Beach Erosion and Recovery

Abstract

Our capability for predicting beach and dune erosion has improved in the last three decades, but the recovery of an eroded beach above the mean sea level (MSL) cannot be predicted at present. The cycle of beach erosion and recovery will need to be predicted for the long-term maintenance of a sand beach with a dune for coastal flooding reduction. The cross-shore numerical model (CSHORE) is extended and evaluated using natural beach erosion and recovery data along 16 cross-shore lines spanning 5 km alongshore for the duration of 272 days. The CSHORE predicts beach and dune erosion fairly well, as has been shown in previous comparisons. The bed-load formula used in the CSHORE is adjusted to predict the accreted beach profile with a berm. The computed beach profile evolutions are shown to be affected little by the alongshore gradient of the longshore sediment transport rate along the straight beach. The extended CSHORE predicts both erosion and accretion above MSL within a factor of about 2.