Simulation of lateral velocity distribution in rivers using Finite Elements Method (Case study: Berentine hydrometric station in Minab River)

Lateral profile of flow velocity in rivers is the base of stage-discharge rating curve development and also flow and sediment transport calculations. Regarding to high difficulties in measurement of lateral distribution of velocity in natural rivers, especially in time of floods, using the suitable numerical methods is essential. On the other hand, by entering the flood flow into floodplains, flow interaction induced at the main channel-floodplains interface and causes high complexity in flow hydrodynamics. In this research, using finite element method, velocity lateral profiles have been predicted by solving quasi 2-D differential equations of flow in compound channels. Proposed model is based on the depth-averaged Navier-Stocks equation. For evaluation of accuracy, this model has been calibrated and then validated in Minab River at Berentine hydrometric station, in Hormozegan province, based on measured data obtained during 3 flood events. Comparison of measured and predicted profiles of lateral velocity in two phases of calibration and validation shows acceptable accuracy of the proposed mathematical model. Statistical analysis of numerical results shows that the determination coefficients for calibration and validation phases are 0.97 and 0.96, respectively. Also, the root mean square error of these phases are 0.13 and 0.23, respectively. Finally the stage-discharge curve of this river has been predicted with good accuracy.