Abstract: The transverse water surface slope and secondary flow are main hydraulic features of bend flows,which are the result of the interaction bewteen the gravity and the centrifugal force in bend flows.The hydrodynamic characteristics of bend flows such as the water surface slope,the longitudinal velocity,the transverse circulation,the turbulence kinetic energy and the in tensity of secondary flow vary with the water depth in downstream.A series of flume experiments were conducted in a U-shape bend to study these hydrodynamic characteristics.Results show that the water surface slope,the longitudinal velocity,the turbulence kinetic energy and the intensity of secondary flow generally decrease with the increase of downstream water depths.The decline appears to be uneven in diferent sections of thebend.The results are favorable to further study on the effect of backwater to the structure of bend flows.