location (used as backup data to determine whether the analysis 

 techniques are yielding the desired results). Note that the 

 measurement system recommended includes the measuring of tidal 

 heights. Since the sensors do not filter, all filtering is 

 accomplished analytically during the data analysis. 



The measurement of sediment transport, onshore-offshore and along- 

 shore, is probably the most difficult problem in obtaining adequate 

 prototype data required for model verification. Although the accuracy 

 of sediment transport measurements (or the most practical way to make 

 them), is difficult to determine, a carefully planned measurement program 

 is considered to result in sufficient accuracy for model verification. 

 Some type of tracer measurement will probably yield the best data; how- 

 ever, the program must be more extensive than any conducted to date. 

 Profiling of the beach and offshore area beyond the breaker zone is re- 

 quired at as close an interval as possible (once a day is desirable). 

 The planning of a detailed sediment transport measurement program is 

 difficult, and the best method is not as obvious as in the case of wave 

 measurements. However, rapid advances are being made in the area of 

 oceanographic and estuarine surveying and mapping. 



b. Selection of Model Scales and Materials . As discussed previously, 

 the complete similitude of all dynamic processes involved in the movement 

 of coastal sediment is impractical. The modeling of cohesive bottom sedi- 

 ments is not discussed in this section because it is considered beyond the 

 present state-of-the-art. Modeling of the motion of noncohesive sediments 

 (sands and cobbles) presents a formidable task in itself. As shown pre- 

 viously, similitude of certain dynamic processes fixes the relation be- 

 tween model and prototype linear dimensions, material characteristics, 

 and other factors. Therefore, no particular set of scale-model laws for 

 coastal sediment models is recommended at the present time. Each of the 

 scale-model laws in Table 5-1 is believed to have its own special area of 

 application, and the selection of the appropriate set of equations (model 

 laws) for a particular problem largely depends on the experience and ex- 

 pertise gained by a particular group of laboratory personnel in perform- 

 ing movable-bed scale-model tests. 



In arriving at a set of scale-model laws to be applied for a given 

 problem at a specific location, the following items must be analyzed: 



(1) Existing prototype wave environment.. This includes 

 monthly wave statistics (niimerical wave hindcasts are prefer- 

 able) , the incidence of severe storms on the west coast of the 

 United States and the Great Lakes, and the incidence of hurri- 

 canes on the east and gulf coasts of the United States. 



(2) Computation of the prototype longshore transport (possi- 

 bly using several different approaches). 



(3) Size of the prototype area to be studied. 



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