深海波候および底質粒径を用いた沿岸漂砂量の推定

A simple formula is derived to estimate the longshore sediment transport rate. The derivation is based on modification of procedures developed by Coastal Engineering Research Center (CERC). Several aspects of the CERC's original formula are elaborated and modified. The proposed formula is based on the assumption that the appropriate beach slope in the surf zone is the ratio of the breaker depth to the surf zone width. Consequently, the formula is expressed as a function of sediment grain size and deep water wave climate to account for the dependence of the beach slope on deep water wave climate. An attractive aspect of the proposed formula is that it does not require bathymetric data and can therefore be easily applied at places where detailed bathymetric data are lacking. The proposed formula agrees reasonably well with CERC's approximate formula which uses deep water wave data as input. However, the proposed formula has an advantage over the CERC's approximate formula in the sense that it considers the effects of the beach slope and the width of the surf zone on the longshore sediment transport rate. These are important transport parameters which are not considered in the CERC's approximate formula.<BR>To investigate the applicability of the formula, net monthly transport rates along the Hyuga Nada Coast, Miyazaki, Japan, are estimated. Estimated results show that northward rates are predominant and these can be interpreted from aerial photograph and satellite imageries.