VI-65 



HYDROLOGY AND MORPHOLOGY 



In order to use a resource effectively, management first must quantify 

 how much of the resource there is to use. In the case of estuaries-- 

 which, like all water resources, are primarily self-renewing when used 

 proper ly--the quantity of water, the areas of marsh and associated lands, 

 and the types of modifications which have been made constitute the 

 total resource which is presently available. Most of this information 

 exists, either in available literature or in widely scattered files. 



The data required include "Fills", a tiny word, yet it represents the 

 only final and irretrievable damage that can be inflicted on a body 

 of water. Information on circulation-modifying structures of other 

 types— dredged channels, bridges, causeways, small upstream impound- 

 ments, etc. --are also needed. 



It is imperative that records be kept of such construction and that 

 their effects on a system be carefully monitored. These records and 

 monitoring data must be studied minutely in order to learn the most 

 effective and least damaging methods to use when estuarine modifica- 

 tion is necessary. 



Considered separately these small structures--dikes, weirs, locks, 

 etc. — appear innocuous, yet even one on a stream tributary to an 

 estuary can have profound effects on salinity levels and current 

 patterns. Changes in these, in turn, can upset the ecological balance 

 of an area far out of proportion to tne size of tne regulation 



