Performance of a Sand Trap Structure and Effects of Impounded Sediments, Channel Islands Harbor, California.

摘要

Monitoring of one complete filling cycle of a sand trap located at Channel Islands Harbor, California, has yielded textural and bathymetric data that (1) document patterns of infilling and sediment texture of the trapped sand, (2) compare coring versus surface grab sampling for describing native beach and fill sediment textures, and (3) determine the textural properties of trapped sediments and evaluate their performance as beach fill. This study was conducted at the conclusion of the Coastal Engineering Research Center's (CERC) long-term field investigation relating longshore transport volumes to wave energy thrust measurements. The data collected for this study consist of 28 vibratory cores of sediments, 8 cores from sites along a native beach profile, and 20 cores from sites within the trap. The long-term sediment transport study provided the remaining data used in this report. In general, the trap functioned as designed, trapping the bulk of longshore transport which entered the trap mouth in a series of pulses or surges of sand. From an analysis of the textural data it is concluded that sediment distribution within the trap area is similar to that of the updrift coastline although the trapped sand is slightly finer and better sorted than the native beach sand. Also from the textural distributions within the trap, it is concluded that the sediment as beach fill but that bypassing could be planned to utilize the textural patterns in the construction of a beach fill downcoast.