Investigation of the River Bed Changes using HEC-RAS4.0 Model Case Study: Talar River

Information on erosion and capacity of sediment carrying condition in various basins is one of the subjects that in each of hydrology and river engineering projects should be considered. In the present study HEC-RAS model was applied to evaluate and predict the sedimentation and erosion in the reach of Talar River with 12 km length. For doing this study 40 cross section which was surveyed in 2006 is applied in the simulation and 4 cross section which was surveyed in 2011 applied for calibration of the model. Model calibration and verification showed that the Meyer Peter Muller sediment transport equation has a better fit with the observed results. In order to predict the erosion and sedimentation trend, using recorded data of dischrges in Shirgah hydrometric station during last 30 years and using SAMS Statistical model, the amounts of monthly stream flow was predicted for the next 10 years and then sedimentation model was executed. Variations in the longitudinal profile of river in all profiles showed that the most changes will occurs within the middle reach area and the beginning of the river reach with the length of about 1000m and with having the mild slope is stable. Also predicted amount of sediment outflow from the studied reach is about 348534 tones for the next 10 years.