FIGURES 



Number Page 



Frontispiece. Salt marshes along the Mississippi deltaic coast characterized iMcinp 

 by extensive tidal channels COVER 



1 The groves of trees in the middle of this broad expanse of marsh 



identify the site of old Indian villages 2 



2 The oil storage facility for the nations' s only superport is 

 constructed in a salt dome in the middle of a Mississippi delta 

 brackish marsh. The maze of pipes is the primary aboveground 

 expression. An old oilfield also sits atop this submerged salt dome 



as shown by the network of tree-lined oilwell access canals 3 



3 Across this expanse of marsh and swamp looms the Mew Orleans skyline 

 through the haze, a reminder of the proximity of heavy industries and 

 concentrated popul ations 4 



4 Louisiana oil and gas production 5 



5 Map of the Mississippi River Deltaic Plain showing the hydrologic 



units 7 



6 The seasonal variation of insolation at various latitudes. The 

 computation assumes a transmission coefficient of 0.7 throughout 9 



7 Mean monthly air temperature at New Orleans, Louisiana 10 



8 Generalized water budget for the Mississippi delta marshes 10 



9 Average water budget for the upper Barataria basin, 1914-1978. 

 P=precipitation, PE=potential evapotranspiration, AE=actual 



evapotranspi ration 11 



10 Freshwater inflows to the Mississippi Delta. Discharges are in cumecs. 

 All discharges are for water year 1978 except Mississippi River, which 

 is a long-term mean representing the combined average annual 

 discharge above the confluence of the lower Mississippi (10400 cumecs) 



and the Atchafalaya (5000 cumecs) Rivers 12 



11 Water level trends in delta marshes:, a) long term; b) seasonal; 



c) daily 13 



12 Tide levels at Shell Beach, in the Pontchartrain-Lake Borgne basin, 



associ ated wi th ni ne major storms 14 



vii 



