587 



to reduce our activities of this nature, it is probable that pressures of 

 population and economics will force continuing estuarine construction. 

 As construction takes place within coastal areas, many changes will 

 occur in the estuaries. The effects of these changes should be known 

 before constructing industrial plants, homes, highways, or airports; 

 dredging canals or draining marshes. This sort of information is espe- 

 cially essential if a meaningful permit review system is to be instituted 

 and maintained. Physical alterations of estuarine and coastal zones by 

 dredging, filling, bulkhead construction, ditching for mosquito con- 

 trol, and construction of new marsh requires investigative work that 

 would determine the effects on water quality, the effects on biological 

 life, and the effects on hydraulics. Special attention should be paid in 

 the development of new hai^bors to retain or enhance the structural 

 components necessary for those organisms requiring protected waters 

 for their reproductive activities. 



PHYSICAL AND MATHEMATICAL MODELING 



Estuarine systems will continue to receive heavy utilization for all 

 types of man's activities. Population trends indicate that coastal areas 

 are attracting a disproportionate percentage of our expanding popu- 

 lations. With this trend we also have the industrial activities necessary 

 to support the economy. At the present time, we cannot predict accu- 

 rately the assimilative capacity of estuarine systems, nor can we pre- 

 dict the degree of degradation that will result from the engineering 

 projects proposed as necessary to provide the supporting services for 

 the social and industrial structure. 



The solution to these problems might well be approached by simula- 

 tion techniques. It is urged that efforts be intensified to provide physi- 

 cal and mathematical models of estuarine systems which are being 

 subjected to population and industrial pressures. Experience indicates 

 that when such models are available they are used extensively by Fed- 

 eral, State, and industrial interests to provide guidance for the proper 

 management of estuarine resources. 



Two systems of simulation or modeling are normally considered: 

 the physical model and the mathematical model. Probably the true 

 utility of the physical model has not yet been established. The devel- 

 opment of such a model for an important estuary has a great deal of 

 appeal for teaching, demonstration, and to some extent for control 

 purposes in addition to the predictive capaibility rendered. There is no 

 question that advantages of such a model are clear for teaching and 

 demonstration. What is not as clear is the extent to which such physi- 

 cal models may be employed to predict and solve problems of pollu- 

 tion, sedimentation, physical modification, and structures in the 

 estuary. 



The use of mathematical models to simulate the dynamic phenome- 

 non of the estuary has only recently been subjected to rigorous exam- 

 ination. Research in this area should be encouraged. A complete 

 appraisal of the relative merits of physical and mathematical models 

 should be made. The advantages and disadvantages of each type of 

 model for different purpose studies should be fully delineated. 



Finally, to complete the objective of optimally maintaining or 

 enhancing estuarine water quality, management models need to be 



