VI-56 



The great amount of effort now being expended in the development of 

 estuarine mathematical models and the attempts to apply systems analysis 

 techniques in the estuarine zone are seriously hampered by the lack of 

 fundamental information on the physical oceanography of estuaries. 

 The data needs pertinent to this Section are for actual measurements 

 of tidal, current, and stratification ohenomena. 



The obtaining of physical oceanographic information requires both a 

 program of consistent routine data collection over a large geographic 

 range and intensive case studies in individual systems. 



SEDIMENTS AND SEDIMENTATION 



All water, even the tiniest trickle, picks up and bears along minute 

 particles from its bed. These particles may be invisible to the eye, but 

 they are there and they are carried along suspended until, at some place 

 where the current slows and gravity gets the upper hand, they fall to 

 the bottom of the v;ater course. These particles are ^'sediments" and 

 the way in which they settle out is "sedimentation." 



In some areas of the estuarine zone, natural sediment transport and 

 sedimentation cause drastic changes. However, natural sedimentation 

 is generally a long-term process to which the ecosystem can adaot-- 

 that is, if a given species cannot tolerate a natural characteristic 

 of a given environment, the species would not exist in that environment 



