ABSTRACT
After rainfall intensity exceeds soil infiltration, water accumulates on the surface and the flows down the slope under gravity as overland flow. This rainfall-runoff process considered soil erosion or transportation of sediment had been simulated by numerical models which had been developed since 1960s. However, flows of water and sediment very over a large range of sediment concentration. The term hyperconcentrated flow is most often applied between water floods and debris flows, and could exist in both high and low discharges.
