Prediction of Overall Beach Changes on Shizuoka and Shimizu Coasts Using a Morphodynamic (BG) Model
Abstract:
Background: On the Shizuoka and Shimizu coasts located along the western shore of Suruga Bay in Japan, a wide sandy beach had formed owing to the abundant fluvial sand supplied by the Abe River. However, extensive river bed mining was carried out before the 1970s, resulting in a decrease in sand supply from the river. This caused a significant reduction in longshore sand transport and severe erosion downcoast. As a measure against beach erosion, a large number of detached breakwaters, as well as five artificial headlands, have been constructed along the coastline. Then, after the prohibition of riverbed mining in the 1980s, a large amount of sand was resupplied from the river and such sand was transported alongshore while forming a sand body owing to the existence of de tached breakwaters. These movements of the sand body along these coasts were investigated, and measured beach changes were reproduced using the BG model (a model for predicting 3-D beach changes based on Bagnold’s concept). By this calculation, we were able to reproduce the overall beach changes of the coast associated with the movement of a sand body, and the effect of beach nourishment was evaluated.
