Modeling Inlet Sand Bypassing

Abstract

Consideration of the magnitude and phasing of sand bypassing events with respect to incident wave conditions is necessary when modeling shoreline change adjacent to tidal inlets where sand bypassing occurs. Likewise, the effects of wave transformation over nearshore bathymetric features (i.e., ebb tidal shoals, bypassing bars, etc.) and the resulting variations in alongshore sand transport rates relative to bypass discharge locations should also be considered. This paper presents a method for developing time-dependent inlet sand bypassing data for use in predicting future shoreline change. The method includes developing a relationship between the local offshore wave climate, longshore sand transport regime and inlet sand bypassing utilizing coincident time series of (1) local wave climate and (2) sand bypassing. The proposed model is compared to two other typical sand bypassing models to demonstrate the importance of relating the wave climate and bypassing. The proposed method was used successfully to create a representative time series of both mechanical and natural sand bypassing data for a shoreline change study conducted for the downdrift shoreline of South Lake Worth Inlet, Florida.