河口デルタの拡大・縮小に起因する海浜変形(1)一寺泊・野積海岸での河口デルタの形成一

Abstract

Large scale coastal behavior due to river mouth delta change is one of the most typical beach changes in Japan.As a site of river mouth formation, Teradomari-Nozimi coast was investigated in this paper.Shoreline change simulation is carried out in terms of the one-line model which is modified to be applicable to the river delta formation process by considering the effect of sediment which move down into an area deeper than the depth of sediment initiation.First, the original beach topography (before formation of delta) is reproduced by using both Dean's equilibrium beach profile and the initial shoreline position.The unknown parameter of Dean's beach profile (A) is estimated by core sample of boring in which an obvious difference in sediment diameter distributions between before and after formation of delta is observed.Secondly, the hindcast of the shoreline change is performed after specifying the incident wave condition with observed wave data for six years, and estimating the sediment input from the channel with depth sounding data.Then the computational conditions and assumptions are calibrated by comparing computed and measured shorelines.Finally 100-year prediction of the shoreline change is carried out for the future plan of development in this coast.