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Point aux Chenes:Past, Present, and Future Perspective of Erosion
by
Charles K. Eleuterius, Ph.D.
G. Alan Criss
Physical Oceanography SectionGulf Coast Research Laboratory
Ocean Springs, Mississippi
December 1991
Prepared for
Mississippi Department of Wildlife, Fisheries, and ParksCoastal Division / Bureau of Marine Resources
Biloxi, Mississippi
ii
Table of Contents
PageList of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
iii
List of Tables
Table Page I. Composition and characterization of sediment samples from Point aux Chenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
iv
List of Figures
Figure Page 1. Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2. Marsh associated with Point aux Chenes Bay . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3. Centralized map of bottom sediments in the study area . . . . . . . . . . . . . . . . . . . 30
4. Wind speed (knots) and direction, January . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5. Wind speed (knots) and direction, February . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6. Wind speed (knots) and direction, March . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7. Wind speed (knots) and direction, April . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
8. Wind speed (knots) and direction, May . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9. Wind speed (knots) and direction, June . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10. Wind speed (knots) and direction, July . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
11. Wind speed (knots) and direction, August . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
12. Wind speed (knots) and direction, September . . . . . . . . . . . . . . . . . . . . . . . . . . 32
13. Wind speed (knots) and direction, October . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
14. Wind speed (knots) and direction, November . . . . . . . . . . . . . . . . . . . . . . . . . . 32
15. Wind speed (knots) and direction, December . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
16. Predicted Tidal Ranges for 1991, Pascagoula, Mississippi. . . . . . . . . . . . . . . . . 33
17. Wave height distributions, January . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
18. Wave height distributions, February . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
19. Wave height distributions, March . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
20. Wave height distributions, April . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
21. Wave height distributions, May . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
v
List of Figures (continued)
22. Wave height distributions, June . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
23. Wave height distributions, July . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
24. Wave height distributions, August . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
25. Wave height distributions, September . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
26. Wave height distributions, October . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
27. Wave height distributions, November . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
28. Wave height distributions, December . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
29. Sediment sampling locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
30. From chart circa 1848 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
31. From chart circa 1860 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
32. From U.S. C. & G. S. Coast Chart No. 189, 1896 . . . . . . . . . . . . . . . . . . . . . . . 38
33. From chart circa 1921 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
34. From aerial photograph of October 27, 1940 . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
35. From aerial photograph of April 30, 1952 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
36. From chart circa 1957 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
37. From aerial photograph of October 20, 1975 . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
38. From chart circa 1978 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
39. From aerial photograph of November 15, 1979 . . . . . . . . . . . . . . . . . . . . . . . . . 41
40. From aerial photograph of April 9, 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
41. From aerial photograph of April 23, 1986 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
42. From aerial photograph of November 21, 1988 . . . . . . . . . . . . . . . . . . . . . . . . . 43
43. TMS pseudo-color image of Point aux Chenes, November 21, 1988 . . . . . . . . 44
44. TMS pseudo-color image of West Point aux Chenes-Bangs Lake, November 21, 1988 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
1
POINT AUX CHENES:PAST, PRESENT, AND FUTURE PERSPECTIVE OF EROSION
Introduction
Substantial losses of natural resources in the southeastern corner of Jackson County,
Mississippi, are occurring directly and indirectly because of coastal erosion. This area of
bays, bayous, and marshes (Figure 1) is comprised of Point aux Chenes Bay, Bangs Lake,
Middle Bay, Bayou Cumbest, Heron Bayou, west Grand Bay, and the contiguous marshes
and uplands with their intricate networks of small bayous, sloughs, and ponds. For
convenience, this coastal marine system will be referred to henceforth herein as simply
"Point aux Chenes". This is Mississippi's last remaining pristine estuary and it has both
economic and social value.
Background
The area supports limited recreational and commercial fisheries. Although access
to the area is somewhat difficult, there are recreational fishing enthusiasts present year-
round. Among the species available to the recreational fishery are sand sea trout (Cynoscion
arenarius), speckled sea trout (Cynoscion nebulosus), red fish (Sciaenops ocellata), Atlantic
croaker (Micropogon undulatus), and flounder (Paralichthys lethostigma). Subsistence
commercial fisheries also exist for these finfish plus shrimp (Penaeus setiferus, Penaeus
aztecus, Penaeus duorarum), crabs (Callinectes sapidus), and oysters (Ostrea virginica).
An extensive accounting of the area's myriad of marine life can be found in Perry and
2
Christmas (1973), Christmas and Langley (1973), and Christmas and Waller (1973). Besides
the marine "fishes", the area is inhabited by other animals.
Among other wildlife are a large number of reptiles and mammals. Eleuterius (1974)
compiled an extensive list of animals that inhabited a slightly larger geographical region
which included Point aux Chenes. Reptiles and herptiles present include turtles,
salamanders, toads, skinks, tortoises, frogs, snakes, lizards, and the American alligator
(Alligator mississippiensis). Mammals that inhabit the area include the nine-banded
armadillo (Dasypus novemcinctus), Atlantic bottlenose dolphin (Tursiops truncatus),
opossum (Didelphis marsupialis), mink (Mustela vison), nutria (Myocastor coypus), raccoon
(Procyon lotor), muskrat (Ondatra zibethicus), and a number of bats. In addition to "fish",
mammals, herptiles, and reptiles, the area is also populated with many species of birds.
Eleuterius (1974) compiled a list of over 300 species of birds for which there had
been reported sightings at Point aux Chenes. While some of the birds are found there year-
round, others are migratory and visit the area only during certain seasons. This marsh-bay-
bayou complex is important to migratory waterfowl. Its value to migratory waterfowl having
been recognized by authorities, it is now a vital component of the North American
Waterfowl Management Plan (Coastal Mississippi Wetlands Initiative Team 1989). Based
on a ten-year survey, Rees (1991) reported that the area north of the former Grand Batture
Islands hosted an estimated 1,000 winter waterfowl annually. However, scientists at Gulf
Coast Research Laboratory, who have spent considerable time in the area during winter,
believe that this estimate for winter waterfowl is low (Lionel Eleuterius, David Burke, John
Caldwell, Personal Communications, October 1991). The authors, who have also made
frequent trips to the area during past winters, agree. Species comprising the greater
percentages of the estimate were redhead (Aythya americana), lesser scaup (Aythya affinis),
American widgeon (Mareca americana), and mallard (Anas platyrhynchos). The extensive
3
marshes are a prime factor in attracting and retaining the large number of animals that
inhabit the area.
The flora of Point aux Chenes has been studied and mapped by Eleuterius (1973).
There are four general types of marshes in Mississippi: saline, brackish, intermediate, and
fresh water. Of the four types, almost all of the marshes in the study area are of the saline
or salt marsh type. According to Eleuterius' research, the saline region (Figure 2) supports
two major marsh plant species; black needle rush (Juncus roemerianus) and smooth
cordgrass (Spartina alterniflora). Both species almost always occur in pure stands, usually
with a common boundary between the two, therefore zonation by these two species is
typified by an abrupt change between them. The S. alterniflora normally forms a fringe
border between the J. roemerianus and the open water of the bays and bayous.
At Point aux Chenes, Spartina alterniflora and Juncus roemerianus grow in their
most robust forms which are characterized by their greater heights and greater densities.
Interspersed with J. roemerianus are some brackish water species; giant cordgrass (Spartina
cynosuroides), saltmeadow cordgrass (Spartina patens), and three-square sedge (Scirpus
olneyi). In addition, scattered throughout the area in special niches in the salt marsh and
uplands are less abundant species including an appreciable number of rare plants (Lionel
Eleuterius, Personal Communication, October 5, 1991).
Indigenous to the "salt flats", i.e. areas with unusually high salinity concentrations
at and near the surface of the substrate, which occur throughout the marsh, especially near
the marsh-forest margin, are a number of other marsh species. On these salt flats are found
glasswort (Salicornia bigelovii), seablite (Suaeda linearis), and saltwort (Batis maritimus).
North of what was once the Grand Batture Islands and around the west margin of Point aux
Chenes Bay, Eleuterius (1971) found extensive beds of the shoal grass, Halodule wrightii.
The rich and diverse flora of Point aux Chenes can be attributed, at least in part, to its
geology.
4
The geological evolution of Point aux Chenes involved a long, complex sequence of
events and processes. Among studies of its geology which served as sources for much of the
geological information synthesized here are those of Priddy and others (1955), Otvos (1973,
1990), Minshew and others (1975), Waller and Malbrough (1976), and Meyer-Arendt and
Kramer (1991). The oldest of the surface deposits found in the area today was deposited
during the mid-Pliocene epoch when an apron of fluvial-deltaic deposits covered the entire
region and coalesced to form the Citronelle Formation. Subsequently, during the
Pleistocene, regional uplift and erosion resulted in elevating and partially removing this
deposit. Early Pleistocene fluvial sediments were deposited in the study area and beneath
the present adjacent Mississippi Sound. Erosion, following this period of sedimentation,
removed much of the early Pleistocene sediments.
With the melting of glaciers and the frozen polar seas near the end of the Pleistocene
Epoch, the sea level rose, inundating the area. The nearshore Biloxi Formation, which
consists of marine deposits, developed during this period of encroachment by the sea as did
the Prairie Formation which was formed from fluvial sediments. As the Earth entered a new
ice age, withdrawal by the sea was accompanied by fluvial deposition along the seaward
margin (Prairie Formation) as it progressed southward. Coastal streams subsequently cut
valleys through the Prairie Formation and other underlying formations. At the peak of this
last glacial period (Wisconsin), the seashore was located approximately 70 miles south of
the present mainland shoreline which corresponds to the present seaward limit of the
continental shelf.
With the increase in sea level near the end of the Pleistocene and early Holocene
times, the sediments which filled the excavated fluvial valleys were of three different types.
Initially, freshwater sediments were deposited which were followed by deposition of
brackish sediments and which, in turn, were followed by marine deposition. Subsequently,
5
marshes and swamps developed behind the mainland shores adjacent to relatively quiescent
waters.
The Escatawpa River, rather than following its present course, i.e. connecting with
the Pascagoula River as a tributary, instead flowed south-southeast and emptied into
Mississippi Sound in the Point aux Chenes Bay-Grand Bay area. The Escatawpa River built
a sizable delta which encompassed all of the study area. Deterioration of this delta began
when the Escatawpa switched course and became a tributary of the Pascagoula River as it
is today. Bayou Cumbest and Bayou Heron, remnants of the former main Escatawpa River
channels, provide little fluvial sediment to Point aux Chenes.
With the change in the course of the Escatawpa River, the seaward transport and
deposit of fluvial sediments, which had formerly offset the sediments lost to erosion, ceased.
Then the abandoned delta of the Escatawpa began to erode away under the sustained attack
by waves under normal conditions, by larger waves that accompany ordinary storms, and by
the great waves and surges of tropical hurricanes. Currents have also played a major role
in the erosion of Point aux Chenes by carrying away the suspended sediments to be
deposited elsewhere and by transporting the sediments as bedload. The winnowing, sorting,
and transporting of sediments by waves and currents resulted in the formation of sandy
barrier islands along the seaward limit of the deteriorating and retreating delta.
Simultaneously, the marshy delta-remnant shores were eroded and retreated northwestward.
The sediment substrate of the marshes is rich in woody-peaty organic material and
mud, but due to the sandy sources of the material that formed this now abandoned delta, the
substrate contains a larger-than-average proportion of sand. Sediments comprising the
marsh substrate are unconsolidated, highly compactible, and contain a large proportion of
water. For foundations, the substrate represents the poorest engineering soil type.
In Mississippi Sound, remains of the Grand Batture Islands and the shoal area once
seaward of them is indicated by the sandy bottom sediments in Figure 3. The greatest clay-
6
mud concentrations are located in the deeper parts of the Sound which are least affected by
waves and currents. This muddy-bottom zone between Petit Bois Pass and Point aux Chenes
is approximately four miles wide at it greatest breadth.
Zones of mixed sandy-muddy bottom deposits up to two miles wide exist between
the predominantly sandy-bottom and the predominantly muddy-bottom areas. They are
found along the margin of the sandy belt skirting the mainland shore, along the sandy-bottom
zone north of the barrier islands, and along the intervening sandy shoals of Petit Bois Pass.
The sediment distribution pattern is the result of prevailing wave and current regimes that
mix, transport, and deposit sediments.
Weather patterns contribute indirectly to erosion at Point aux Chenes. The
subtropical anticyclonic Bermuda High exerts the greatest influence on the climate of the
area. When the Bermuda High intensifies during the spring, it extends its boundaries into
the Gulf of Mexico. This extension into the Gulf results in a shift in the source direction of
the winds to the southeast and south. Wind speeds of spring and summer are normally much
less than those of fall and winter. In early fall, the Bermuda High weakens and its boundary
of influence retreats toward the southeast from the Gulf. Simultaneously with the
withdrawal of the Bermuda High is a southward advance of the continental pressure systems
over the Gulf. As a result of the southward movement of the continental systems, northerly
winds become predominant.
During winter, westerly systems also influence the study area as cold fronts from the
northwest move southward over the Gulf of Mexico. Figures 4-15 from Eleuterius and
Beaugez (1979) show the monthly distribution of winds with regard to direction and speed
for the study area. Generally, the source of the winds during the period October-March lies
between northwest and northeast. The source of the winds during the period April-
September lies between southwest and southeast. The predominant source for all winds
7
during the year lies within the eastern quadrants. Forces associated with tropical storms and
hurricanes also have a profound impact on erosion in coastal areas.
While the principal season for hurricanes in the North Atlantic region is from June
through November, the preponderance of hurricanes occurs in August and September. One-
half of all hurricanes affecting the study area have occurred in September (Eleuterius and
Beaugez 1979). Large wind-driven waves associated with storms and hurricanes, i.e.
forerunners, are responsible for much of the erosion attributed to hurricanes. As they move
into shallower waters, storm surges put into suspension and carry away large amounts of
sediments.
Astronomical tides of the area are those of the adjacent Gulf of Mexico, but modified
by the bathymetry and geometry of Mississippi Sound (Eleuterius and Beaugez 1979). The
tides are primarily diurnal, i.e. usually one high and one low water per day. The principal
diurnal components of the tide are K1, O1, and P1 with periods of 23.93 hrs, 25.82 hrs, and
24.07 hrs, respectively. While the average diurnal range in tide, i.e. the difference in water
levels between consecutive high and low water stages, for Mississippi Sound at Pascagoula
(Figure 16) is 1.5 feet, the overall range in the astronomical tide during a year is
approximately 3.4 feet (National Ocean Service 1991). The tide wave approaches the study
area from the Gulf of Mexico via Petit Bois Pass, spreading outward after entering
Mississippi Sound (Eleuterius 1976, 1979). The maximum tidal current speed of 1 knot (0.5
m/s), calculated for the mouth of bays and passes (Eleuterius 1984), were later observed.
Wind has a profound affect on the tides. When the wind works in conjunction with
the tide, at the flood it drives the water level higher and at the ebb it drives the water level
lower than that prescribed by the tides. When the wind works in opposition to the tide, at
the flood it prevents the water levels from reaching the high and at the ebb it prevents the
water levels from attaining the lows prescribed by the tide. Because of the effect of wind
stress on water levels, the overall range in water elevations during a year exceeds that caused
8
by the astronomical tide-generating forces alone. Large excursions from the predicted
astronomical tide heights for Point aux Chenes occur during strong, sustained winds. The
wind blowing over the water surface is also the generative force for an important class of
progressive water waves, i.e. wind waves or "sea".
Information regarding the wave climate, i.e. the period, height, and direction of
waves, in Mississippi Sound is virtually nonexistent. The monthly distributions of wave
heights as a percentage of time are shown as frequency histograms in Figures 17-28
(Eleuterius and Beaugez 1979). These statistics were generated by the hind-cast method for
the area described by the following coordinates: 28°45'N, 87°30'W; 30°00'N, 87°30'W;
30°00'N, 89°30'W; and 28°45'N, 89°30'W. Although this site lies approximately 25 miles
south of Petit Bois Pass where the heights of waves are generally larger, the wave statistics
should still serve as a reliable relative indicator of the severity of the wave climate within
the study area. Waves during the period October-April, when northerly winds between
northwest and northeast prevail, are larger than in other months of the year. During the
period May-September, the waves, except those associated with stormy weather, are
generally smaller and less steep than those of fall and winter. The winds during this period
are predominantly southerly with their sources lying between southeast and southwest.
Therefore the direction of the wind-generated and waves is northerly. Swells, i.e. waves
generated by the wind but no longer under its influence, are also more prevalent during this
period and also normally approach from between southeast and southwest.
Point aux Chenes, an estuarine system with considerable economic and social value,
is in danger of simply disappearing because of coastal erosion. The goals of this study were
to: (1) determine from available historical and current information the events, forces, and
mechanisms responsible for the area's erosion; (2) determine the rate of erosion and the fate
of eroded sediments; (3) develop scenarios of the erosional processes that incorporate the
9
relevant forces and mechanisms; and (4) forecast the future of Point aux Chenes with regard
to coastal erosion.
Methodology
Assessing erosion at Point aux Chenes from a historical perspective required
synthesizing information and data from disparate sources and interpreting the resulting
aggregate of information. The literature was searched for relevant scientific papers,
scientific reports, and engineering reports. Archives at Gulf Coast Research Laboratory and
at other institutions and agencies were searched for pertinent maps, charts, aerial
photographs, and remotely-sensed imagery.
Because of fiscal constraints, only a select number of maps, charts, and aerial
photographs were chosen from those available for the period 1848-1988. Materials obtained
were those the authors believed would contribute the most toward making an overall
assessment of erosion. First, drawings outlining land masses were constructed by tracing
the shorelines from back-lit photographs, charts, and maps. The land masses on each
drawing were blackened, thereby producing images of the land areas in silhouette. These
silhouette charts were then digitized via an image scanner, imported into a computer, and by
use of computer software, transformed to a common scale for comparative analyses. The
silhouette charts and aerial photographs were studied for the effects of coastal erosion.
Using the set of charts and photographs, shoreline changes were determined at selected sites
by measuring along transects perpendicular to the shoreline. These measurements were used
to estimate the annual rate of land-loss.
Remotely-sensed data acquired by a Daedalus Thematic Mapper Simulator (TMS)
from a NASA ER-2 aircraft on November 21, 1988 were used, primarily, to delineate areas
of water and different vegetative assemblages. The Daedalus TMS, which has the same
spatial and spectral configuration as the Thematic Mapper aboard the Landsat-5 earth
10
resources satellite, is flown at an altitude of 65,000 feet and has a ground resolution of 25
meters. Under certain conditions, different species of vegetation can be distinguished by
their reflected spectral signatures.
The contrast-stretched digital brightness values of the TMS near-infrared band (.76-
.90 :m) were processed using an arctangent function on an Atlas/AGIS software system
(Delta Data Systems). A pseudo-color scale was assigned to the resulting processed
brightness values of the near-infrared band, i.e. 0 to 255. Psueudo-color images were
produced which show an unsupervised classification of the "surfaces" at Point aux Chenes.
To determine the type and composition of sediments at Point aux Chenes, samples
were taken by the authors in 1989 at seven sites (Figure 29). The results of grain-size
analysis of each sample, i.e. each type contribution to sediment composition, were expressed
as percentages of total sample weight.
Aerial photographs of Point aux Chenes were made from an airplane at altitudes of
900 and 700 feet. The aerial surveys enabled the authors to ascertain the present state of the
area with regard to erosion. The small-scale features that are not included on charts and that
do not appear on high altitude photographs were clearly visible from the aircraft. Slides
were made using 35 mm Kodak Ektachrome ISO 400 film and a Nikon camera with a 50mm,
1.4 lens.
11
Results
A single episodic event, a hurricane, brought about conditions conducive to the
acceleration of erosion at Point aux Chenes. However, since charts constructed before or
after the event were not available, the authors relied upon the work of others for establishing
the year of the hurricane event. The hurricane bisected Dauphin Island, thereby forming two
islands. The new island, formerly the west tip of Dauphin Island, was named Petit Bois.
The hurricane-generated cut that separated the new island from the old was, and still is,
referred to as Petit Bois Pass. Otvos (1990) concluded that this bisection of Dauphin Island
occurred between 1740-1766; based on the following references: Governor Cadillac's report
(Kennedy 1976); 1718 charts of DeLisle; 1718-1719 chart of Seur du Sault, 1719-1720 chart
of Serigny, and parts of other French surveys incorporated in the 1732 d'Anville map - all
of which showed Petit Bois Island as part of Dauphin Island. Otvos further cited the report
by Gayarrè who stated that the 1740 hurricane was responsible for washing away roughly
half of Dauphin Island. According to the 1773-1774 charts by Bernard Roman, a wide
passage existed at that time between Dauphin and Petit Bois. This breach, which has since
grown in width, allowed the larger waves generated in the Gulf of Mexico to enter
Mississippi Sound and attack the mainland shores including those at Point aux Chenes.
Grand Batture Island was developed by the reworking of the delta sediments by
waves and currents during the interim from the time of the change in the course of the
Escatawpa River to 1848 (Figure 30). The major axis of the island in 1848 was oriented
roughly northeast-southwest (40°-220°). The elongated barrier island sheltered Point aux
Chenes Bay, Grand Bay, and Middle Bay from attack by northerly-directed waves from
seaward. Personal observations indicate that the island was of low vertical relief and
vegetated by only brush and grass (Lionel A. Eleuterius 1956).
Comparison of the 1848 chart (Figure 30) with that for 1860 (Figure 31) revealed that
notable changes in the area occurred over the 12 year period. Storm surges and waves
12
associated with the hurricanes of 1852, 1856, and probably that of 1860, which made landfall
in the vicinity of Mobile, Alabama, reduced the elevations of Grand Batture Island while
simultaneously increasing its width via overwash. The storms and hurricanes also made
other changes. The islets north of the elongate, northwest-southeast oriented marsh islet and
north of and in close proximity to Grand Batture Island as well as islets within Middle Bay
and Grand Bay disappeared. The marsh area north of and connecting with the middle of
Grand Batture Island developed twin, eastward-oriented peninsulas.
Erosive processes during the 36-year period between 1860 (Figure 31) and 1896
(Figure 32) further altered Grand Batture Island by reducing its width and recurving its
southwest end. The tongue-like extensions of the marshes in Point aux Chenes Bay, Grand
Bay, the south shore of Middle Bay, and near the north shore-center of Grand Batture Island
became much narrower and, overall, smaller in size. The "birth" of some islets, widening
of others, and the formation of shoals as evidenced by the 1896 chart (Figure 32) were
probably the result of overwash. The sixteen hurricanes and tropical storms that occurred
during the 36-year period most likely contributed substantially to the erosion. Hurricanes
and storms, which crossed the coastline close enough to have caused erosion, occurred in:
1870, 1872, 1875, 1877, 1879, 1880, 1881, 1882, 1885 (2), 1887 (2), 1889, 1893, 1894, and
1895. The hurricanes of 1887, 1893, and the storm of 1895 made landfall at Pascagoula,
Mississippi.
During the 25 years between 1896 (Figure 32) and 1921 (Figure 33), erosion brought
about dramatic changes in the land masses. By 1921, Grand Batture Island was no longer
a single island, but had become fragmented into several islands. The remnants of the island
thus became known as the Grand Batture Islands. Figure 33 clearly shows that appreciable
erosion of the islands and peninsulas within Grand Bay had occurred. During this period,
the remnant of Grand Batture Island lying seaward of Grand Bay was reduced in size. The
long narrow, northeast-southeast oriented marsh island on the east side of Point aux Chenes
13
Bay became much narrower than before. Erosion of the marsh island, now known as South
Rigolets Island, had left it with a highly irregular shoreline. The seaward shoreline, where
once the approximate center of Grand Batture Island was located, retreated toward the
northwest approximately one-fourth mile. The breaching of that portion of Grand Batture
Island lying southeast of Point aux Chenes Bay permitted the entry of waves into the Bay
from a southerly direction. The erosion of the north shoreline of Point aux Chenes Bay by
wave action is apparent in Figure 33. During this period, 5 tropical storms and 7 hurricanes
made landfall near enough to have caused appreciable erosion. Two of the hurricanes,
occurring in 1904 and 1906, made landfall at Pascagoula, Mississippi.
Comparisons made between the 1921 chart (Figure 33) and the aerial photograph of
1940 (Figure 34) reveal the magnitude of the coastal erosion that took place over that period
of time. Almost all of the remnant islands that formed as the result of the multiple breaching
of Grand Batture Island were, by 1940, reduced to half their 1921 dimensions. The islands
and peninsulas within west Grand Bay were either reduced to half their former dimensions
or had disappeared entirely. Similarly, the elongate, northwest-northeast oriented marsh
island situated on the east side of Point aux Chenes Bay was reduced to half its 1921 width.
Reworked by wave action, the seaward shore of South Rigolets Island was transformed from
its highly irregular 1921 coastline to a nearly straight shoreline with a southwest-northeast
orientation. The irregular, east-west oriented north shore of Point aux Chenes Bay was
transformed into a nearly straight coastline. Crescent-shaped, flood-tidal deltas (dotted
lines), located between the adjacent islands south of Point aux Chenes Bay, indicate an up-
bay transport of sediment. During this period, four tropical storms struck the area in the
years 1922, 1923, 1934, and 1939, while hurricanes hit in 1926 and 1932. The 1932
hurricane made landfall between Pascagoula, Mississippi and Mobile, Alabama.
Between 1940 (Figure 34) and 1952 (Figure 35), erosive forces bisected the elongate
northwest-southeast oriented island on the east side of Point aux Chenes Bay. By 1952, the
14
seaward islands, remnants of Grand Batture Island, were reduced to approximately two-
thirds their 1940 lengths. The islets northeast of South Rigolets Island disappeared. The
seaward shore of South Rigolets Island along with all of the Grand Batture Islands migrated
northwest. The flood tidal deltas in the passages between the islands south of Point aux
Chenes Bay grew as the passages increased in width. On the northeast side of South
Rigolets Island, the length of the embayment, from seaward entrance to head, had increased.
In addition, the northwest-southeast oriented marsh island north of South Rigolets Island was
bisected. Two tropical storms made landfall in the vicinity during the 1940-1952 period.
The first storm occurred in 1944. The second storm made landfall at Biloxi, Mississippi in
1947.
Assessment of land mass changes over the relatively short period, 1952-1957, were
based on an aerial photograph of 1952 (Figure 35) and a navigation chart issued in 1957
(Figure 36). Among the noticeable changes that took place was the narrowing of the
peninsula that extends southeast of the seaward boundary of the south shore of Middle Bay.
Other changes were the narrowing of the northeast end of South Rigolets Island, the
recurving of the west end of South Rigolets Island, and the apparent disappearance of the
two flood tidal deltas between South Rigolets Island and the islets south of Point aux Chenes
Bay. Much of the marshy mainland shore in northwest Grand Bay eroded away, leaving a
highly irregular shoreline and many new marsh islands. Two tropical storms occurred in
1955 that may have contributed to these changes. The center of the first storm made landfall
at Bay St. Louis and the second passed through New Orleans.
The impact of erosion during the 18-year period from 1957-1975 is obvious from
comparisons made between the 1957 chart (Figure 36) and an aerial photograph of October,
1975 (Figure 37). Islets present in the northern part of Point aux Chenes Bay in 1957 were
greatly reduced in size and the linear north shore of 1957 became very irregular with many
small embayments. The two northwest-southeast oriented marsh islands north of the west
15
tip of South Rigolets Island were heavily eroded. The west end of South Rigolets Island was
cut off, forming a separate island. The island northeast of South Rigolets Island, a remnant
of Grand Batture Island, was reduced to roughly one-half of its 1957 dimensions. The
northeast tip of South Rigolets Island vanished during the interim. During this time period,
two tropical storms occurred, one striking Pensacola, Florida, and one hitting Pascagoula,
Mississippi. There were also several hurricanes that contributed to the area's erosion. The
hurricane that struck the Louisiana coast in 1965, while causing only minimal damage to
buildings and homes, was responsible for appreciable erosion of Mississippi's barrier islands
and mainland coast. Camille, the most powerful hurricane to strike the North American
continent in recorded history, struck the Mississippi Coast in 1969 with devastating results.
Although, the area is not shown in Figure 37, the islands that had lain southwest of South
Rigolets in 1957, i.e. the remnants of the western portion of the former Grand Batture Island,
were reduced to shoals by the force of this hurricane (author's personal observations). The
hurricane surge height in the study area was approximately 10 feet above mean sea level.
Because of the questionable accuracy of land areas depicted on the navigation chart
produced in 1978, it is difficult to ascertain exactly what changes occurred during the 1975-
1978 period. Silhouette charts produced from a 1975 aerial photograph (Figure 37) and the
navigation chart printed in 1978 (Figure 38) show few appreciable changes during this 3-
year period. The island that formed as the result of the bisection of the west tip of South
Rigolets Island sometime during 1957-1975 had since reconnected. Because of the length
of time required for revising navigation charts, errors that appear in this 1978 chart are
probably due to the cartographers' use of data that was no longer valid by the time the chart
was printed. After 1978 only aerial photographs or remote-sensing imagery were used to
produce the silhouette charts. The first of two notable errors that appear on the 1978 chart
is the existence of the northward oriented point on the northeast tip of South Rigolets Island
which, according to the 1975 aerial photograph, was shown to no longer exist. A second
16
significant error in the 1978 chart is the existence of some islands and the greater size of
others which, according to the 1975 aerial photograph, had either already disappeared or had
been reduced to a size much smaller than they appear on the 1978 chart. No tropical storms
or hurricanes made landfall near the area during the 1975-1978 period.
Conclusions drawn from comparisons made between the images produced from the
1978 navigation chart (Figure 38) and from an aerial photograph taken November 15, 1979
(Figure 39), support the previous determinations regarding the actual configuration of the
land in 1978. Figure 39 shows that no islands existed southwest of South Rigolets Island by
November 15, 1979. They most likely disappeared before October 1975, although we have
no evidence to substantiate this. There is strong coherence between the configuration of the
west end of South Rigolets Island as depicted in the charts for 1975 and 1979, neither of
which are in agreement with the shape depicted for that area in the 1978 navigation chart.
The evidence leads us to rely less on the shape and dimensions of land masses depicted on
the 1978 chart than we might have otherwise. Shoals, the submerged remnants of the former
Grand Batture Island, are visible in the 1979 aerial photograph.
The degree of erosion that occurred in less than five months, i.e. November 15, 1979
to April 9, 1980 (Figures 39 and 40), is clearly indicated by the diminished size of the
islands, islets, and peninsulas. In addition, the leeward and seaward shores of South Rigolets
Island and the north shore of Point aux Chenes Bay reflect the impact of erosion. Many of
the embayments and passages have increased in size. Hurricane Bob, which made landfall
near Grand Isle, Louisiana, caused a rise in sea level of about 3.5 feet at Point aux Chenes
and waves of appreciable size. However, most of the erosion can be attributed to the fury
of Hurricane Frederic that made land fall at Dauphin Island, Alabama, and Mobile, Alabama,
on September 14, 1979. Sustained winds of 115 knots and peak winds of 126 knots were
recorded as the hurricane made landfall. Frederic was the most intense hurricane of this
century to affect the Mobile, Alabama - Pascagoula, Mississippi area. The hurricane surge,
17
recorded at Dauphin Island at a height of 11 feet, washed over the island carrying with it
much sediment which it deposited as overwash fans on the island's north shore. Therefore,
even though the height of the surge at Point aux Chenes was less, it was still a significant
erosive force.
The changes due to erosion from 1980 to 1986 (Figures 40 and 41), a period of
approximately six years, were not great. Erosion of the shorelines around the north,
northeast, and east perimeter of Point aux Chenes Bay was manifested in the disappearance
of islets and the reworking of the seaward shore of South Rigolets Island. Although it lies
outside of the study area, it is worthwhile to note the degree of erosion that has taken place
east of Heron Bayou. On September 2, 1985, The center of Hurricane Elena moved onshore
at Biloxi, Mississippi. Maximum coastal winds of 91 knots with gusts to 117 knots were
recorded at Dauphin Island, Alabama.
During the period 1986 to 1988 (Figures 41 and 42), a period of approximately 30
months, erosion took a heavy toll on Point aux Chenes. Comparison of the size and
configuration of South Rigolets Island at the beginning and end of this period shows that the
island was reduced to two-thirds its 1986 size. The shoreline perimeter of Point aux Chenes
Bay from north around to the southeast was eroded extensively during this relatively short
time period. Similarly, the land masses contiguous to Middle Bay and west Grand Bay show
that substantial erosion had occurred. Florence, a minimal hurricane that made land fall over
southeast Louisiana on September 9, 1988, caused a rise in sea level of about 4 feet and
generated substantial waves at Point aux Chenes.
Changes in the location of the shoreline relative to a transect perpendicular to the
local shoreline were measured on the silhouette charts at several select points at Point aux
Chenes for the period 1940-1988. Based on this series of measurements, the average annual
land loss due to coastal erosion has been approximately 17 acres per year. This is higher
than what others have estimated the rate to be.
18
The percent grain-size composition and relevant statistics for the sediment samples
are included in Table I. Location of the sample sites are shown in Figure 29. At site 7, four
samples, 7a, 7b, 7c, and 7d, were taken inside the west end of South Rigolets Island and from
the submerged bar located southwest of the island. On the mainland side of the island,
sample 7a is from offshore, 7b is at the shoreline, and 7c is from the lower beach face.
Sample 7d is from the submerged bar offshore to the southwest. At site 8, a sample was
taken just offshore (8a) and another (8b) from the lower beach face.
The digital brightness values of the Thematic Mapper Simulator near-infrared band
(.76-.90 :m) were processed using an arctangent function via ATLAS/AGIS software (Delta
Data Systems, Picayune, Mississippi). To construct a pseudo-color image of the coastal
surfaces at Point aux Chenes from the processed, contrast-stretched brightness values, the
color palette and image manipulation algorithms of the FIGMENT software system (Dr.
Richard Miller) were used. The color scale key beside the images on Figures 43 and 44
represents the 256 processed brightness intervals of the near-infrared band, from the lowest
(bottom) to the highest (top).
While these unsupervised images provide some important information to those
familiar with the area, those unfamiliar with the area could be seriously misled by the
patterns. The lack of "groundtruthing" due to contract constraints forced the authors to rely
upon the systems unsupervised classification algorithms which has resulted in some areas
being classed the same even though the "surfaces" are quite different. The red color in the
lower parts of the figures represent the higher areas of the salt marsh while the dark green
represents the water-covered interior of the salt marsh. The yellow and light tan areas
represent the open savannas and flat, grassy areas of sparse pine forests. The "reds" and
"greens" in the lower parts of the false-color image show good correlation with the
distribution of the saline marsh vegetation described in previous studies (Criss 1990, Criss
and Eleuterius 1992, Eleuterius and Criss 1992).
19
Because of the 25 meter ground resolution of the TMS, there is a problem with
interpretation of these images that should be mentioned. The spectral signature obtained for
each 25 meter by 25 meter square of ground area is the aggregate of the spectral radiances
reflected from all of the "surfaces" within the square. Because of the possible spanning of
dissimilar "surfaces", e.g. a bayou and adjacent salt marsh, the resulting classification may
be neither bayou nor marsh, but something quite different.
Observed during one aerial survey were a series of offshore bars which paralleled the
south coast of South Rigolets Island, but which extended well beyond it in both directions.
20
Discussion
Comparative analyses of charts and aerial photographs indicate that coastal erosion
at Point aux Chenes has been and continues to be substantial. During the period when the
Escatawpa River discharged into Mississippi Sound at Point aux Chenes-Grand Bay, erosion
was limited to that caused by relatively weak tidal and wind-driven currents and waves
which were generated within the confines of Mississippi Sound. The Escatawpa River Delta
was situated in rather quiescent waters, sheltered from the Gulf of Mexico hydrodynamics
by the long barrier island, Dauphin. The amount of sediment eroded was more than offset
by the seaward transport and deposition of sediment by the Escatawpa River. With the
change in the course of the river, the supply of sediment it had provided to the coast ceased.
The former relationship between the amount of sediment deposited and that lost to erosion
was dramatically altered. Erosion became dominant, but was a relatively slow process when
compared to the rate of erosion observed today. When a hurricane cut through Dauphin
Island in 1740 creating a new island (Petit Bois) with a wide passage (Petit Bois Pass)
between them a new era of erosion began. The new passage allowed the larger waves
generated in the Gulf of Mexico to enter Mississippi Sound and attack the shores at Point
aux Chenes. Tidal currents also became stronger because the new passage allowed the
admittance of more tidal energy. The rate of erosion accelerated.
Tidal currents with speeds reaching 1 knot have been calculated for and observed in
the shallow coastal waters. Currents with speeds of this magnitude can efficiently transport
most sediments found in the area.
Wind waves and swells of dimensions sufficient to erode and transport sediments
occur year-round. However, it is normally during winter when strong northerly winds and
during late summer when strong southeasterly winds generate and drive larger than average
waves that the preponderance of erosion occurs. In general, the southerly-directed waves
21
of winter attack the shores exposed to the north and the northerly-directed waves of summer
attack the shores exposed to the south.
From 1848-1988, thirty-eight tropical storms and hurricanes have either made
landfall at Point aux Chenes or have passed in such close proximity as to cause erosion.
Large waves and surges accompanying hurricanes and tropical storms were responsible for
dramatic changes in the area.
Based on the changes in land masses as determined from charts and aerial
photographs for the period 1848-1988, the estimated rate of erosion is approximately 17
acres per year. There was, however, considerable variation in the annual rates of erosion
determined for each time period ascribed by the charts and photographs. This can be
explained largely by the non-uniform occurrence of tropical storms and hurricanes. The
variability in the rate of erosion between sites along the coast within a given time period is
most likely related to the differences in the degree of exposure to the direct attack of waves.
The orientation of the series of offshore bars that parallel the south shoreline of South
Rigolets Island indicates that the predominant wave direction is toward 310° during late
summer, one of the two most erosive periods of the year. Further study of these offshore
bars may provide information regarding the wave period and length of the most erosive
waves. Accurate information regarding wave dimensions and period are essential to the
construction of wave-refraction diagrams for the area. These diagrams will be needed for
judicious planning in the event a barrier to replace the former Grand Batture Island is to be
constructed.
Knowledge gained from monitoring coastal erosion at Point aux Chenes for several
years combined with that which has accrued from this study has enabled the authors to
develop two scenarios of coastal erosion for Point aux Chenes. The scenarios involve two
factors, water level and prevailing waves, which are of primary importance in the erosion
22
of the marshy shorelines. Other important factors contributing to the accelerated erosion are
the composition and engineering properties of the sediments.
The first scenario applies when the water elevation is low on the tidal plane, i.e. when
the still-water level is near the base of the scarp of the marsh substrate. Waves traveling
shoreward upon "feeling" bottom peak and break against the marsh substrate. Sustained for
a period of time, this process results in undermining the overlying marsh. When the
concavity reaches the depth where the weight of the overlying marsh and substrate can no
longer be supported, the substrate falls away in large clumps. Surging breakers have a
similar effect when the still-water level is near the base of the marsh substrate scarp.
The second scenario applies when the water elevation is high on the tidal plane, i.e.
near the top of the marsh substrate. These higher water elevations may be due to either
spring tides or strong winds directed toward the coast. In this case, waves directed
shoreward "feel" bottom abruptly as they approach the scarp and plunge forward, breaking
on top of the marsh substrate. If the scarp has been previously undermined by erosion, the
undermined portion may be broken away in large clumps under the impact of the breaking
waves. There is an effect of this scenario that should be discussed.
Sediment laden waters directed inland after impacting the marsh substrate may
literally cut away the marsh vegetation, leaving only stubble for 10-15 feet inland, beyond
which a fan of sediment is laid down. In some instances, the first few inches of the marsh
substrate may also be removed in the process. Narrow, irregular channels from 2-10 feet
long may be cut into the marsh by the attack of waves under the conditions described in this
scenario.
The accelerated erosion occurring along the marshy shores at Point aux Chenes is
due, in part, to the nature of the marsh substrate. Because the substrate consists of
unconsolidated sediments rich in decaying plant material and containing a large amount of
interstitial water, it is easily eroded. The numerous burrows of fiddler crabs and voids left
23
by decaying roots and other organic deposits weaken the substrate further, making it even
more prone to erosion.
The fate of sediments eroded from Point aux Chenes is only partly identified by the
sediment distribution chart (Figure 3). The large clumps of marsh substrate that break away
as described in the two erosion scenarios are rapidly broken down by wave action.
Winnowing and sorting by wave action separates the sediments into various components.
The fate of the sediments depends upon the length of time the sediments remain in
suspension relative to the period of the prevailing waves. If the length of time the sediment
remains in suspension is less than the period of the wave, the sediment remains near shore.
If, on the other hand, the length of time the sediment remains in suspension is greater than
the wave period then the sediment is removed from the area, perhaps to be deposited at some
great distance from the point of erosion.
The coarse sands generally remain in the area, likely moving offshore and onshore
with the seasonal changes in the wave climate. This material may accumulate to form
narrow strips of sand beach near the base of the marsh scarp. The finer sands may be carried
along shore by longshore and tidal currents or offshore by tidal and density driven currents.
Both coarse and fine sands are found within the embayments, carried there by flood-tide
currents or by waves entering the bays. The fine silts and clays which remain in suspension
longer may be carried farther into the bays before they are deposited, but more likely the
greater portion is carried seaward by ebb tidal currents.
Discerning the trend and rates of coastal erosion at Point aux Chenes permits rather
crude forecasting of the future of Point aux Chenes with regard to erosion. The northwest
retreat of the area's south and southeast margins due to erosion is one notable trend.
Occurring simultaneously with the retreating coastline has been the fragmentation and
overall reduction in the size of the marshy islands. With the breach of the protective barrier,
i.e. Grand Batture Island, and later its total destruction, the largely marsh areas behind it
24
have borne the brunt of the direct attack by waves and storm surges. The composition and
porosity of the marsh substrate makes the sediments particularly vulnerable to erosion.
Based on the information synthesized here, the future of Point aux Chenes is rather grim.
By 2042, over 850 acres will have vanished. The shoreline configuration will be drastically
changed from that at present. The seaward margin of the peninsula of marsh that now
terminates with the south shore of South Rigolets Island will likely be located at the present
north shore of North Rigolets. The marshy shorelines in all areas will have retreated from
their present positions. Accompanying this loss of wetlands will be losses in marine
"fishes", mammals, reptiles, herptiles, and birds, including migratory waterfowl. The
economic and social value of the area will suffer greatly.
25
Recommendations
Based on our study, we make the following recommendations:
1. Acquire the area referred to here as Point aux Chenes and designate it a wildlife
refuge.
2. Locate and identify all of the rare and endangered plants that now inhabit the
marshes and uplands at Point aux Chenes.
3. Continue efforts to construct a barrier where Grand Batture Island was located,
however, be certain that the seaward side of the barrier is oriented 40°-220°
to help stabilize the shoreline.
4. Establish a series of paired reference markers along the shores of Point aux
Chenes. These reference points, if monitored frequently, will provide a more
accurate determination of the rate of erosion than it is possible to ascertain
by other methods.
5. Initiate a program to educate the public, particularly residents of Jackson County,
regarding the value of Point aux Chenes.
Acknowledgements
We would like to express our appreciation to Mr. Joe Gill, Deputy Director, and Mr.
Larry Lewis, Chief, Coastal Management, Mississippi Department of Wildlife, Fisheries,
and Parks, Coastal Division/Bureau of Marine Resources for their support. We are indebted
to Dr. Thomas McIlwain, Director, Gulf Coast Research Laboratory, who, having recognized
the importance of the work, committed the Laboratory to providing the preponderance of
support needed. Mr. Malcolm Ware and Mr. Gene Brown, librarians at the Gunter Library,
made special efforts to secure certain essential materials. To them we owe a debt of
gratitude. We thank Dr. Ervin Otvos for his analyses of sediment samples. To Mr. Hank
Svelak and other members of the United States Geological Survey located at Stennis Space
26
Center, who were both generous with their time and equipment, we are also indebted. The
originals of three silhouette charts in this report were prepared by Mr. Joe Jewell when he
was a technician in the Physical Oceanography Section at Gulf Coast Research Laboratory.
27
Table I. Composition and characterization of sediment samples fromPoint aux Chenes (Sites identified in Figure 29).
________________________________________________________________________
Sample Components in Percentages CharacterizationSite samples Sand Silt Clay================================================================
1 -- 81.2 12.1 6.7 Muddy-fine sand
2 -- 79.6 10.4 10.0 Muddy very-fine sand
3 Small shell 72.0 21.2 6.8 Coarse silty very- fragments fine sand
4 Plant material 33.7 49.7 16.6 Very-fine sandy coarse silt
5 Plant material & 50.7 37.4 11.9 Coarse silty very- shell fragments fine sand
6 Plant material & 33.9 31.7 34.4 Very-fine sandy mudshell fragments
7a Molluscan 75.1 22.5 2.4 Coarse silty very- fragments fine sand
7b Molluscan & plant 83.2 14.3 2.5 Coarse silty very- fragments fine sand
7c Molluscan & plant 99.1 (0.9 mud) Fine sand fragments
7d Oyster shell 32.3 48.9 18.8 Very-fine sandy fragments medium silt
8a Plant material & 32.4 49.2 18.4 Very-fine sandyshell fragments coarse silt
8b - 99.2 (0.8 mud) Fine sand
9 Plant material 28.5 61.8 9.7 Very-fine sandycoarse silt
46
Literature Cited
Christmas, J. Y. and Richard Waller. 1973. Phase IV: Estuarine Vertebrates, Mississippi.Pages 320-406 in: J. Y. Christmas (editor). Cooperative Gulf of Mexico EstuarineInventory and Study, Mississippi. Gulf Coast Research Laboratory, Ocean Springs,Mississippi.
Christmas, J. Y. and Walter Langley. 1973. Phase IV: Estuarine Invertebrates, Mississippi.Pages 255-319 in: J. Y. Christmas (editor). Cooperative Gulf of Mexico EstuarineInventory and Study, Mississippi. Gulf Coast Research Laboratory, Ocean Springs,Mississippi.
Coastal Mississippi Wetlands Initiative Team. 1989. Coastal Mississippi WetlandsInitiative, Gulf Coast Joint Venture: North American Waterfowl Management Plan.Unpublished Report.
Criss, G. Alan. 1990. Evaluation of airborne Thematic Mapper Simulator (TMS) DigitalData and High Altitude Aircraft Infrared Photographs for Assessment of Conditionsin the Vicinity of Pt. aux Chenes Bay, Mississippi. Presented at the Fifty-fourthAnnual Meeting of the Mississippi Academy of Sciences, Biloxi, Mississippi, 22-23February 1990. Journal of the Mississippi Academy of Sciences 35(Supplement):73-74.
Criss, G. Alan and Charles K. Eleuterius. 1992. Delineation of Spectrally-Complex CoastalWetland Habitats Via a Combination of Data from the Daedalus Thematic MapperSimulator and Aerial Photographs. Presented at the Fifty-sixth Annual Meeting ofthe Mississippi Academy of Sciences, Biloxi, Mississippi, 13-14 February 1992.Journal of the Mississippi Academy of Sciences 37(1): 48.
Eleuterius, Charles K. 1974. Mississippi Superport Study: Environmental Assessment.Office of the Governor, State of Mississippi. 153 pages.
Eleuterius, Charles K. 1979. Hydrology of Mississippi Sound North of Petit Bois Pass.Mississippi Marine Resources Council. 57 pages.
Eleuterius, Charles K. and Sheree L. Beaugez. 1979. Mississippi Sound: A Hydrographicand Climatic Atlas. Mississippi-Alabama Sea Grant Consortium, Ocean Springs,Mississippi. MASGP-79-009. 145 pages.
Eleuterius, Charles K. 1984. Estimated Maximum Tidal Currents for Selected Passes inMississippi Coastal Waters. In: A Contingency Guide to the Protection ofMississippi Coastal Environments from Spilled Oil: Protection Priorities andRelated Environmental Information. Mississippi Department of WildlifeConservation, Bureau of Marine Resources, Long Beach, Mississippi. 48 pages.
47
Eleuterius, Lionel. 1971. Submerged Plant Distribution in Mississippi Sound and AdjacentWaters. Journal of the Mississippi Academy of Sciences 17: 9-14.
Eleuterius, Lionel. 1973. Phase IV: The Marshes of Mississippi. Pages 147-190 in: J. Y.Christmas (editor). Cooperative Gulf of Mexico Estuarine Inventory and Study,Mississippi. Gulf Coast Research Laboratory, Ocean Springs, Mississippi.
Eleuterius, Lionel. 1973. Phase IV: The Distribution of Certain Submerged Plants InMississippi and Adjacent Waters. Pages 191-197 in: J. Y. Christmas (editor).Cooperative Gulf of Mexico Estuarine Inventory and Study, Mississippi. Gulf CoastResearch Laboratory, Ocean Springs, Mississippi.
Gazzier, C. A., R. L. Frederking, and V. H. Minshew. 1980. Mapping Coastal Wetlands ofMississippi with Remote Sensing. Pages 187-198 in: F. Shahrokhi (editor). RemoteSensing of Earth Resources Vol. III. The University of Tennessee Space Institute,Tullahoma, Tennessee.
Meyer-Arendt, Klaus J. and Karen A. Kramer. 1991. Deterioration and Restoration of theGrand Batture Islands, Mississippi. Mississippi Geology 11(4).
Minshew, V. H., Conrad A. Gazzier, Lynn P. Malbrough, and Thomas H. Waller. 1975.Environmental Geological Analysis: Jackson County, Mississippi. MississippiMineral Resources Institute, University of Mississippi.
National Ocean Service. 1991. Tide Tables 1991: High and Low Water Predictions. EastCoast of North and South America including Greenland. U.S. Department ofCommerce, National Oceanic and Atmospheric Administration.
Otvos, Ervin G. 1979. Barrier Island Evolution and History of Migration, North-CentralGulf Coast. In: Stephen Leatherman (editor). Barrier Islands. Academic Press.
Otvos, Ervin G. 1981. Barrier island formation. Marine Geology 43: 238-243.
Perry, Harriet and J. Y. Christmas. 1973. Phase IV: Estuarine Zooplankton, Mississippi.Pages 198-254 in: J. Y. Christmas (editor). Cooperative Gulf of Mexico EstuarineInventory and Study, Mississippi. Gulf Coast Research Laboratory, Ocean Springs,Mississippi.
Priddy, R. R., R. M. Crisler, C. P. Sebren, J. D. Powell, and Hugh Burford. 1955.Sediments of Mississippi Sound and Inshore Waters. Mississippi Geological SurveyBulletin, No. 82.
Rees, Susan Ivester. 1991. Environmental Studies. In: General Design Memorandum,Main Report: Improvement of the Federal Deep-Draft Navigation Channel;Pascagoula Harbor, Mississippi. U.S. Army Corps of Engineers, Mobile District.December 1990, Revised July 1991.
Waller, Thomas H. and Lynn P. Malbrough. 1976. Temporal Changes in the OffshoreIslands of Mississippi. Water Resource Research Institute, Mississippi StateUniversity.
CoverTitle PageTable of ContentsList of TablesTable I. Composition and characterization of sediment samples from Point aux Chenes
List of FiguresFigure 1. Study AreaFigure 2. Marsh associated with Point aux Chenes BayFigure 3. Centralized map of bottom sediments in the study areaFigure 4. Wind speed (knots) and direction, JanuaryFigure 5. Wind speed (knots) and direction, FebruaryFigure 6. Wind speed (knots) and direction, MarchFigure 7. Wind speed (knots) and direction, AprilFigure 8. Wind speed (knots) and direction, MayFigure 9. Wind speed (knots) and direction, JuneFigure 10. Wind speed (knots) and direction, JulyFigure 11. Wind speed (knots) and direction, AugustFigure 12. Wind speed (knots) and direction, SeptemberFigure 13. Wind speed (knots) and direction, OctoberFigure 14. Wind speed (knots) and direction, NovemberFigure 15. Wind speed (knots) and direction, DecemberFigure 16. Predicted Tidal Ranges for 1991, Pascagoula, MississippiFigure 17. Wave height distributions, JanuaryFigure 18. Wave height distributions, FebruaryFigure 19. Wave height distributions, MarchFigure 20. Wave height distributions, AprilFigure 21. Wave height distributions, MayFigure 22. Wave height distributions, JuneFigure 23. Wave height distributions, JulyFigure 24. Wave height distributions, AugustFigure 25. Wave height distributions, SeptemberFigure 26. Wave height distributions, OctoberFigure 27. Wave height distributions, NovemberFigure 28. Wave height distributions, DecemberFigure 29. Sediment sampling locationsFigure 30. From chart circa 1848Figure 31. From chart circa 1860Figure 32. From U.S. C. & G.S. Coast Chart No. 189, 1896Figure 33. From chart circa 1921Figure 34. From aerial photograph of October 27, 1940Figure 35. From aerial photograph of April 30, 1952Figure 36. From chart circa 1957Figure 37. From aerial photograph of October 20, 1975Figure 38. From chart circa 1978Figure 39. From aerial photograph of November 15, 1979Figure 40. From aerial photograph of April 9, 1980Figure 41. From aerial photograph of April 23, 1986Figure 42. From aerial photograph of November 21, 1988Figure 43. TMS pseudo-color image of Point aux Chenes, November 21, 1988Figure 44. TMS pseudo-color image of West Point aux Chenes-Bangs Lake, November 21, 1988
IntroductionBackgroundMethodologyResultsDiscussionRecommendationsAcknowledgementsLiterature Cited