NUMERICAL SIMULATION OF BED-POROCITY VARIATION APPLYING TO ACTUAL RIVER

Abstract

Downstream of cross river structure, such as dams, it is often investigated that the grain size distribution becomes coarsened because of interruption of sediment transportation. If fine sands supplied to the coarsened bed, the porosity is decreased and the bed material becomes finer without bed deformation. Furthermore, the change of void structure of river bed is very important issue for habitats.

It is necessary to evaluate the river bed deformation with change of porosity and its influence on habitats. However, the practical method to evaluate the process is not established.

In this study, bed-porosity variation model easily to apply to the actual river is constructed. Then this model is applied to numerical channel on actual river scale, and it is confirmed that the model is able to simulate the bed deformation and porosity change with selective sediment supply, such as supply only fine sand from dam.