Hiroaki SATO

Numerical Simulation about Flushing of the River-Mouth Bar of Aganogawa-River

Tokuzo HOSOYAMADA

Generally river-mouth bar cause decrease in the capacity of flood discharge and itfs dangerous in a flood. When a flood of massive discharge, the river-mouth bar is undermined largely and itfs called Flushing. Expansion of river width and increase of capacity of flood discharge are needed from point of view of flood control. However flushing which is important keyword of flood control happen largely and momentarily. Observation is difficult and its mechanism has not been solved.
At aganogawa-river which is focused on this study, it has been considered by many floods until now that discharge of 5,000m3 can flush. When the flood by typhoon No.6 at 14 Heisei, river-mouth bar was undermined. However itfs not enough to call flushing. Then water level was loft up and in places it was over the danger level of river. In this way it can be declared that estuary of aganogawa-river is safety. And if itfs not safety, control of river-mouth bar should be considered.
Therefore in order to understand flushing more clearly and in order to consider about influence of flushing, 2-D numerical simulations were done with cannel topography of aganogawa-river in this study.