A Continuous Simulation of Runoff in a Small Watershed of the Loess Plateau with a Distributed Model

摘要

A physically based distributed hydrological model (THIHMS-SW, Tsinghua Integrated Hydrological Model System-for Small Watershed) is developed to adapt to the special conditions of the Loess Plateau, in which topsoil is discretized into several layers with different thickness in the numerical calculation of soil moisture movement in saturated-unsaturated zone. The result of continuous simulation of runoff in Chabagou small watershed for 8 years from 1960 to 1967 indicates that the simulated peak discharges and runoff depths match well with the observed ones at the scale of sub-watershed and whole watershed in relatively nature state, and Nash coefficients are all higher than 0.70, although more attention should be paid for some specific floods and smaller sub-watershed to obtain better simulation results.