導流堤を含む浜名湖今切口周辺地形と漂砂移動特性

Abstract

This paper explores the characteristics of sediment transport around Imagire-guchi, the opening of Hamana-Lake. Special focus was put on the spatial distributions of tidal current velocity, which should be the primary force that causes sediment transport and resulting local sedimentation characteristics in the lake. We first performed field survey and obtained the distribution of tidal current velocity across Imagire-guchi as well as suspended sediment concentration. The measured current velocity had significant variation across the tidal flow direction and, in the eastside of the opening, time-varying velocity profile was asymmetry, i. e., the landward high-tide current velocity was larger than the ebb-tide seaward current velocity. Similar asymmetric feature was observed in the measured suspended sediment concentration. As a result, we deduced that certain amount of sand may still flow into the lake in the east-side of the opening while vice versa in the other west-side of the opening. Finally, we performed numerical analysis that surely explained the observed feature and somehow supported our deduction.