IV-6 



can not only tolerate the dynamic balance of conditions but actually 

 depend on the constantly recurring environmental variations to sustain 

 themselves. 



The wide range of interaction of the two basic driving forces of 

 gravity and solar energy brings about a bewildering variety of 

 individual environments in the estuarine zone, each being dominated 

 and controlled by a different combination of factors. Some may be 

 dominated by tidal range, some by river flow, some by geometry of 

 the coastline, some by climate, some by the sediments deposited, 

 and some by combinations of these. The variety is infinite. 



Yet, within this variety, there is order which lends itself to 

 measurement and through measurement to management of the estuarine 

 zone to preserve it for continuing multiple use. The purpose of 

 this discussion is not to present a detailed analysis of the 

 differences among the parts of the estuarine zone, but rather to 

 outline what these differences are, why they exist, and what must 

 be measured to establish a basis for sound technical management 

 within the overall framework of wise institutional management. 



It would be convenient if the state of knowledge were such that the 

 estuarine environment and its variety could be described in terms of 

 the primary forces which control it; then it would be possible to 

 manage each estuarine system efficiently and exactly for optimum use. 



