Takaaki YASUTA
Numerical study for changes of Agano river-mouth bars by coastal waves and river flow
Tokuzou HOSOYAMADA
In Agano river, which has its river mouth in Japan sea, there are river-mouth bars affected by seasonal weather changes such as winds, waves and river discharge. The river-mouth bars develops and vanishes according to the seasonal weather changes. In general, river-mouth bars decrease cross-section area of river and harm river discharge. Risk of flood disaster hazard increases finally. From the river management of view, it is important to understand basic mechanism of formation of river sand bars subject to coastal waves and river flows.
In this study, I examined bathymetrical changes caused river flow and waves by numerical model. Multi-directional irregular waves are used for incident wave condition for the purpose of consistency of natural condition.Terrain model convert DEM(Digital Elevation Model) data from Agano river mouth bathymetric image.Numerical results shows that deformation of sand bars are strongly affected by river flow discharge and incident wave directional conditions The shape of sandbars simulated by the model agree well with airborne image of the Agano river-mouth.
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