Two mathematical models by using a MIKE21 flow model with a physical model are both established to simulate the flow field of the confluence near Sanligeng reach. Because of good correspondence of simulating results and test data in comparison with each other,the establishment of the two models are both proved to be successful. Hydraulic research results given by the mathematical model show that shear force,impact force and circulation flow in the deep pool are the largest along the groove. The sediment whi...