QUASI-THREE DIMENSIONAL FLOOD RUNOFF MODEL ON SURFACE AND SUBSURFACE FLOWS

Abstract

A simplified model for subsurface flow computation is developed by splitting thecontinuity equation on the flow into vertical and horizontal directions based onthe evaluation that the major part of the lateral flow occurs in the saturated zone. This model is combined with the surface flow model on the channel network and applied to the Abukuma River watershed of 5, 400km² area to reproduce the flood in 1998. Discharge hydrograph computed by this model shows good agreement withthe observed one and remarkable improvement from the surface flow model.