erosional conditions. Exponential decay proved to be valid for onshore 

 transport as well, but the spatial decay coefficient was almost constant, with 

 an average value of 0.11 m'^. 



545. For Zone II, which extends over the narrow range from the break 

 point to the plunge point, it was difficult to extract information on the 

 transport characteristics from the LWT experiments. However, an exponential 

 decay with distance offshore showed good agreement with transport rate data 

 inferred from the small number of available cases, with a spatial decay 

 coefficient about 0.20 of the value of the spatial decay coefficient appli- 

 cable to Zone I. Zone III encompasses the main part of the surf zone, and the 

 transport rate was demonstrated to be closely related to the energy dissipa- 

 tion per unit volume, based on the CRIEPI experiment results involving wave 

 height distributions and profile change. Values of empirical coefficients in 

 the transport equation found through regression analysis were similar to 

 values found by other authors through more indirect numerical modeling. 



546. In Zone IV, the region dominated by runup and backrush, the 

 transport rate is governed by swash dynamics. A transport rate expressed in 

 terms of physical quantities could not be developed for this zone due to lack 

 of measurements of swash wave properties. However, the transport rate showed 

 an approximately linear behavior for both offshore and onshore transport for a 

 wide range of conditions. The extent of Zone IV decreased if the profile 

 eroded and a step evolved, and the transport rate simultaneously decreased 

 with time. 



547. A numerical model of profile response was developed on the basis 

 of quantitative analysis of the LWT wave and profile change data. The domain 

 of model extends from the depth of significant net cross -shore sediment 

 movement, located seaward of the largest breaking waves, to the limit of runup 

 on the beach face. The model calculates the wave height distribution across - 

 shore at each time-step with linear wave theory up to the break point, and 

 thereafter with a breaker decay model in the surf zone. The break point is 

 determined from an empirical criterion, derived from the CRIEPI data set, 

 relating the breaker ratio to the surf similarity parameter defined by the 

 deepwater wave steepness and the local slope seaward of the break point. A 

 nonlinear shoaling theory was applied initially but found to overestimate the 



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