APPLICATION OF THE POROSITY-BED VARIATION MODEL CONSIDERING THE SHELTERING EFFECT OF IMMOBILE SEDIMENT TO THE FIELD EXPERIMENT ON SEDIMENT SUPPLY

Abstract

 Selective supply of fine sediments to a gravel-bed river that contains varying grain sizes leads to riverbed fluctuations. This is due to filling of the fine sediments between gravels and the sheltering effect on the flow of immobile materials. When implementing sediment replenishment from dams to the downstream river, it is important to evaluate the impact on bed variations including biological habitats. A model representing such sediment transport is essential for this purpose. This study presents an extended bed variation model that considers the sheltering effect of exposed riverbed materials and changes in porosity to represent riverbed variations with fluctuations in the exchange layer. The model was applied to a sediment supply field experiment conducted in the Yahagi River to confirm its practicality.