cross -shore distribution of longshore sand transport which can be integrated 

 to obtain the total longshore transport rate. 



Problem Statement 



13. Estimation of longshore sand transport rates is essential for the 

 design of coastal and riverine structures and construction and maintenance of 

 navigable waterways. Design of structures penetrating the surf zone, such as 

 groins and jetties, and the resultant erosional or depositional features they 

 are expected to produce requires estimation of the cross -shore distribution of 

 longshore transport. Low-crested structures such as reef breakwaters and weir 

 jetty sections can be optimally designed with information about relative 

 magnitudes of bed load and suspended load or, ideally, a prediction of the 

 vertical distribution of transport. 



14. The streamer trap shows much promise for use in the nearshore, yet 

 the hydraulic and sand- trapping properties of the streamer trap were not 

 investigated by its developer (Katori 1982, 1983). Therefore, in the present 

 study, extensive laboratory investigations augmented by limited field inves- 

 tigations were conducted to determine these properties. Two unidirectional 

 flow experiments were performed in the laboratory to replicate the longshore 

 current occurring in the field. The first experiment determined the hydraulic 

 characteristics of 23 streamer trap nozzles and identified several nozzles 

 with near-optimum hydraulic efficiencies. The second experiment, qualita- 

 tively and quantitatively, evaluated the sand -trapping efficiency of those 

 nozzles determined to have near-optimum hydraulic efficiencies. Character- 

 istics of the H-S sampler were also investigated for comparison with results 

 previously reported in the literature. 



Report Organization 



15. Uses of the streamer trap are described in Part II. Part III 

 presents results of the hydraulic tests. Part IV discusses hydrodynamic 

 elements of the coastal zone and unidirectional flow regime and presents 

 results of the sand- trapping efficiency tests. Field experiment results are 



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