234 



Research Needs 



Simple models can definitely be useful for sensitivity studies of 

 various scenarios, including different sea level stands, recharge rates, 

 and pumping rates. 



Knowledge of model reliability is needed, particularly when the 

 subsurface geologic structure and boundary conditions are poorly defined. 



Better evaluation of climatic effects is needed, so that various 

 scenarios (including status of river supply of fresh water) can be testedj 

 in models. 



Models to demonstrate water availability should be combined with 

 econometric models, to evaluate societal responses to changes in water 

 availability and costs. Optimization modeling should be demonstrated for 

 effectiveness in combining all water sources for minimum cost. 



Barrier technologies -- injection, extraction, and geotechnical -- can 

 be explored for improved methods and materials. 



Alternative water sources should be explored, particularly inter- 

 basin diversion and desalinization, if econometric models show that huge 

 price increases in water may be required to deal with shortages. 



SECT. 10. SEDIMENTATION PROCESSES IN ESTUARIES 

 Text Discussion 



Atchafalaya Bay delta growth results, as mentioned in the text, are 

 highly dependent on apparent sea level rise . Recent results with more 

 carefully developed, spatially variable rates confirm the effect. The 

 effect extends to flood protection designs, which are markedly different 

 with and without projected rise. 



Plant die -off in marshes and marginal areas, caused in part by 

 saltwater intrusion, will dramatically affect erosion and deposition of 

 shorelines . 



Sediment supply rates are changing, which is another primary reason 

 for Louisiana land loss. This effect could be exaggerated by climate 

 changes or by different water resource policies caused by sea level rise 

 and rainfall changes . 



Redistribution of sediments and generation of new sediment sources and 

 sinks will occur, altering dredging requirements by changing shoal 



