Dynamic modeling of hydrologic and soil erosion processes in catchment needs appropriate simulation methods to handle the water and sediment transfer on hillslope and in channel

as well as the initial and boundary conditions.Soil erosion in watershed

as a spatially and temporally coupled process

is divided into soil erosion in channels and soil erosion on hillslope.Soil erosion in watershed is partitioned into a surface-line system to deal with the hillslope-channel relation and a line-line connection for soil erosion in channel.The governing differential equation with initial and boundary conditions was outlined for watershed erosion modeling.The comparison of laboratory experimental results with model outputs indicates that the simulation accuracy is above 80%

which demonstrates the feasibility of the method.The simulation method presented in this study may supply a basis and reference for the simulation of soil erosion in watershed.