Grid width is generally treated as the width of flow path for flow convergence in many traditional distributed hydrologic models.The flow velocity obtained from these models differs substantially from the reality

which may undermine immensely the accuracy of the results in hydrologic modeling

soil erosion simulation and other related studies.A distributed hydrologic model was developed based on Horton infiltration curve and simplified Saint Venant equation in this study.A curve called as flow path width curve was developed to describe the varying of flow path width with upstream contributing area as flow gathering.Some observed data of Dongwan watershed was applied to test the model

and the results proved its superiority in distributed outputs.