Hydraulic Simulation the Improving Methods Using the Mathematical Model Hec-Ras4 (Case Study: Karun River)

The operation dredging of river bed and also creating a cut off for removing sharp meander and maintain proper alignment is effective non-structural methods for decreasing the flood level. This study compared the effects of 1) Dredging karoon river at ahvaz range, 2) Removing heterogeneity height in order to make uniformly downstream slope, 3) Removing ahvaz downstream horseshoe Meander, which has been analyzed by HecRas4 model. Data modeling analysis showed that dredging in the form of bed dig in ahvaz range will not have significant effect on water level profile. This method only increase sedimentation and erosion rate in ahvaz range. Achieving to better results, the idea of dredging ahvaz downstream between two meander in order to regulate hydraulic gradient through removing heterogeneity height was proposed. Findings showed that this method has significant effect on improving of Hydraulic of flow and dredging effectiveness. Finally, it will be found that removing of the ahvaz downstream horseshoe meander is the most effective method for reducing level of flood and sedimentation rate in ahvaz range.