
Figure 3,20. Relationship between biological productivity and the delta cycle. Ideal conditions for
estuarine organisms occur during early stages of deltaic deterioration.

irregular shoreline with extensiveland-water interface, broad, shallow

lakes and bays, extensive fringing swamps and marshes, and protective

barrier islands associated with the early stages of delta lobe deterior-

ation result in an estuarine situation that is ideally suited for many

important species of marine organisms.

Figure 3-20 illustrates the relationships between the principal

variables controlling biological productivity in the Louisiana coastal

zone and the deltaic cycle. It can be demonstrated that biological pro-

ductivity along any major segment of the Louisiana coast between Chenier

au Tigre and the Chandeleur Islands is to a large extent a function of

the delta cycle. The better combinations of the principal variables and

proportion and areas of various habitats occur during early stages of
deterioration. Such conditions presently exist in the study area.

It should be recognized that a number of processes that have con-

tributed to creating an optimum estuarine environment continue to oper-

ate. This means that subsidence and erosion will propagate further
disintegration of the marsh surface, as is well illustrated by the Breton-

Chandeleur estuary. This estuary relates to the older St. Ber).'Iard
delta complex to the east of the present Mississippi River course. Here,

an estuarine environment similar to that of the Barataria-Terrebonne

region can be identified. However, deterioration has progressed to a
much higher level, only limited protection is rendered any more by a
severely eroded barrier chain, and the width of the mixing zone is
relatively small. Correspondingly, biological productivity has shown a
gradual decline, which indicates that progressive deterioration eventually

induces a decline in productivity.

Continuing deterioration in the Barataria-Terrebonne wetlands has

been documented in previous studies, most notably by changes in areal

land-water ratios. Wetlands in the saline to brackish estuarine zone

presently are lost at annual rates ranging from one to three acres per

square mile. In part, this can be directly or indirectly attributed to

human enterprises. Partly, it relates to ongoing subsidence, resulting

in an increase of water area and salinity encroachment. Without doubt,

it can be stated that man's activities accelerated and continue to accel-

erate the process of deterioration.

The effects of this are already noticeable. Examples are found in

inland movement of the coastwise vegetational zonation pattern as display-

ed by the marshes, and an inland extension of the distribution of the

oyster leases. Chabreck (1970) indicates a landward movement of two miles

since the 1940's for the salt water-brackish water marsh boundary. This

shift relates to salinity encroachment, which, at the same time, increases

salinity gradients up the estuaries.

If indeed environmental conditions of the Barataria-Terrebonne area

were nearly optimum prior to the man-induced disturbances of an establish-

ed equilibrium, it follows that measures should be taken to retard fur-

ther deterioration of the wetlands. This would require, when feasible,

retardation, modification, or elimination of those processes and human

activities that enhance a decrease of areal land-water ratio, and remove

marsh surface from the estuarine system, induce salinization, and increase

salinity variance. Manageable processes and activities should be therefore

identified with regard to environmental effect.

MANAGEMENT OF NATURAL PROCESSES AND HUMAN ACTIVITY

Two major natural processes can be identified that are critical

to the estuarine environment and to which management methods can be

applied to sustain optimum conditions. These are: 1) the influx and

distribution of fresh water, nutrients, and sediments, and 2) encroach-.

ment of saline waters. Past and present human activities affecting

these processes include the confinement of the Mississippi River,

mineral extraction, expansion of urban and industrial complexes, and

reclamation.

Until construction of Mississippi River levees for flood protection,

and the severance of Bayou Lafourche as a distributary, the Mississippi

River provided the major influx of fresh water, sediment, and nutrients

into the Barataria and Terrebonne estuaries as a result of crevassing

of natural levees and overbank flow. Elimination of this river water

greatly contributed to the present state of the estuarine environment.

Previous reports of the Hydrologic and Geologic Studies of Coastal

Louisiana dealing with sediment requirements have attempted to establish

volumes of supplementary freshwater and sediment required to partially

offset land loss and to prevent further salinization (U. S. Army Corps

of Engineers, 1970; Gagliano, Light, and Becker, 1971).

Of equal significance with regard to the hydrologic and salinity

regimes has been the dredging of numerous canals, notably for the

purpose of mineral extraction and transport, and for navigation. In

the Barataria-Terrebonne region specific values can be placed on the

area of wetland transformed into canals for different purposes (Plate

16). Measurements reveal a total of 106 mile 2 of canal area, which

constitutes 2 percent of the total region. This does not include

the wetland area modified as a result of deposition of dredge spoil

on the canal banks. Of the total area of canals nearly 70 percent

is related to the mineral extraction industry and includes access

canals, rig cuts, and pipeline canals. Most of these are located in

the brackish-to-saline marsh belt, notably in the Barataria Basin.

Major oil fields show a canal density, which is the ratio unit of

canal area per unit surface area, ranging between 0.15 and 0.25.

Drainage canals represent the second major category, followed

by navigation canals. Drainage canals occur in restricted areas

(mostly the freshwater environments), and are predominantly assoc-

iated with either urban or agricultural development of natural levees,

or reclamation projects for the same purposes. As a result, canals

are generally in direct conflict with the natural drainage system.

Their linear configuration and depth tend to accelerate removal of

freshwater from the swamps and marshes, thus reducing the retention

capacity of the basins. Also, dredging spoil tends to confine water

movement, thereby diminishing lateral dispersion of freshwater through

the estuarine system. The canals in turn, affect the distribution

of freshwater temporally as well as spatially.

A third cause for disruption of the natural drainage system

is a conflict between canal alignment and topography. In many cases

canals dissect a natural watershed transverse to its gradient, which

under the prevailing low gradient conditions is likely to direct

flow from the upper watershed along the canal, thereby reducing

dispersion into the lower watershed, creating freshwater deficient

areas.

A similar stress arises from the construction of highways

across major basins such as highway U.S. 90 between New Orleans and

Houma. In those cases where the road is not confined to a natural

levee or raised, the road embankments traversing the swamp or

marsh severely limit the dispersion of freshwater. Freshwater runoff

is redirected to a limited number of passages into the lower part of

the basin provided by canals or culverts.

The dredging of canals has an additional effect upon estuarine

conditions since it represents a physical removal of marsh surface

from the estuarine system. Not only does this decrease the area of

biological habitats, but it deprives the estuary of part of the influx

of organic matter. In particular, the influx of organic detritus

derived from the salt water marshes has been suggested as an important

factor with regard to biologic productivity (Day et al.,1973).

In regard to the salinity regime, the dredging of canals,

especially of those that are navigable and open to saline bays, is

believed to have substantially contributed to a recorded increase of

salinities over the past 25 years. This holds true particularly for

the dredging of channels that provide ship access from the Gulf of

Mexico to coastal communities and that traverse the shallow bays and

salt and brackish marshes. The Barataria Waterway and the Houma

Navigation Canal are notable examples where saltwater intrusion has

been commensurate with the increase in water depths. Cypress dieback, e.g.,
in the vicinity of the Houma Navigation Canal near Dulac, Louisiana,

is only one of the measureable ecological effects of such change.

The effects of drainage and reclamation of wetlands on the

estuarine environment extend beyond the removal of blocks of swamp

and marsh habitat from the natural system (reclaimed areas are identi-

fied on Plate 8). Drainage and reclamation may also contribute to

formation of large water bodies. It has been documented that, in several

cases, reclamation projects have failed. Examples are shown in Figures

4-1 and 4-2. Following dike construction and removal of water, the

exposed, highly organic clays become subject to shrinking as a result of

water loss and oxidation of organic matter. The resulting decrease in

surface elevation required excessive drainage efforts that in most cases

were not warranted in view of the cost-benefit ratio for the reclaimed

area. Abandonment of the project subsequently resulted in flooding,

creating an open water body large enough to allow wave erosion at its

shores, and deep enough to prevent re-establishment of marsh or swamp

vegetation.

Abandonment of drained swamp and marsh areas is mostly restricted

to agricultural projects. However, in those cases where reclamation

occurred for the purpose of urban expansion, notably in the New Orleans

area, the result frequently is equally undesirable. The effects of

soil instability require excessive structural maintenance, while

subsidence requires a public expenditure for drainage and flood protec-

tion that appears unwarranted when considering available alternatives

Figure 4-1. Submerged fields, Barataria-basLn. Photographs show
failed reclamation project at the intersection of Bayou des Alle-
mands and La. Hwy. 90. A series of ponds such as indicated by A
resulted as the reclamation project was abandoned. Drainage canals
are still visible (C). Considerable enlargement of the ponds
occurred over the period of 1952 to 1969. Formerly isolated from
the principal drainage channel of the Barataria basin (Petit Lac
des Allemands), the ponds now are connected to this water body.
The shores of Petit Lac des Allemands also show signs of erosion
(D). B indicates relics of overbank crevasse splays that originated
along the Mississippi River.

op,

.16

@1952
r

M. "I'vowi

cona a /T

t7a/ Na

wm.,

A NN

1969

Figure 4-2. Submerged fields, Barataria basin. Attempts to expand
cultivation from the natural levee of the Mississippi River (A) into
the wetlands failed and resulted in the ponds shown on the photographs.
Cultivated fields on the natural levee are indicated by B. Since
1952 fresh water marsh in the area has deteriorated considerably as
shown by comparison of the photographs at location C. D indicates
a swamp area, which forms the transition from the well drained levee
to the fresh water marsh.

'40

ag @k
Q
At
OV/

2,
at

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!iM

lp,

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Waggamon.

11 xi-
IN

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1969ii,

for urban development.

Shoreline retreat and deterioration of the barrier islands

fringing the estuaries is among the most critical environmental

problems in the area . This is because of the importance of the island

chain in reducing storm generated surges, regulating water exchange

between the Gulf and estuaries, as valuable natural habitats, as

scenic areas, and as areas with a high recreation potential. Deter-

ioration of the islands relates to both natural and man-induced

processes. Critical factors are a limited sand budget, a continuous

reworking of the barrier sediments in response to incident waves,

wave-induced and coastal longshore currents, interruption of long-

shore sediment transport by navigation channels, and navigation and

shore protection structures.

The general dynamic and geologic aspects of the two barrier

systems, Isles Dernieres and Timbalier-Grand Isle, are illustrated

on Plate 12. Related to shoreline orientation, dominance of south-

easterly waves, and coastal currents that diverge in the vicinity of

Belle Pass, net longshore sediment transport is directed to the west

along the Timbalier Islands and the Isles Dernieres, to the east along

most of the Caminada Beach Ridge complex , and along Grand Isle and

the Grand Terre islands. Morphologic evidence suggests a convergence

of beach drift in the area east of the Grand Terre islands.

In response to the general longshore drift,the islands migrate

alongshore as a result of erosion at their updrift ends, and depo-

sition at the downdrift ends in the form of recurved spits. In

addition, the islands are subject to inland migration in response to

a subsiding substrate. As a result of increasing water depth, sediment

removed from the seaward side of the islands is in part deposited at

their downdrift ends but slightly further inland. Also, sand is moved

to the back of the islands by hurricane storm surges and deposited as

wash-over fans.

With respect to sediment movement, the barrier chains east and

west of the Caminada beach ridge complex can each be viewed as a

separate open system through which sand is moved,with the barrier

islands providing temporary storage. Sediment input is derived almost

totally from shore erosion along the Caminada beach ridge complex.

Here recession of the shore line is in the order of 50 feet annually.

Sand added as a result of reworking of the subsided and submerged

deltaic plain surface over which the islands migrate is probably

negligible in comparison. During longshore transport of sediment

derived from the beach ridge complex or released from storage in the

islands, sand is lost temporarily or permanently. Temporary losses

result from the movement of sediment into the bays by flood tidal

currents and subsequent deposition as tidal deltas inland from the

passes. This sediment may in part be reincorporated following inland

migration of the islands. Permanent loss of sand results from off-

shore movement of sediment by tidal currents and wave motion, and

from deposition at depths that are below the lower boundary of

sediment reworking during migration of the barrier system.

A critical factor with regard to longshore sediment movement

is the presence of an arcuate bar seaward from each of the major

tidal passes connecting adjacent barrier islands. The bars are, in

essence, formed by deposition of sand from ebb tidal currents. Limited

water depths over these bars allow continuous entrainment of sediment
in this area so that in combination with longshore process components,
the bar provides for natural bypassing of the tidal inlets. This

insures sediment input on island downdrift from each inlet.

The above described general dynamic framework of the barrier

system allows indication of a number of human enterprises that can be

considered detrimental to the prolonged existence of the barrier

islands. These are the placement of structures perpendicular to the
shore line, the dredging of tidal passes, and the dredging of numerous
canals along the backshore of the islands--notably Timbalier Island.
The dredging of tidal passes affects both the sediment budget and
sediment movement. Since the offshore bar associated with the passes
is the main obstruction to navigation, dredging tends to include the
removal of part of the bar. This reduces the possibility for sediment
to bypass the inlet, thus partially depriving downdrift islands of

necessary sediment input. Furthermore, sediment entering the dredged
channel will. in part be moved offshore and in part be withdrawn from

the system as it is incorporated in reestablishment of the bar. Off-
shore sediment movement, as well as movement into the bays, may be
increased when dredging induces velocity increase of the tidal currents

through the inlet.

Placement of groins and jetties may also cause serious inter-
ception of sediment in longshore transport, depending on storage

capacity of the updrift area. Storage in the updrift area consequently

reduces the input of sediment downdrift which will, under the present

circumstances, result in serious erosion. Even though sediment input

may be halted only temporarily, the erosion may do irreparable damage

to those barrier islands which hold only a very limited amount of sand

in storage. For instance, thickness of the sand deposits making up

the Isles Dernieres is only on the order of 5 feet (Plate 12). Since

most of the islands also have a critically small width, even slight

additional short-term erosion may result in a breaching of the island

and complete deterioration. In this respect it should be pointed out

that the chain of barrier islands is no stronger than its weakest link.

That is, the complete deterioration of a single island may result in a

wide tidal inlet and a long-term reduction of sediment input into down-

drift islands. The deterioration process thus could be perpetuated.

Notable effects of engineering works are found on the Grand Terre

Islands, East Timbalier and Timbalier Island. Erosion of the Grand

Terre Islands has been accelerated as a result of the long jetty built

at the eastern end of Grand Isle for the purpose of creating a sand

storage reservoir. Dredging of a new Belle Pass inlet channel adjacent

to-and replacing the original channel greatly accelerated erosion along

East Timbalier. Comparison of the 1953 Belle Pass topographic map, and

1968 and 1972 aerial photography, shows that shoreline retreat over the

period of 1968 to 1972 following completion of the Belle Pass channel

approximately equaled retreat over the period of 1953-1968. This means

a fourfold increase in the rate of shoreline retreat. The effect of a

jetty placed near the western end of East Timbalier Island has resulted

in a significant landward offset of the downdrift shoreline and breach-

ing of the spit extending westward from the jetty.

A major factor contributing to deterioration of the islands is

the dredging of canals for mineral extraction purposes on the bay side

of the islands. Such canals are evident on Timbalier Island, East

Timbalier Island, the easternmost side of the Isles Dernieres, and the

Grand Terre Islands. These canals make the islands highly vulnerable

to breaching, a condition that is further enhanced by the migration of

the islands which places the canals ever nearer the seaward margin. Not

only may breaching occur as a result of wave runup on the seaward side,

but part of a returning storm surge in the bays will be directed into

the canals, resulting in amplification of the surge height. The canals

further form a sediment trap resulting in withdrawal of sand from the

barrier system. Here again, even though storage of sand in the canals

may be temporary, the islands may not be able to absorb additional

decreases in sediment input.

MANAGEMENT PLAN

Through the outlined approach involving simultaneous consideration
of geologic and hydrologic processes, human activities, and key environ-
mental parameters, it has been possible to arrive at a plan for management
and development of the Barataria-Terrebonne area, including both its
land and surface water resources. Plate 21 of the atlas presents the
multi-use development and management plan. As the plan attempts to

sustain or produce an optimum environmental balance through recognition
of environmental units with specific constraints and opportunities, it
indirectly identifies present and proposed activities and projects that

are incompatible with optimum use of the area. These conflicts are

identified on Plate 22. An additional need that has been recognized
is the use of innovative engineering approaches in the design of projects

necessary for implementation of, for example, water diversion or shore

protection. Such projects should become assets to the overall environment

rather than being directed to only the technical solution of a design
problem. Thus the problem also becomes one of environmental engineering.

Management and Development Areas

The management and development plan is based upon two major.concepts.

The first is that of a corridor-basin relationship. Within the coastal

zone are two broad, natural land systems: the natural and protected
levee ridges where historically human settlement has taken place, and
the wetlands that throughout history have been the major renewable resource
base of the state. The plan recognizes the value of this physiographic
and historic pattern by emphasizing the levee systems as transportation

and development corridors, and stressing conservation of the wetlands as

water system recharge and natural resource development areas.

The second concept recognizes the need for successive and changing

land use in an orderly and sequential manner. This is necessitated by

the dynamic nature of the natural systems of the coastal zone. We must

recognize and accommodate natural changes by modifying land use through

time. The system cannot be held in a static condition.

The concept of sequential use can be extended to man's activities.

Facilities for mineral extraction, industrial plants, and certain public

works projects have a limited life expectancy. When such facilities

are designed, an attempt to predict some future land use of the site

should be made to avoid irreversible environmental modifications that

are not compatible with predicted future use.

The map (Plate 21) presenting the management and development plan

shows the five types of environmental units that are recognized. Each

unit is characterized by a specific set of natural and cultural elements

that determine its optimum use. The units represent natural entities

with their boundaries determined by natural contacts, ranking of environ-

mental constraints and opportunities, and by historic and projected land

use patterns. The defined environmental units are: Barrier Island and

Gulf Shore Areas, Estuarine Nursery Areas, Fresh-Brackish Marsh Areas,

Freshwater Basins, and Development Corridors.

Barrier Island, Reef, and Gulf Shore Areas

These areas represent the first line of defense against hurricane

forces and marine processes, and are the key to regulating water exchange

between the estuaries and the Gulf of Mexico. Tidal passes associated

with the barrier islands can be viewed in part as control valves of the

estuaries. The islands furthermore are invaluable as wildlife habitats

and scenic recreation areas. Large shell reefs in the Point au Fer area

represent a coastal barrier as well.

In particular, the barrier islands are undergoing rapid changes as
a result of coastal erosion (Plate 12). Accelerated regional subsidence,
hurricane damage, and man-induced changes such as dredging of canals on
the bay side of a number of islands are the main contributing factors.
Frequent hurricanes and coastal erosion are a continuous threat to life

and property where permanent development occurs. This is well illustrated

by Grand Isle, even though this is the most stable of the barrier islands.
The island is accessible by highway and has become important as a recrea-
tion area, as a base for the offshore oil industry, and as a fishing port.
This development and the related shore protection are incompatible with
the necessary sustenance of certain coastal processes and optimum use
of the islands. Similar permanent development of other barrier islands

should be discouraged.

It is recommended that top priority be placed on management of
these units as natural barriers against marine forces (including tidal
inflow and outflow of Gulf water) and as wildlife and scenic-recreation

areas. Their maintenance is vital to the continuing viability of other
natural systems in the coastal zone. The only feasible approach to
maintenance of the barrier islands is to insure continuity of the wave-
and current-driven system of sand nourishment and redistribution. The

nourishment sources for the barriers in the study area are old beach
ridges and channel deposits. The sand is released through erosion of

these deposits. For this reason erosion along some segments of the
coast must be allowed to continue. A specific example is found in the

vicinity of Pass Fourchon.

Longshore sand transport should not be disrupted by channel deep-
ening or the construction of jetties. Sand transport across natural
tidal passes is accommodated by arcuate bars that span the full width
of the pass on the seaward side. When these bars are dredged for navi-
gation.improvement the transport system is disrupted by allowing increased
escape of the sand from the longshore drift system. This in turn results
in accelerated erosion on the downdrift side of the pass unless provisions
are made for sand by-passing. Sand by-passing plants have been used in

other areas to alleviate such problems.

The barrier islands must be maintained in order for the existing
estuarine system to flourish. Detailed studies of erosion and deteri-
oration of the barrier islands should be initiated immediately in
order to implement restoration and management. These studies should
address a number of problems related to sand nourishment and transport.
Specifically, studies should be made of 1) sources and quantities of
sand available for supplementary nourishment; 2) the advisability of
attempts to maintain the shoreline of Grand Isle in its present position
when viewed in relation to the overall barrier system and the effect of
subsidence; 3) possibility and desirability of preventing breaches in
barrier islands such as East Timbalier Island; 4) feasibility of closing
enlarging tidal passes such as those of Grand Terre Islands; 5) the
sand budgets for individual islands, barrier complexes, and the barrier

system as a whole in order to allow for long-term planning and management;

6) the possibility of bringing the islands into public ownership. They

are so vital to the future of the coastal zone that they should be in the

public domain since present regulations related to private ownership

prevent effective management and restoration.

Estuarine Nursery Areas

From the standpoint of biological productivity, the estuaries

represent the most productive acreage in the state. Not only are they

the foundation of the state's fishing industry, but they provide impor-

tant habitats for migratory waterfowl, fur-bearing animals, and reptiles,

and are important scenic-recreation-open space areas. The units are

defined on the basis of distributions of salinity, marsh vegetation,

oyster beds and length of land-water interface per unit area.

These areas should never be drained or reclaimed for other uses,

even agriculture. Recent overflights indicate that thousands of acres

of marsh in the estuarine nursery areas are in an advanced state of

deterioration. Programs of marsh restoration and management should have

the highest priority and should be initiated immediately. Such programs

should include a detailed systematic evaluation of the marsh condition

followed by a water management program designed to conserve runoff,

reduce salt water intrusion, and curtail erosion.

Although the map is intended to be a clear statement that the

primary management objective in these units is for renewable resources,

we also realize that mineral extraction industries are active in these

areas. If it becomes necessary to drill new wells, develop new fields,

or lay new pipelines, the surface modification associated with these

activities must be made compatible with the primary management objective.

The concept of sequential use is also important. Since an oil

field has a life expectancy of 35-70 years, we must plan for future use

of areas now occupied by fields. In many instances, creative planning

of canal geometry and spoil disposal could create new habitats, conserve

freshwater runoff, and enhance the environmental setting. In general,

canal dredging should be minimized. Directional drilling should be

used to reduce the number of well locations and pipelines should be con-

fined to corridors. Surface features should be considered in all future

mineral industry planning. These same guidelines apply to extractive

industry activities in all of the renewable resource management areas, and

will not be repeated.

Fresh-Brackish Marsh Areas

Largely unbroken fresh to brackish marshes and associated lakes,

ponds and waterways occupy a major portion of the estuarine zone adjacent

to the Gulf Intracoastal Waterway (GIWW). They are delineated on the

basis of distributions of salinity, fauna and flora, configuration of

streams and water bodies, and length of water interface per unit area.

Like the estuarine nursery areas, these marshes are vital components of

the highly productive estuarine zone. They are of primary importance.

to migratory waterfowl, fur-bearing animals, and commercial species of

reptiles (alligator). They provide scenic-recreation-open space areas, and

are of considerable value to the commercial fishing industry. In addition,

these marshes, along with other renewable resource areas located south

of the GIWW, provide a critical buffer zone against storm generated

surge and prevent serious inundation of inland communities. With re-

gard to land use, it should be pointed out that in these units, thick

underlying deposits of peats and soft clays provide poor foundation

conditions.

Priorities and management recommendations are essentially the same

as those outlined for the estuarine nursery areas.

Fresh Water Basins

Three major fresh water basins are identified on the map. All lie

north of the GIWW. They are dominated by extensive swamps and marshes,

rounded lakes, and sluggish backswamp drainage networks. They are

usually underlain by thick deposits of peat and organic clay, which

provide very poor foundation conditions and limit land use. Their value

as wildlife habitat areas is well known not only to the sportsmen and

naturalists of the region, but to a large segment of the general public

as well. These basins are also important as natural reservoirs ensuring

fresh water flow into the estuarine zone south of the GIWW throughout the

year. This fresh water influx is one of the primary factors in controlling

water chemistry in the estuarine zone south of the GIWW. Alteration of

the flow regime in some of these basins through drainage projects, canal

dredging, flood control projects, and highway embankments is presently

one of the major factors in increased salt water intrusion in the

estuaries.

These basin must be managed as renewable resource areas. Forestry,

fisheries, and recreation are the main uses recommended. Dredging should

be minimized, and draining and reclamation prohibited. In most instances,

highways traversing the basin should be elevated on piers or piles.

In general, introduction of any new linear elements should be dis-

couraged. If unavoidable, they should be confined to corridors parallel

to existing highways, pipelines, etc. Water storage in the basins should

be managed in order to optimize water chemistry in the estuaries to the

south.

Existing corridors traversing these basins should be de-emphasized

from the standpoint of development. For example, U.S. Highway 90 be-

tween Boutte and Raceland is an important transportation link, but should

not be encouraged as a development corridor.

Guidelines pertaining to the mineral extraction industry are essen-

tially the same as those proposed for estuarine nursery areas. In

addition, construction of tramways or roadway embankments in inland

swamps and marshes should be minimized. Such features often redirect

fresh water runoff in the basins and provide obstacles to the movement

of aquatic and terrestial animals.

Development Corridors

In general, areas suitable for development are those places that

have good foundation conditions, good drainage, and are reasonably safe

from flooding. Natural levee ridges form the higher, positive topo-

graphic elements in the Barataria-Terrebonne region that are designated

as suitable for development. Historically, agriculture, industry, and

settlement have been largely restricted to these areas. Attempts to

extend these activities to adjacent wetlands have often proved to be

catastrophic.

The key to proper use of these areas is careful planning. A
good mixture of urbanization., industry, and agriculture in these areas
will insure both orderly growth and economic development and a good place
for people to work and live. Soil and meteorological conditions should be

mapped in detail and suitability for agriculture ranked. Prime agri-
culture areas should be identified and promoted in every way possible.

The development corridors are primary elements in the proposed
multiuse management plan. They represent areas that are already heavily
developed or where development is projected. In most cases, the cor-

ridors are confined to land surfaces that are suitable for development.
In some instances, however, "natural" corridors have been expanded to
boundaries formed by prominent man-made features, such as major naviga-

tion canals or flood protection levees. For this reason, some of the

land included within the development corridors has poor foundation condi-

tions and is flood prone. The rationale for expanding some natural

corridors is to provide adequate area for development so that random

extension into renewable resource areas can be controlled.

In addition to land suitability, locations of development cor-

ridors are dictated by major land and water arteries, historic land

use patterns, and the necessity to maintain rather than dissect exist-

ing natural entities. The term"development corridor"is not meant to imply
blanket urbanization or industrialization. Creative planning is again

recommended to provide the best mix of land use in these areas. The

primary use, however, is for development.

Public works projects should be focused on the corridors to strengthen

and further define them. Highwaysflood protection levees and structures,and

drainage projects, should be incorporated into the corridor plan.

Such projects should be combined wherever possible to minimize land

acquisition and costs. There is no reason, for example, why highways

cannot be constructed on the crests of levees. This is a standard pro-

cedure in the Netherlands and many other parts of the world. Water

resource management, mass transit systems, and regional waste collection

treatment systems should likewise be incorporated into the corridors,

as should linear elements such as pipelines and power lines.

The contact between corridors and intervening resource management

areas presents an interesting challenge to the planner. Should it be

smooth or crenulated? Should access points between development corridors

and marshes or swamps be linear or nodal? Only detailed environmental

analysis can provide the answer to these specific planning and design

decisions.

In some instances, the continuity of a development corridor depends

on a transportation link across a wetland area. A classic example occurs

between Lafitte and Larose. We believe that a transportation link between

these two places is important to orderly development of the coastal zone.

It is also recognized that excessive development across this area is

likely to cause a serious deterioration of the rich Salvador-Barataria

estuary system. In these instances, we propose, therefore, that future

highways be elevated on structures with permanent restrictions against

off ramps. This same principle can be applied in a number of critical

areas; notably, in the St. Charles Parish wetlands along the south shore

of Lake Pontchartrain where I-10 and 1-410 will join.

Geometry for Development

The development corridors shown on the plan represent an excellent

geometry for future growth and development of the study area that is

compatible with management of renewable resource areas. In a broader

context, the corridor should be viewed as part of a great oval linking

Lafayette, Baton Rouge, Hammond, Slidell, New Orleans, Larose, Houma,

Morgan City, Franklin, and New Iberia. This oval-shaped corridor is one

of the most basic elements in the orderly use of the overall coastal

zone (Fig. 5-1 ). Reinforcement of this corridor would have highest

priority. The southern Lafayette-Houma-Slidell arc is of particular

importance. An interstate highway along this arc would be very

important. Improved transportation along this arc would provide easy

ingress and egress to the coastal zone, making its opportunities avail-

able without necessitating overpopulation. Urbanization should be

encouraged on the well-drained surfaces near the poles of the oval.

The Slidell-Hammond-Baton Rouge area and the Opelousas-Lafayette-

New Iberia area satisfy most of the site requirements for good urban

development. Much of the southern arc of the oval is suitable for

urbanization, though on a somewhat reduced scale. The Thibodaux-Houma

area, for example, should eminently provide for urban growth. The channels

and natural levee ridges of the Mississippi River and Bayou Lafourche

represent major trans-coastal development corridors, and the State's

most important gateways to the Gulf. This corridor should be reinforced,

although its capacity must be determined. Is there a limit

to industrialization in this corridor, or can every acre of the natural

_F_ o_
E] NATURAL TRANS-COASTAL CORRIDORS
9" MAJOR NATURAL WATERWAYS X/,
UPLANDS
- MAJOR CANALS
0 PORT AREAS UPLANDS
MAJOR URBAN AREAS
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X.
Lafayette
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............
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TRANSPORTATION & W
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Figure 5-1. Major elements for growth and development of the Louisiana Coastal Zone.

levee be utilized? The banks of the Mississippi River are already lined

with industry, and many additional plants are anticipated. Air and water

pollution are an inevitable consequence of this industrialization. To

what extent can the natural system absorb even a minimum of pollutants?

Despite these unknowns, the Mississippi River is and will continue

to be the State's most valuable asset. The lower end of the Mississippi

corridor should be reinforced. Venice is destined to become an even more

important support facility for the offshore oil and gas industry and

future superport development.

The Lafourche corridor should be reinforced with improved highways

and flood protection. However, flood protection levees should not be

extended south of Golden Meadow. The proposed Lafourche by-pass channel

would define the western margin of an expanded natural corridor. The

beach ridge complex near the mouth of Bayou Lafourche at Port Fourchon

may serve as a foundation for onshore port facilities, related to a

deep water harbor. Although some port facilities may be permitted,

permanent development of petrochemical or other heavy industry should be

discouraged because of -incompatibility with recreation uses and maintenance

in the adjacent Gulf Shore areas.

Minor trans-coastal corridors within the study area include Bayou

Grand Caillou, Bayou Petite Caillou, Bayou du Large, and the Atchafalaya

River. Each of these corridors will play an important role as outlets

for recreation, the fishing industry, the offshore mineral industry,

and to some extent, as commercial ports. However, further widening

and deepening of associated navigation channels is discouraged because

of the salt-water intrusion problem.

The roles of other minor development corridors in the upper coastal

zone are apparent from their locations and form. The geometry of the

development corridors and environmental management units lends itself

well to evaluation of both the proposed deep water port to be located

off the Louisiana coast, as well as regional air carrier terminals.

Elsewhere (Gagliano, van Beek, Rowland, 1973) we have indicated that the

best probable site for the superport would be in the west delta area

near Southwest Pass. Only the Mississippi corridor can service, with

minimum impact, an initial oil port and later stages of the facility

which may include containerized and break-bulk cargo handling.

There is presently a rash of proposals for new towns and harbor

towns in the coastal zone. A number of these proposals involve the use

of public lands or require government assistance in the form of flood

protection, drainage, access roads, and other aspects of site preparation.

A number of the proposals would involve significant loss of wetlands and

create major water pollution problems. There are many excellent sites

for new towns within the development corridors and those areas suitable

for development. The consumer will pay heavy penalties in increased

site preparation, maintenance costs, and tax burdens for any urbanization

or development in the wetlands areas of the coastal zone. All land reclam-

ation, including "Florida-type" canal and homesite developments, for

urbanization should be prohibited.

The new community concept is an excellent one. New town property
placed within development corridors would guarantee a more orderly

growth of the region. A limited number of harbor towns at carefully

selected locations would also be a major asset. However, the locations

should be pre-determined by the geography and hydrology of the region,

and not simply by the wishes of the land developers. Since harbor

towns can have major environmental impact, additional study is recommended

to determine favorable locations and sizes.

Surface Water Resource Managment

I Management of surface water can be considered the most important

single part of the overall plan. This is because the wetland-bay

complex represents the major renewable resource of the study area, and

the viability of this complex depends primarily on its hydrologic and

salinity regimes. The surface water management plan as presented in

Plate 20 of the Atlas is aimed at establishing the most favorable

ecological condition through management of the regimes by means of

controlled retention and release of fresh surface water.

To establish optimum ecological conditions, it is necessary to

prevent further deterioration of the wetlands and to maintain or restore

the broad mixing zone that initially resulted from a natural balance

between locally derived runoff, water introduced by overbank flow of

the Mississippi River and its distributaries, and exchange with saline

waters of the Gulf of Mexico. This balance, as well as the overall

estuarine environment, has increasingly been subjected to stress as

a result of diminished fresh water influx related to levee construction,

reduced fresh water retention and diffusion as a result of canal dredging

and drainage projects, and increased salinities related to both of the

above. Consequently, the three main elements of the surface water manage-

ment plan are 1) the introduction of supplementary fresh water, 2) the

conservation or retention of runoff, and 3) the release and distribution

of fresh water.

The plan is based on earlier derived quantitative relationships

between salinity fluctuations within a given hydrologic unit and fresh

water runoff derived from precipitation within that same unit (Gagliano

et al., 1970). These relationships in turn made it possible to establish

the volumes of supplementary fresh water required to maintain desired

salinity conditions as defined by the positions of the 15 ppt isohaline,

and the brackish-salt marsh contact (U.S. Army Corps of Engineers, 1970;

Gagliano, Light, and Becker, 1971). Water needs for hydrologic unit IV,

the Barataria basin, and hydrologic unit V, the Terrebonne area, are

shown by frequency of need in Figures 5-2A and B,, respectively. Loca-

tions and maximum volumes of fresh water diversion into these units are

shown on Plate 20 .

A principal element in the management of the hydrologic and salinity

regimes is the reinforcement of three fresh water basins north of the Gulf

Intracoastal Waterway (GIWW) as retention areas. These basins are identi-

fied on Plates 20 and 21 as the Verret, Fields, and Salvador Basins. Three

major diversion structures are proposed for the introduction of fresh water

into these basins from the Mississippi and the Atchafalaya Rivers.

As each basin is contained between natural levee ridges, construction

of a continuous levee system along the GIWW would allow each basin to

function as a reservoir where fresh water can be held in order to meet

demands during period of precipitation deficit and increased salinities

in the lower estuaries. The levee is proposed along the southern side

of the GIWW to allow use of this waterway as a conduit interconnecting

the fresh water basins, and for redistribution of water along a continuous

arc fringing the estuarine area into which fresh water is to be introduced.

V20

0
............ ........... .................................................
...........
............ . . . . . . . . . . - - - - - - - - - - - - - - - - - -
15 -
C

...........
E

...........
10 ""MEMMM
...... ......

0
JAN FEB MAR APR MAY JUNE JULY AUG SEP OCT NOV DEC

50% exceedence
----20% exceedence
10% exceedence
............. 4% exceedence

Figure 5-2A. Preliminary water needs for salinity alteration and/or
water-level management, hydrologic unit IV.

20
0

15
C ............... . ...............................................
............ ........... ..........
E
.. . . . . . . . .... . . . . . . . ... . . . . .

0 JAN FEB MAR APR MAY JUNE JULY AUG SEP OCT NOV DEC

50% exceedence
---- 20% exceedence
10% exceedence
............. 4% exceodence

Figure 5-2B. Preliminary water needs for salinity alteration and/or
water-level management, hydrologic unit V.

Locks would be required where major waterways connect with the GIWW.

The conversion of the present basins to fresh water reservoirs is not

to mean the creation of three continuous lakes. Rather, the retention of

fresh water in these areas should be part of a managed backwater regime in

which water would not be raised by more than one or two feet above the

present levels.

To effectively manage the supplementary water, two options are en-

visioned with regard to its release from the fresh water basins. The first

is a release through the proposed locks on the major navigation channels

connecting the basins with the Gulf of Mexico. This would allow removal

of excess water from the basins without significantly affecting the managed

estuarine conditions.

The second manner of release would be directed toward management of

the estuarine conditions. It would require the diffusion of fresh water

through the estuarine system at all times when salinities need to be

reduced or the encroachment of saline water checked. For this purpose, a

large number of delivery structures is proposed through which water can

be slowly released from the freshwater basins and GIWW into the marshes

to the south. The release schedule through these structures should be

dependent entirely upon management requirements for marshes, estuarine

nursery, and oyster grounds.

An integral part of the surface water management plan is the direct

reduction of salt water influx by whatever means are warranted. At present,

a number of tidal weirs are in operation for the purpose of marsh manage-

ment. Extension of this network across major tidal channels should be

encouraged.

Of major significance with regard to salt water intrusion is the

deterioration of the barrier islands. The increase in cross-sectional

area serving the exchange of water between the estuaries and the Gulf,

together with diminishing protection from wave action and storm surge,

greatly enhance salinization. Maintenance of the barrier islands is a

fundamental part of the water resource management plan.

Environmental Engineering

When coastal Louisiana was in a virgin condition, nature did a

superb job of environmental management. Balanced environmental condi-

tions resulted in high biological productivity, and, in general, the

system was self-maintaining. Erosion occurred along some parts of the

coast, but this was more than compensated for by the new land built in

the vicinity of the active outlets of the river.

Man's impact has caused serious imbalance in the system. One symptom

is massive marsh deterioration and land loss. Land in the coastal area is

being lost at a staggering rate of 16.5 square miles per year and a 30 year

loss of almost 500 square miles has been measured. It is not an exaggera-

tion to say that the delta is dying.

We must restore the delta and manage it to optimize natural produc-

tivity. This can be achieved by directing natural processes. For example,

the freshwater outflow and transported sediment load represent a tremen-

dous amount of energy and supply of materials. The delta has literally

been constructed by this energy source and material supply. By redirecting

flow and helping the river to initiate new cycles of delta building, new

marsh lands and estuaries can be built.

The most favorable locales for controlled delta building are along

the lower reaches of the Mississippi River and the outlets of the

Atchafalaya River in Atchafalaya Bay. Even though these areas are

marginal to the present study area, secondary effects resulting from

changes in outflow and sedimentation patterns would have profound effects

throughout the coastal zone.

The Atchafalaya has been building a marine delta lobe since about

1950 and if not interrupted, some 100 square miles or more of new marsh

land will have been added to the coast by the year 2000 (Garrett et al.,

1969; Shlemon, 1972). Similarly, for relatively small investments of

flow and sediment, very large areas of land could be constructed along

the lower Mississippi River in relatively short periods of time (20-50

years). Based on average rates of deposition in modern subdeltas@' it

has been shown that for an annual investment of 5.8 percent of the

Mississippi flow including 17.9 million tons of sediment, an average
land gain of 0.57 mi2/yr could be anticipated at four sites between

Quatre Bayou Pass and Grand Pass (Gagliano, Light and Becker, 1971).

The places at which controlled fresh water diversion structures

intersect development corridors provide exceptional opportunities for

environmental engineering and creative planning. A schematic configur-

ation for such a location is presented in Fig. 5-3. Proportions are

taken from the Myrtle Grove area in Plaquemines Parish along the west

bank of the Mississippi River. As shown in the figure, a diversion canal

would cross the corridor and would provide the conduit for supplementary

water introduced into the flood basin area. Flow would be regulated by

a control structure. At the basin side of the corridor, the diversion

canal would open into a stilling lagoon where, upon abruptly losing

cut
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---p-,'ure 5---3. Schematic plan for environmental management and land use at intersection of
freshwater drainage canal and development corridor.

velocity, the diverted water would deposit the coarser fractions of its

transported sediment load. In all probability, a silt fan would form in

the vicinity of the canal mouth. A small maintenance dredge would period-

ically remove this silt and discharge it through tail pipes into compart-

mented silt reserve ponds along the stilling lagoon margin. Here, the

dredge slurry would be de-watered and used for construction purposes. The

stilling basin would extend parallel to the riverand development corridor,

becoming narrower with increasing distance from the diversion canal mouth.

This zone would also be designated as a pipeline corridor and initial dredg-

ing might be done in conjunction with pipeline construction. In those

areas requiring maintenance dredging, the pipelines would be laid at

sufficient depth so that they would not be damaged by dredging.

The flood basin side of the lagoon and canal system would interface

directly with wetlands. Here, the artificial introduction of sediment-

laden river water would recreate conditions like those which formerly

existed along natural levee backslopes. Such a situation is ideally

suited for cypress-tupelo gum swamps. Cypress could be planted initially

and would propagate itself under managed overflow conditions. Small over-

flow streams would meander through the overflow swamps providing ingress

into flood basin marshes, both for supplementary water and for sportsmen

and other visitors.

The development corridor itself should be reinforced with a major

highway system on or in the immediate vicinity of the back flood pro-

tection levee. The flood protection area within the corridor, situated

on the relatively firm natural levee ridge, would be developed for urban,

industrial and recreation uses. This type of configuration not only

provides for good use of renewable resources, but also takes maximum

advantage of environmental opportunities for growth and development.

Unit planning of multi-functional structures, such as highways and flood

protection levees, or bridges and control structures, will often yield

a savings in cost, environmental impact, and land dedication. This kind

of arrangement has specific application along the banks of the Mississ-

ippi River and along a number of other major freshwater channels.

Erosion control is fundamental in the coastal zone, but is especially

challenging, as there are over 15,000 miles of land-water interface

in that part of the study area south of the GIWW and much of it is

eroding. One approach to erosion control along the muddy shorelines of

large lakes and bays could be the construction of barrier islands. As

shown in Fig. 5-4 the islands would typically be 1/4 to 1/2 miles in

length and separated from the shore by a shallow lagoon. Passes would

be left between individual islands. The islands would be constructed

around a rigid structural core of interlocking metal sheet piles, concrete

tetrahedrons, or some similar skeletal material. The body of the islands
would be composed of lake or bay bottom sediment supplied by suction dredges

or large drag lines. The seaward edge of the islands would be veneered

with gravel, sand, shell, or some other coarse grain material that would
absorb wave energy. The (tidal) passes would be lined with rip-rap or some

other rigid, erosion-resistant material. A soft edge would be left on the
lagoon side of the islands and would be planted with marsh grass.

Assuming that model studies will show physical feasibility of this
type of erosion protection, it has a number of important advantages even
though it would be relatively expensive. Islands would not only prevent

FISHING PIER ..ROCK JETTY

TIDAL STREAM

C
CO BOAT DO- K

TIDAL PASS
9L
H'
MAR

BARRIER BACKSHORE
TIDAL PASS %
0

FISHING 0 41,
PIER %

Z
....f. \VAG T16AL STREAM

--COGINAL SHORELINE

MARSH

SHELL FRINGING
ROCK JETTY BEACH CREST IMARSHI SHALLOW LAGOON MARSH

FISHING
PIER X BOAT DOCK

ORIGINAL
SHORELINE
ST B 11 L 11 Z I 4G ISPOI
CORE
Z;@ SHELL

S
ETTY
TIA L STREAM._t
, 4w

Figure 5-4. Configuration of proposed man-made barrier islands.

erosion, but would also reduce storm surge without destroying the important
land-water interface along the estuary margin. Marshes and swamps could
be maintained in a natural condition landward of the lagoons. The islands
would not only reduce significantly the erosion problem without damaging

the estuary, but would actually enhance the total environment.

Island construction would create new, more diversified habitats.

These would include beaches, vegetated island crests., lagoon fringing

marshes, tidal passes, and lagoons. Increased recreation opportunities

resulting from this approach are particularly attractive. The beaches and

passes would be ideal for surf fishing and other water contact recreation.

Island backslopes and crests provide picnic areas and camp sites, and lagoons

could function as small boat shelters. The new natural environments could

also provide for wildlife and fish habitats. These would include lagoons
for oyster beds, passes for fin fish and crustaceans, fringing marshes and
lagoons as estuarine nursery areas and habitat for migratory waterfowl,
fringing marshes and regulated island crests as mammal and reptile habitats,
and beaches, passes, and island crests as habitats for shore and wading birds.

As shown on the map, man-made barrier islands should be constructed on

the margins of large lakes and bays in places where the wetlands are of high
value for recreation and/or as nursery areas and wildlife habitat. Typical
applications would be along the margins of Lake Salvador and Little Lake,
where erosion is not only destroying valuable marshes, but also is destroying

a number of archaeological sites.

The barrier islands illustrate an important concept of environmental

engineering. That is, if energy and resources must be expended to solve

a problem, it is often possible to reap additional benefits by creative

planning. Subtle changes in elevation and geometry alter natural processes

to create favorable opportunities for desirable flora or fauna. The same

approach could be applied to the geometry of oil field canals and spoil

disposal sites that might result in environmental enhancement instead of

deterioration for the same expenditure of energy and resources.

Nature may well have provided the study area with unique possibilities

for solving problems of regional waste collection and disposal, possibil-

ities that should be further investigated. The first relates to the

nutrient value to the estuarine system of urban sewage if bacteria can be

eliminated. Pilot studies of marsh enrichment are presently in the planning

stage by environmental scientists at the Center for Wetland Resources. A

second possibility that may be of considerable value concerns the generation

in reaction chambers of methane gas and other usable by-products. Plate 14

shows the presence in the study area of a large number of subsurface salt

domes, several occurring at limited depth. An example of such a dome is

shown in Figure 5-5. . These domes would allow the construction of sub-

surface reaction chambers in the form of solution cavities. We believe

that raw sewage could be introduced into such cavities, and with the

introduction of selected catalysts and temperature control, gas generating

reactions induced.

Salt domes, in addition, offer a unique opportunity for underground

storage. In north Louisiana man-made solution cavities in salt domes are

presently being used on an operational basis for storage of liquid propane.

This aspect of storage may be of considerable value-and have tremendous

potential in view of the proximity of salt domes to the site of a proposed

superport in the west delta area.

100

k If AA
UT 019.0

^4000 F&WT

SALT A LT

&
kop fA 0 0

124wo IF WII-T

14W"P*FT

DIP SECTION STRIKE SECTION

0 3000

FEET

FROM BATES, COPELAND, AND DIXON, 1959
Figure 5-5. Generalized block diagram of Avery Island salt dome- (After
Bates et al., 1959.)

101

Although a discussion of waterways is beyond the scope of this report

when it concerns navigational and economic aspects, these aspects cannot be

separated from coastal zone management. This is especially true when con-

sidering the Mississippi River providing access to the port of New Orleans.

As stated earlier there exists a defined need for supplementary fresh water

and sediment to be introduced into the coastal zone through diversion of

Mississippi River flow. This means that any study dealing with improvements

of deep draft access to New Orleans should consider in depth the degree to

which such improvements will facilitate or impede future implementation of

Mississippi River flow diversion into adjacent estuaries. Particular emphasis

should be placed on developing alternatives for navigational access improve-

ment that would require less discharge for channel maintenance, thus making

this water and transported sediment available for environmental management.

In general, widening and deepening of natural channels and dredging of

canals from the Gulf inland create serious environmental problems. Salt-

water intrusion, accelerated runoff, and increased tidal exchange all

accelerate marsh and swamp deterioration and erosion. For these reasons,

any widening and/or deepening of Barataria Pass as is currently under study

by the U.S. Corps of Engineers would probably have severe environmental

impact on the des-Allemands-Barataria estuary system. In addition, deepening

of Barataria Pass would further disrupt west to east longshore drift of sand

along the Timbalier-Grand Isle barrier complex. Unless provisions for sand

bypassing would be made, this would cause a deficiency in sand nourishment

on Grand Terre Island (Plate 12), and, in turn, would result in accelerated

erosion of the island.

The proposed alignment of the Lafourche Jump channel should be moved to

102

the east where it would become the margin of the Lafourche Development

Corridor. Spoil should be used along the western side of the canal to

prevent salt water from invading adjacent bays and wetlands.

Conflicts

As development of the study area has progressed to the present point

in time without the benefit of a comprehensive planning process, it is

not surprising that there are conflicts in management objectives. It is

important to distinguish between existing projects and land uses which

are only in the planning stage. Obviously, the former represent elements

and factors which are often difficult or impossible to modify, regardless

of their long term undesirable effects. However, in many instances, the

impact of such conflicts can be minimized by engineering modifications or

restrictions prohibiting further growth or development. For example, cul-

verts can be installed through a highway or railroad embankment that disrupts

runoff. Poorly located flood protection levees having detrimental impact on

wiatlands can be breached. Restrictions can be developed to prohibit further

drainage of wetland areas or construction therein.

Conflicts related to projects in the planning stage are easier to

resolve. In many instances, changes in alignment and/or engineering design

may greatly reduce conflicts and make the project compatible with regional

management objectives. A good example is the recent alterations in alignment

and design of Interstate 410 adopted by the Louisiana Department of Highways

following an environmental impact analysis of the highway (Coastal Environments,

Inc., 1973).

Cancellation of a project, even in the final stages of planning after

millions of dollars have been spent in feasibility studies, may still effect

103

a considerable savings in resources and/or dollars. However, the momentum

that a project gains as the expenditure of the planning investment increases

often weightsthe outcome of the decision heavily in favor of the proposed

project, no matter how convincing the demonstration of adverse impact may be.

Another useful classification of conflicts can be made in reference to

the geometry and extent of their impact. Linear conflicts, as the name

implies, may extend for some distances, and may involve more than one

management area. Examples are highways, railroads, pipelines, canals,

levees, and power lines. Localized conflicts would include land reclama-

tion projects, industrial sites, nuclear power plants, offshore platforms,

and jetties. Examples of general conflicts are shell dredging permits,

wetland drainage policy, forestry and agricultural rractices, and disposal

of urban and industrial wastes.

In Plate 22 of the Atlas, an attempt has been made to identify existing

and proposed linear, localized, and general conflicts related to the multi-

use management plan outlined in this report. A number of these projects are

still in the planning stage and could be modified to reduce conflict and

make them more compatible with the proposed plan. Included in this category

are the Larose-Lafitte Highway, the Raceland-Gibson Highway, the Vacherie

Highway, and the LOOP Pipeline and terminal facilities.

A number of proposed projects have very severe environmental implica-

tions and present severe conflicts with the proposed plan. These include

the Louisiana Intracoastal Seaway, deepening of Barataria Pass, and the

proposed Jefferson Parish major street plan.

Dredging and spoil disposal practices of the mineral extraction indus-

tries in general are in direct conflict with the proposed multiuse

104

management plan, as are local and state policies related to reclamation

of wetlands for urb.an, agricultural, and industrial development.

105

SUMMARY AND CONCLUSIONS

Obviously, the implications of the proposed plan are far

reaching. While beneficial to some landowners, many communities, and
the state and the nation in general, implementation would undoubtedly

impose financial and social hardships on a considerable number of

individuals. The emphasis of our studies has been on the environment

and suitability of the landscape for certain uses. Although not considered

here, social, economic, engineering, and legal considerations are

equally important.

The necessary legislation and authority to partially implement

such.a plan may be already in effect. Large public works projects can

be used to reinforce development corridors and to direct growth into

suitable areas. Without indirect subsidy in the form of highways,

flood protection, and drainage, wetland reclamation usually is not

economically feasible. Further documentation of the value of renewable

resources and consumer penalties associated with misuse of wetland areas

will strengthen this argument.

It is fully recognized that private landowners must be compensated

for loss of property rights and revenues, or for participation in

environmental management programs. This has been done in other states

through tax reliefs, scenic and use easements, and direct lease. Public

acquisition is recommended for the most important renewable resource

areas, and unique environmentaland cultural features.

A continuing program of environmental and land use research,

and public education is vital. Systematic ranking and evaluation of

our resources and a public awareness of their value will insure responsible

106

decisions from elected and appointed public officials. It is essential

that the state and local areas gain control of their destinies. Deci-

sions that may result in the deterioration of the environment and the

quality of life of coastal zone citizens cannot be made in distant

corporation board rooms or administrative offices.

We must learn more about the capacity of the region to absorb

increases in population and industry. The natural systems already

exhibit clear signs of imbalance. Rigid control standards must be

imposed on industry. New industry must be compatible with the environ-

mental setting.

Historic studies document that random, unplanned development in

the coastal zone results in environmental destruction by attrition.

Although impact of individual actions may seem insignificant, the

cumulative effects are often of catastrophic proportions. For the past

thirty years, the natural environment of the Louisiana coastal zone

.has seriously deteriorated as a result of the impact of growth and

development. The deterioration is accelerating at an alarming rate.

These historic changes are documented and can be measured,and future

changes, if controls are not imposed, can be predicted with a high degree

of probability.

This study has attempted to develop a spatial framework and some

basic guidelines for mulituse management of south-central Louisiana.

Emphasis is placed on environmental management, but the need for

continued economic growth is also recognized and weighed heavily

in the planning process. Clearly, the plan is not all inclusive, nor

are the lines sacred. The plan has, however, been erected upon a firm

107

data base and follows a methodology that can be tested.

An attempt has been made to keep the plan at a level of resolution

that would be most compatible with the work of other agencies. Hope-

fully it will intermesh with the efforts of the various regional, parish,

and municipal planning offices as well as those of other local, state,

and federal agencies.

It should be emphasized that planning is a process and a specific

plan is only a summary of the status of the process at a particular

time. For this reason, the study should be regarded as open-ended.

The Atlas has been designed so that additional sheets may be issued at

future dates. Hopefully, these additions will not only present new

data,, but will also show more specific versions of the plan as the level

of effort is progressively focused to smaller and smaller units.

The approach developed and recommendations made for the study

area should have broader applications in the state of Louisiana, as well

,as in other coastal regions.

108

APPENDIX A

FLIGHT LINES AND DATA SUMMARY

REMOTE SENSING MISSIONS

OVER 1
4
BARATARIA-TERREBONNE AREA

109

- -------- --------------------- .00o L6
.0006 OCoO6
Sall,

----------------
-----------------------------------------------------

-0
.4'a --r.
------------------------------------ ---------------------------
A V9 n27?IVJ
9 0

Vil YNMOU.988.91

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

m I/z A ----------
All
lp
A-Z

L/v

8ZI/179L . . .. . ...........

8ZI/691

8ZL/99t

C9Z/V6L

8ZL/V6[

NOISSIW

;ji
Rif

TABLE 1B

INSTRUMENT SUMMARY, MISSISSIPPI DELTA

MISSION 154/TEST SITE 128 110/23/70 IFLIGH 6 JAIRCRAFT
Q; 4-4U
z w M SENSOR RC-8/1 RC-8/2 Hass 1 Hass 2 Hass 3 Hass 4 Hasa-.-5-Hass-6
FOCAL LEN.
FILM SO 397 SO 246 2402 2402 2402 2402 2424 2402
w FILTER Cl. AV 0.7 pm 47B 58 25 A 2E+38 89 B 21 + 57
z E-4 z ROLL NO. 38 39 24 25 26 27 1 28 1 29
@4
5 1 6.3 Bayou Moreau to Lake Inferme Gas Field.
7 1 6.3 Pelican Point through Grande Isle into Gulf of Mexico.

Fj
MISSION 154/TEST SITE 128 1 10/21/70 FLIGHT 3 1 AIRCRAFT
ROLL NO. 4 18 19 1 20 1 21 1-22 1 23
5 1 6.0 Reflown.

Reflown. Bayou Moreau to Ground Lake.
5 1 6.0
7 1 6.0 Reflown. Bayou Cholas through Grande Isle to Gulf of Mexico.

TABLE 2A

TEST SITE AND OPERATIONS SUMMARY

MISSISSIPPI DELTA/BARATARIA BAY

Test Site - 128 Principal Investigator
Dr. W. G. McIntire

Flight Operations

Barataria Bay

1. 2 flight lines - 2 altitudes (6000 and 3000 feet).
2. 3 flights required - flooding tide, ebbing tide, and night
flooding tide.
3. Strobe lights at each end of Line 5 at night.
4. Line 5 only line to be flown at Barataria at night.

TABLE 2B

INSTRUMENT SUMMARY, MISSISSIPPI DELTA/BARATARIA BAY

4; WU MISSION / TEST SITE I IFLIGH 1AIRCRAF
z r. z C;7 SENSOR RC 8 RC 8 Hass 1 Hass 2 Hass 3 Hass 4 Hass 5 Hass 6
0 rf 0 0
t-4 --7-- 7T -in. 70 4 0 ;;T- -0-m-m W -mm 7U -mm 77-m-m
@4 o -q En w FOCAL LEN. 6 in. rm
r. I--, H -
.'j FILM S0246 2443 2448 2443 2402 2402 2402 2424
W FILTER 0.70 0.52 HF 3 15 47 B 58 25 89 B
W
z E-4
@-q -<4 %-@ ROLL NO. 36 37 38 39 40 41 42 43
@4 P-4 H @4 - I--
90 30' N 290 07' N East of Bay Marchand to north of Round Lake. Magnetic heading
4 @00 08' W 900 04' W 5.9 22 of 3550.
*5 1 290 29' N 290 25' N South of Turtle Bay to northeast of Golden Meadow.
900 09, W 900 12' W 5.9 6
*5 2 same as same as Southeast of Golden Meadow to Turtle Bay, then west to north Little
line5/1 line 5/1 2.9 6 Lake. Magnetic heading 0350.
same as same as Same coverage as Line 4/Run 1, using magnetic heading 1750.
4 2 1line 4/1 line 4/1 2.9 22
*5 3 same as same as 0 Not plotted. Same as Line 5/Run 2.
line 5/1 line 5/1 0 6.0 6
same as same as @4 Not plotted. Same as Line 5/Run 2. Magnetic heading 2150.
5 4 line 5/1 line 5/1 -FX4 3.0 6

*Extra flights flown 3/5/71.

TABLE 3A

TEST SITE AND OPERATIONS SUMMARY

MISSISSIPPI DELTA/BARATARIA BAY

Test Site - 128 Principal Investigator
W. G. McIntire
Application Discipline
Hydrology Site Coordinator
L. D. Wright/
Organization W. G. Smith
Coastal Studies Institute
Louisiana State University Mission Manager
Baton Rouge, Louisiana 70803 Frank Newman

INVESTIGATION OBJECTIVES
Barataria Bay
To monitor (on a seasonal basis) vegetational changes and erosion
along the shoreline of small lakes and bays that contribute to land loss
and coastal deterioration.

To obtain information on turbidity characteristics of coastal
water bodies.

To relate these data to environmental factors currently under
study by Louisiana State University Sea Grant and Coastal Studies
Institute researchers.

Flight Operations
Barataria Bay
1. 2 flight lines - two altitudes (15,000 and 3,000 feet).
2. 2 flights required - one daytime and one night slack tide.
Strobe lights at each end of Line 5 at night.
3. Only Line 5 to be flown at Barataria Bay at night.

113

TABLE 3B

INSTRUMENT SUMMARY, MISSISSIPPI DELTA/BARATARIA BAY

MISSION 165/ TEST SITE 128 5/16/71 IGHT I AIRCRAF NC130B
C;7 :@l SENSOR RC 8 RC 8 KA 62/3 KA 62/&KA 62/-
0 rj 0 0 P
F-4 0 @4 -4 FOCAL LEN. 6 in. 6 in. 3 in. 3 in. 3 in.
r. 1-% FILM 2424 2443 S0397 2402 2402
W a) F1 FILTER 89 B W 12 N A 25 A 47 B
z 9 z '-' I
H H H IROLL NO. 1 1 2 1 3 1 4 5
F4 H @4 1
90 08' N 290 29' N Bayou Moreau, off coast, to Little Lake. Magnetic heading 3340.
4 1 00 05' W 90010, W 15.1 30
90 29' N 290 26' N
5 1 ri
00 09' W 900 12' W 15 1 10 Little Lake to Golden Meadow. Magnetic heading of 2410.
0
0

X,
5 2 same same 4J 3 10 Same area as Line 5/1. Magnetic heading of 2390.
4 2 W 3.1 30 Same area as Line 5/1. Magnetic heading of 1680.
same same

Flooding Tide. Data correction starts approximately 3 hours before high tide.

TABLE 4A

TEST SITE AND OPERATIONS SUMMARY

LOUISIANA UPPER DELTAIC PLAIN

Test Site - 253 Principal Investigator
S. M. Gagliano
Application Discipline
Geography @Site Coordinator
R. E. Becker
Organization
Louisiana State Universtiy
Baton Rouge, Louisiana 70803

FLIGHT OBJECTIVES
The objectives of the flight are to support an investigation to
develop schemes for comprehensive water resource management and use
inventory which will be of value in operational programs of the
Corps of Engineers. The overflight will acquire small-scale
multispectral photography which will be used to develop methods for
regional land use and hydrologic patterns of the upper Louisiana
Deltaic Plain during a season when vegetal ground cover is at a
minimum.

115

TABLE 4B

INSTRUMENT SUMMARY, LOUISIANA UPPER DELTAIC PLAIN

94( TEST SITE 253 1 3/16/72 RB57F
MISSION IFLIGH 1 1AIRCRAF
c; 44
;4 M SENSOR _ RC8/4R1 RC8/4L Hass 1 Hass 2 Hass 3 Hass 4 Zeiss Hass 5
0 .,.q 0 0 E-1-
@4 @4 H C/) to FOCAL LEN, 6 in. 6 in. 40 mm 40 mm 40 mm 40 mm 12 in. 40 mm
FILM SO 397 2443 2402 402 2424 SO 356 SO 397 2443
FILTER
cu 2A 510pm 25 A 57 89B N/A 2 A 12+JOB
z %-0 z
i-J ROLL NO. 1 2 4 5 6- 7 3 8
@-4 P4 @4 E, @4 I - I
1 1 1290 58'.5 290 57'.5 Beaumont, Texas to Napoleanville, Louisiana.
2a 900 58'.8 940 01'.3 60 276
lb 1 1 1290 47'.3 290 47'.7 60 1 276 Weeks Island, Louisiana to Chandeleur Sound.
910 41'.8 890 10'.3
290 55'.3 790 50'.7
2b 1 60 276 Drum Bay to Lake Verret.
890 17'.5 910 10'.2
Extra 1 300 01'.0 290 34'.7 60 3 miles Northwest of New Orleans to 10 miles south of New Orleans.
900 15'.2 900 02'.5

TABLE 5A

TEST SITE AND OPERATIONS SUMMARY
MISSISSIPPI DELTA/BARATARIA BAY/ATCHAFALAYA BAY

Test Site - 128/253 Principal Investigator
W. G. McIntire
Application Discipline
Oceanography Site Coordinator
R. E. Becker
Organization
Louisiana State University
Coastal Studies Institute
Baton Rouge, Louisiana 70803

FLIGHT OBJECTIVES
1. To map regional patterns of outflow and effluent dispersion
from all Mississippi River distributaries (including the Atchafalaya).

2. To correlate with winds, tides, and seasonal factors including
river stage and precipitation budget.

3. To calibrate plume areas with gaged discharge at Vicksburg,
Mississippi (total flow) and Simmesport (Atchafalaya flow).

GROUND REQUIREMENTS
Ground truth - temperature, salinity, and wind observations will
be performed at Grand Isle and Atchafalaya Bay during overflight.

117

TABLE 5B

INSTURMENT SUM@ARY, MISSISSIPPI DELTA/BARATARIA BAY/ATCHAFALAYA BAY
MISSION 194 / TEST SITE 128/24 3/17/72 IFLIGHT 3 1AIRCRAFT RB57F
t4-4 Zeiss Has -
M SENSOR RCSAR RUAL s 1 Hass 2 Hass3 Hass 41Hass 5
0 .,1 0 0 p e@
r-1 cn rA FOCAL LEN. 6 in- 6 in, 12 in 40 mm, 40 mm 40 mm 40 mm 40 mm
FILM ;0 39Z 2443 SO 397 2402 2402' 2424 So 356 2443
bo
FILTER 2 A 510 pm 57 25 A 89 B N/A 12+30B
ROLL NO. 12 13 1 14 15 1 16 17 18 19
@4
290 02'.4 290 02'.4 From 25 miles east of Garden Island Bay to 40 miles west of Caillou
1 1 88 0 411.0 91 043'.0 60 140 Rav- Louiginna,
2 1 290 13'.3 290 14'.2 60 140 From 10 miles southwest of Point Au Fer Island to 20 miles east of
910 23'.8 880 42'.7 Delta National Wildlife-Refuge.
290 25'.5 290 24'.6 5 miles east of Breton Island to 5 miles South of Marsh Island.
3 1 60 140 From 2
00 880 46'.8 910 42'.3
290 39'.1 290 37'.4 60 140 White Lake to 15 miles southeast of Chandeleur Islands.
4 1 920 32'.2 880 37'.3

APPENDIX B

AGENCIES AND GROUPS CONTACTED DURING STUDY

User input for this study was obtained through personal interviews,
attendance of public hearings, participation in meetings and lectures
to special interest groups. Primary lectures and contacts are listed
below.

Oral Presentations

American Public Works Association. New Orleans City Planning Commission
in New Orleans, February 17, 1972.

Environmental Problems in the Louisiana Coastal Zone. Sierra Club Chap-
ter Wide Conference, Bunkie, Louisiana, February 20, 1972.

Coastal Zone Management Techniques. Louisiana Coastal Marine Resources
Commission, March, 1972.

A Positive Approach to the Environment in Coastal Louisiana. Louisiana
Intracoastal Seaway Association, Lafayette, Louisiana, April 8,
1972.

Environmental Enhancement through Controlled Sedimentation in the Missis-
sippi Delta. Symposium*on Sedimentary Environments, Society for
Economic Paleontologists and Mineralogists, Environmental Research
Group, Denver, Colorado, April 16, 1972.

General Impact of Plans and Proposals that Affect Estuary System in
Louisiana. Student Government Assn., Dept. of Environmental
Affairs, LSUNO, April 22, 1972.

Coastal Zone Planning and Development. LSU Sea Grant Program, Baton
Rouge, La., May 9-10, 1972.

Guest Lecture * Southeastern Louisiana University, Hammond, La., June
27, 1972.

Environmental Management in Coastal Louisiana. Mobil's Environmental
Conference, New Orleans, Louisiana, Sept. 6-7, 1972.

Panel Discussion on 1-410. New Orleans Group of the Sierra Club, Sept.
10, 1972.

Encroachment of Urban Development on Wetlands in the New Orleans Area.
Orleans Audubon Society, Sept. 18, 1972.

Environmental Analysis for Coastal Zone Planning and Urban Encroach-
ment in the New Orleans Area. LSU Sea Grant/Industry/Government
Program, Baton Rouge, La., Sept. 30, 1972.

119

Toward Environmental Management of the Louisiana.Coastal Zone. Sierra
Club, Baton Rouge, La., Oct. 22, 1972.

Environmental Problems in Coastal Louisiana. Louisiana Attorney General's
Environmental Advisory Committee, Baton Rouge, La., Oct. 26, 1972.

Proposed Management and Development Plans. RUBY Conference for Louisi-
ana Wetlands, Environmental Management Research Lab, Oct. , 1972.

Changes to the Environment that Progress Has Brought. Consulting Eng-
ineers Council of Louisiana, Inc., New Orleans, La., December, 1972.

Man's Impact on Marshlands. AAAS Symposium, Washington, D. C., Dec., 1972.

Urban Growth in Louisiana Wetlands. Castle Manor Improvement Assn., Inc.,
New Olreans, La., January 16, 1973.

Public Works and Urban Growth, Transportation. Latin American Studies
Institute, LSU, Baton Rouge, La., Feb. 22, 1973.

Coastal Zone Resources and Management. Soil Scientist Workshop, Alex-
andria, La., Feb. 27, 1973.

Environmental Management in Coastal Louisiana. Lafayette Rod and Gun
Club, Lafayette, La., Nov. 10, 1973.

Environmental Problems in Coastal Louisiana. RUBY Conference for Louisiana
Wetlands, Baton Rouge, La., Nov. 17, 1973.

Persons and Organizations Contacted

Robert Alonzo
Castle Manor Civic Association
4683 Galahad Dr..
New Orleans, La.

Charles Anderson
Plaquemines Parish Mosquito Control
Braithwaite, Louisiana 70040

Bob Angers, Jr.
Editor, Publisher of the Acadiana Profile
P. 0. Box 52247
Oil Center Station
Lafayette, Louisiana 70501

P. A. Becnel, Jr.
Chief, Hydraulics Branch
Engineering Division
New Orleans District, Corps of Engineers
P. 0. Box 60267
New Orleans, Louisiana 701@O

120

Vernon Behrhorst Dr. Frederic G. Deiler
Executive Vice-president Freeport Sulphur Company
Louisiana Intracoastal Seaway Assn., Inc. P. 0. Box 61520
Box 2, USL Station New Orleans, Louisiana 70161
Lafayette, Louisiana 70501
W. K. Dornbusch, Jr.
Henry Bernhardt, Jr. Geology Branch
Iberia Rod and Gun Club U. S. Army Corps of Engineers
New Iberia, Louisiana 70510 Waterways Experiment Station
P. 0. Box 631
Charles Bosch Vicksburg, Mississippi
Louisiana Wildlife Federation
2889 Plank Road Vernon Dowdy
Baton Rouge, Louisiana 70801 Louisiana-Arkansas Division
Mid-Continent Oil and Gas Assn.
Dr. Donald Bradburn 519 Fidelity Bank Building
Sierra Club, Delta Chapter Baton Rouge, Louisiana 70801
465 Audubon St.
New Orleans,, Louisiana 70118 Joe Dykes
Plan Formulation Branch,
Bob Brookshire Planning Division
Louisiana-Arkansas Division U. S. Army Engineer District,
Mid-Continent Oil and Gas Assn. New Orleans
519 Fidelity Bank Building P. 0. Box 60267
Baton Rouge, Louisiana 70801 New Orleans, Louisiana 70160

Frederic M. Chatry Gerald Dyson
Chief, Basin Planning Branch Louisiana Department of Public Works
U.S. Army Engineers, New Orleans District Capitol Annex
P. 0. Box 60267 Baton Rouge, Louisiana
,New Orleans, Louisiana 70160
J. B. Earle
Jack 0. Collins State Conservationist
Louisiana Wild Life and Fisheries Commission Soil Conservation Service
Opelousas, Louisiana 70570 U. S. Dept. of Agriculture
P. 0. Box 1630
Daniel V. Cresap, Alexandria, Louisiana 71301
Chief Engineer
State of Louisiana La Terre Company, Inc.
Department of Public Works DuLarge Route
P.O. Box 44155 Box 206
Capitol Station Houma, Louisiana 70360
Baton Rouge, Louisiana 70804
Honorable C. J. Egan
Ed Crowley Jefferson Parish Council
New Orleans City Planning Commission New Gretna Courthouse
New Orleans City Hall Gretna, Louisiana 70053
New Orleans, Louisiana
Frank Ehret
Gladney Davidson Citizen's Committee Jean Lafitte
Department of the Interior National Cultural Park Commission
Bureau of Sport Fisheries and Wildlife 5048 Ehret Route
Atlanta, Georgia Marrero, Louisiana 70072,

121

Jack V. Eumont Charles Guice
Louisiana Land and Exploration Co. Gulf of Mexico, Outer Continental
New Orleans Office Shelf Office
Suite 200 Bureau of Land Management
225 Barronne St. 3200 Plaza Tower
New Orleans, Louisiana 1001 Howard Ave.
New Orleans, Louisiana 70113
Bres Eustis
Eustis Engineering Company Gulf States Marine Fisheries Commission
3011 28th St. 521 St. Louis St.
Metairie, Louisiana 70002 New Orleans, Louisiana 70130

Linda Freedman Honorable William Guste
State Planning Office Office of the Attorney General
New Orleans, Louisiana State Capitol Building
Baton Rouge, Louisiana 70804
Hugh Ford
Jefferson Parish Planning Commission Col. Herbert R. Haar
P. 0. Box 9 Assistant Port Director
Gretna, Louisiana 70053 New Orleans Dock Board
New Orleans, Louisiana 70160
James Friloux
Environmental Protection Agency John Hammond
Bay St. Louis, Mississippi Assistant Professor
Urban Studies Institute
Charles Fryling Louisiana State University at
Dept. of Landscape Architecture New Orleans
212 Long Field House New Orleans, Louisiana
Louisiana State University
Baton Rouge, Louisiana 70803 Hadley Harrison
Louisiana Dept. of Public Works
B. J. Garrett State Land Office
Hydraulics Branch, Engineering Division Baton Rouge, Louisiana
U. S. Army Engineer District, New Orleans
P. 0. Box 60267 Joe Herring
New Orleans, Louisiana 70160 Louisiana Wild Life and Fisheries
Commission
Dr. Jon L. Gibson Quail Drive
Department of Social Studies Baton Rouge, Louisiana
University of Southwestern Louisiana
Lafayette, Louisiana 70501 Marc Hershman
Louisiana Commission for Coastal
Dr. Leslie Glasgow and Marine Resources
Forestry Building Sea Grant Legal Program
Louisiana State University 52-60 LSU Law Center
Baton Rouge, Louisiana 70803 Baton Rouge, Louisiana 70803

Dennis Grace Oliver A. Houck
New Orleans Dock Board National Wildlife Federation
P. 0. Box 60046 1412 Sixteenth St. N. W.
New Orleans, Louisiana 70160 Washington, D. C. 20036

122

Dr. Leo Hough Honorable Gillis W. Long
State Geologist Louisiana Superport Task Force
Louisiana Geological Survey 29th Floor, International Trade Mart
Geology Building New Orleans, Louisiana 70130
Louisiana State University
Baton Rouge, Louisiana 70803 Louisiana Land and Exploration Company
Suite 12001 225 Barronne St.
Lloyd C. Irland P. 0. Box 60450
U. S. Dept. of Agriculture New Orleans, Louisiana 70160
Forest Service
Southern Forest Experiment Station Louisiana Shrimp Association
701 Loyola Ave. P. 0. Box 10303
New Orleans, Louisiana 70113 New Orleans, Louisiana 70121

Harold Katner Louisiana State Historical and Cultural
New Orleans City Planning Commission Commission
City Hall Old State Capitol Building
New Orleans,, Louisiana Baton Rouge, Louisiana

E. Burton Kemp Louisiana Wild Life and Fisheries Commission
Foundations and Materials Branch 400 Royal Street
Engineering Division New Orleans, Louisiana 70130
Crutcher-Tufts Building
3545 Interstate 10 Bob Lozano
Metairie, Louisiana Louisiana Archeological Society
New Orleans, Louisiana
Dr. Charles Kolb
Geology Branch W. L. Manning
U. S. Army Corps of Engineers Superintendent, Marine
Waterways Experiment Station Louisiana Land and Exploration
P. 0. Box 631 P. 0. Box 231
Vicksburg, Mississippi Houma, Louisiana 70360

Dr. E. L. Krinitzsky J. Ben Meyer, Sr.
Chief,, Regional Studies Section Plaquemine Parish Historian
Geology Branch Braithwaite, Louisiana
U. S. Army Corps of Engineers
Waterways Experiment Station Miami Corporation
Vicksburg, Mississippi 410 N. Michigan Ave.
Chicago, Illinois 60611
Robert A. La Fleur
Water Polluting Control Division P. J. Mills
Dept. of Wildlife and Fisheries Deep Draft Harbor and Terminal Authority
P. 0. Drawer F. C. 1130 International Trade Mart
University Station New Orleans, Louisiana 70130
Baton Rouge, Louisiana
Mineral Board, State of Louisiana
George Landry Third St. and North Blvd.
Louisiana Dept. of Highways Baton Rouge, Louisiana
Baton Rouge, Louisiana

123

D. D. Modianos Gordon Pfleuger
Assistant General Superintendent Jefferson Parish Planning Commission
New Orleans Sewage and Water Board Eastbank Courthouse
City Hall Metairie, Louisiana 70001
New Orleans, Louisiana
Picciola and Associates, Inc.
Wayne Mooneyhan P. 0. Box 758
Earth Resources Laboratory Galliano, Louisiana 70354
Mississippi Test Facility
Bay St. Louis, Mississippi 39520 Richard C. Plater
Acadia Plantation
Honorable Helen Bryan Moore Thibodeaux, Louisiana
State Land Office
State Resources Building Ory G. Poret
Baton Rouge, Louisiana 70804 State Land Office
Baton Rouge, Louisiana
Dr. Carolyn R. Morillo
President James A. Prunty
Orleans Audubon Society Mobil Oil Company
New Orleans, Louisiana Exploration and Producing Division
1001 Howard Ave.
Andre Neff New Orleans, Louisiana 70113
St. Bernard Parish Planning Commission
St. Bernard Parish Courthouse Annex Bill Reed
Chalmette, Louisiana 70043 Louisiana Offshore Oil Port
Oil and Gas Building, Rm. 950
Dr. Robert W. Neuman 1100 Tulane Ave.
L.S.U. Museum of Geosciences and Man New Orleans, Louisiana 70112
19 Atkinson Hall
Louisiana State University J. F. Roy
Baton Rouge, Louisiana 70803 Regional Planning Branch, Planning
Division
Patrick Noonan U. S. Army Corps of Engineers
Nature Conservatory New Orleans, Louisiana
1800 North Kent St.
Arlington, Virginia 22209 Dr. Lyle S. St. Amant
Louisiana Wild Life and Fisheries
Charles F. O'Doniel, Jr. Commission
Regional Planning Commission 400 Royal St.
Jefferson, Orleans, St. Bernard, New Orleans, Louisiana 70130
St. Tammany
Suite 900 Dr. Roger T. Saucier
Masonic Temple Building U. S. Army Engineer
333 St. Charles Ave. Waterways Experiment Station
New Orleasn, Louisiana 70130 P. 0. Box 631
Vicksburg, Mississippi
Michael Osborne
Sierra Club, Delta Chapter R. H. Schroeder, Jr.
New Orleans, Louisiana Plan Formulation Branch, Planning
Division
Dr. William Palmisano U. S. Army Corps of Engineers
Forestry and Wildlife Management School New Orleans District
101 Forestry Building P. 0. Box 60267
Baton Rouge, Louisiana 70803 New Orleans, Louisiana

124

Eddie L. Schwertz, Jr. Robert Tannen
Office of State Planning Curtis and Davis Architects
P. 0. Box 44425 111 Iberville St.
Capitol Station New Orleans, Louisiana 70130
Baton Rouge, Louisiana 70804
Terrebonne Parish Police Jury
Walter Senten P. 0. Box 367
Office of City Planning Courthouse
City Hall Houma, Louisiana 70360
New Orleans, Louisiana
Gary Thomann
W. J. Champine NASA/MSC Earth Resources Laboratory
U. S. Geological Survey Mississippi Test Facility
6554 Florida Blvd. Bay St. Louis, Mississippi 39520
Baton Rouge, Louisiana 70806
Sandra S. Thompson
W. E. Shell,, Jr. Atchafalaya Basin Division
Environmental Resources Branch, Louisiana Dept. of Public Works
Planning Division State Capitol Building
U. S. Army Corps of Engineers Baton Rouge, Louisiana
New Orleans District
P. 0. Box 60267 Richard Troy
New Orleans, Louisiana Office of the Attorney General
234 Loyola
Dr. J. Richard Shenkel 7th Floor
Dept. of Anthropology and Geography New Orleans, Louisiana 70112
Louisiana State University at
New Orleans Marshall K. Vignes
Lake Front La Terre Company, Inc.
New Orleans, Louisiana 70122 DuLarge Route
Box 206
David Slusher Houma, Louisiana 70360
State Soil Scientist
P. 0. Box 1630 Ross Vincent
3737 Government St. Vice-president
Alexandria, Louisiana 71301 Ecology Center of Louisiana, Inc.
932 Phillip St.
George Smith New Orleans, Louisiana
Environmental Engineer
Mobil Oil Company Water Resources Unit
llth Floor, Plaza Towers School of Engineering
1001 Howard Ave. Louisiana State Univeristy
New Orleans, Louisiana 70113 Baton Rouge, Louisiana 70803-

William Clifford Smith Dr. Charles A. Whitehurst
Parish Engineer Technical Director
Terrebonne Parish Police Jury L.S.U. Division of Engineering Research
P. 0. Box 266 Baton Rouge, Louisiana 70803
550 S. Van Ave.
Houma, Louisiana Richard T. Whiteleather
Director, Southeast Region
Claire Stocks U. S. Dept. of Commerce National Marine
Goals for Louisiana Fisheries Service
5339 Colosseum St. 144 First Ave. South
New Orleans, Louisiana 70115 St. Petersburg, Florida 33701

125

Don Whittinghill
Joint Legislative Committee on Environmental Quality
131 Convention St.
Baton Rouge, Louisiana

A. E. Wilder
Consulting Engineers Association of Louisiana
Baton Rouge, Louisiana

126

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