Two Dimensional Simulation of Flow pattern and Bed Changes in Straight and Meandering Channels under the Effect of Spur Dike

Spur dikes as one of the main structures in river restoration practices are used for protecting and shaping the river banks and main channels. These structures growing from the river natural banks, having suitable length and angle relative to the flow direction and cause deviation of the flow from the riversides and driving it to the central axis of the river. In this study, the numerical hydrodynamic and sediment transport model “CCHE2D” was used to simulate the flow pattern and streambed changes around the spur dikes. Two separate series of experimental data were used to assess the numerical model outputs. The accuracy of the model outputs were evaluated through common statistical parameters including RMSE, MARE, REmax and R2. Comparison of the experimental results with the simulated values revealed that the CCHE2D was reasonably capable to simulate the flow pattern around the both of single and series of spur dikes with high accuracy (correlation coefficient=0.755-0.955). The bed changes around the series of spur dikes were simulated with acceptable accuracy, revealed that the CCHE2D model could precisely predict the maximum scouring depth with correlation coefficient of 0.990, but overestimated the width of scour hole around the spur dike in comparison with experimental observations. Furthermore, both the numerical results and experimental observations showed that the erosion depth of main channel had a direct relation with the length of spur dike.