during higher energy conditions. "High-energy" conditions which occurred during 

 the study period were waves of above-average height and wind-driven currents o£ 

 above-average speed in the nearshore zone. High-speed longshore currents were 

 associated with the occurrence of both conditions. A summary of the study re- 

 sults is included to provide a coherent basis for interpretation. 



2. Shore-Normal Transport . 



Profile analysis showed that the disposal bar form migrated shoreward. 

 Associated with this trend was a shoreward shift in the location of maximum 

 sediment accretion in the offshore subzones. This landward shift, as well as 

 prolonged accretion in the landwardmost subzone, indicates onshore nourishment 

 by the more seaward subzones. The disposal sediment, coarser than that of the 

 native offshore sand, moved obliquely onshore as documented by textural study. 

 Thus, net movement of the disposal sediment for the shore-normal component was 

 landward, in the direction of the naturally occurring coarser beach and surf 

 zone sand. 



Landward -oriented asymmetric ripples developed in the disposal sediment. 

 Active asymmetric ripples usually migrate in the direction of the steep face. 

 Thus, this bed-form type may serve as additional, indirect evidence for shore- 

 ward movement of sediment comprising the bed form. 



As the disposal bar moved shoreward and the total offshore volume decreased, 

 the inshore zone and beach showed overall accretion. At the same time, the 

 natural surf zone bar was displaced landward or eroded, and the trough filled. 

 Coarse sediment similar in appearance to the disposed sediment had spread through- 

 out the inner bar trough region. The disposal bar caused waves to break seaward 

 of the surf zone bar, especially at low tide, effectively causing the surf zone 

 bar to be located in a mid-surf (bore-dominated) region. Presumably, bore action 

 tended to eliminate the bar form and move material into the trough. 



Although particles of disposal sediment mixed with the native beach sand, 



net accretion on the beach was slight. The beach ridge, which began to develop 



before disposal and eventually welded onto the backshore throughout the study 

 period, was related to a natural cycle of beach change (Hayes, 1977). 



There was no evidence for seaward displacement of the disposal bar. Follow- 

 ing the major storm on 16 September, the beach, inshore, and offshore zones did, 

 however, undergo temporary erosion. Although some of this loss is presumed to 

 have been seaward, evidence indicates a major amount of longshore transport (see 

 Section V,4) . 



3. Shore-Parallel Transport . 



The inshore zone northeast and southwest of the disposal sector experienced 

 a high rate of trough filling. Longshore currents were observed to move much of 

 the sediment along the entire inshore zone. Several times the coarse sediment 

 filling the inshore zone of the sector was traced in the direction of the long- 

 shore current, and beyond the limits of the study area. 



It is difficult to assess the amount of shore-parallel movement of disposal 

 sediment out of the offshore disposal area into adjacent offshore areas. Place- 

 ment of a sediment pile in the nearshore should create a local disequilibrium, 



36 



