Two-Dimensional Modeling of Rainfall Runoff and Sediment Transport in Small Catchment Areas

A mathematical model of rainfall runoff formation in small catchments is developed; the model is physically valid. The model gives an adequate description of such processes as interception of rainfall by vegetation; storage in relief micro-depressions; infiltration; overland runoff; wash off, transport and re-deposition of soil particles. Numerical simulation of formation of the surface runoff involves the solution of two-dimensional nonstationary shallow water equations, the infiltration equation, and the sediment transport equation. The shallow water equations and the sediment transport equation are integrated numerically using conservative implicit first-order finite-difference schemes. The finite-difference scheme for the shallow water equations allows simulating an open flow with a free boundary. Verification of the model is based on observed data for rain-induced high water in catchment areas of the Butenya river.