FIGURES 



Number Page 



1-1 The Chenier Plain coastal ecosystem of Louisiana and Texas 3 



1-2 An illustration of the Chenier Plain ecosystem liierarchy 4 



1-3 The interaction of major ecological and physical processes in the Chenier Plain ecosystem 5 



1-4 Graphic symbols used in ecological modehng 6 



1-5 A diagrammatic systems model of an aquatic habitat 7 



1-6 Contents of the Chenier Plain Ecological Characterization Study 8 



2-1 The six basins of the Chenier Plain ecosystem 11 



2-2a Physiography of the western Chenier Plain showing chenier ridges (in black), 



from photomosaics and published maps 12 



2-2b Physiography of the eastern Chenier Plain showing chenier ridges (in black), 



from photomosaics and published maps 13 



2-3 Bolivar Peninsula and the adjacent coast with cross sections of sediment facies 



across beaches. Borings were made during the summer of 1955 by Mclntire, 



Saucier, and Gagliano 14 



2-4 Major trends in global climate during the past 10,000 years 16 



2-5 GeneraMzed hydrologic cycle of the Chenier Plain 17 



2-6 Bivariate frequency distribution of wind speed and wind direction offshore of 



Sabine Pass by season. Percentages of occurrence are given in the margin 18 



2-7 Seasonal fluctuations in solar radiation, air temperature, precipitation, and rain 



surplus at Lake Charles, from National Weather Service records 18 



2-8 Volume of water pumped from different sand strata in the Lake Charies area from 1935-65 22 



2-9 Depth to the water table in the Gulf Coast Aquifer at Houston, Texas, 1939-72 23 



3-1 Generalized model of major ecological processes of the Chenier Plain basins 26 



3-2a Annual production (millions of barrels) of gas and oil in Louisiana 1965-72, and 1977 31 



3-2b Annual value (millions of dollars) of oil and gas in Louisiana, 1960-75 31 



3-3 Numbered geopressure/geothermal prospect locations in southern Louisiana 31 



3-4 Area and number of farms in each basin of the Chenier Plain 34 



3-5 Change in area of harvested cropland and yield of rice in coastal Louisiana 36 



3-6 Water usage for agriculture in Louisiana in 1967 38 



3-7 Volume of water used for agriculture in each basin 38 



3-8 Percentage distribution of monthly water usage in southwestern Louisiana in 1967 38 



3-9 Annual muskrat and nutria pelt production for coastal Louisiana 1968-76 39 



3-10 Estimated number of muskrat pelts produced from the Chenier Plain basins, based on 



1975 habitat areas and on harvest densities determined by Palmisano (1972a) 39 



3-1 1 Estimated number of nutria pelts produced from the Chenier Plain basins, based on 



1975 habitat areas and harvest densities determined by Palmisano (1972 b) 39 



3-12 Income and percentage contributions from the various trades, industries and services 



for each of the basins in the Chenier Plain 54 



3-13a Major pipeline routes in the western Chenier Plain 56 



3- 13b Major pipeline routes in the eastern Chenier Plain 57 



3-14 Total waterborne commerce in the Chenier Plain 1967 to 1976 59 



3-15 Hydrologic regions and habitats of a Chenier Plain basin 63 



3-16 Average surface salinity (°/oo) contours along the Louisiana coast during (A) high river 



stage, April 21-29, 1963 and (B) low river stage, December 11-16, 1963 64 



3-17 Tidal phases at several locations along the Louisiana and east Texas coasts 65 



3-18 Monthly water-level fluctuations for 1963-66, and montlily mean and standard deviation, 



1963-74, in the Calcasieu Basin 66 



3-19 The relationship of mean river discharge to watershed area for three Chenier Plain basins 67 



3-20 Mean monthly rain surplus or deficit estimated from rainfall, temperature, and 



evapotranspiration for the Upper Calcasieu River drainage basin, and the 



surface water flow into the Calcasieu River at Kinder, Louisiana 67 



3-2 1 Relationship between water levels and different weather types for Calcasieu Lake 



near Hackberry, Louisiana; text describes synoptic weather types 70 



3-22 The hours per month that the water levels are above mean liigh water in marshes 



at Hackberry, Louisiana 71 



3-23 The relationship of the trophic state index of water to drainage density in the upper 



part of Barataria Basin, Louisiana. The regression line accounts for 59% of the 



variation among points and is higlily significant statistically 74 



3-24 Realtionship between canal density and wetland loss rates (A) in coastal Louisiana, 



and (B) in the Barataria Basin, Louisiana 80 



3-25 The ratio of marsh edge length to total wetland area, by marsh type, in each basin 82 



ix 



