Numerical simulations for flood flows in a symmetrical river confluence were performed using a quasi-three dimensional numerical model. The vertically averaged and moment equations was used as governing equations to allow for the incorporation of pre-assumed linear distribution of horizontal velocity and quadratic vertical velocity and pressure distributions. The model is based on finite volume method using HLL (Harten, Lax and van Leer(1983)) numerical flux, which is one of a Riemann solver. The model is verified against two experimental data of flows in curved channel and in symmetrical river confluence. It shows that the model can reproduce the complex behavior of the flows with reasonable accuracy.
