Abstract: An unsteady flow model is established for numerical simulation of flow between Tingzikou and Shaxi Dam in the middle reach of the Jialingjiang River.Finite difference method based on Preissmann 4-point implicit scheme is employed in the study.Roughness coefficients are rated by using the measured water surface data of the river reach during flood,and the medium and low stages in the year of 2001.The model with corresponding numerical methods are verified by the field water surface profile data of Silong to ...