Complex three-dimensional flows around river confluences are characterized by the secondary flow as well as primary flow, and it also causes intense local scouring and deposition. So, numerical simulation models which include effects of three-dimensional flows are required to calculate flows around a river confluence.In this study, first, we evaluate reproducibility of several functional forms describing vertical velocity distributions of flows around a river confluence by using measured data by Rhoads et al.(1995). Second, we develop a bottom velocity computation method with water surface velocity equation using the general coordinate system. And then, the validity of the model is discussed through the comparison with the measured results.
