Analysis and estimation of the risk of erosion by using the BSTEM model in the Kawtar River Basin

The rivers have been known from the past to this day as the most populous areas of the planet. The expansion of urbanization and the increase of human needs have created a balance between rivers and disruptions in the river system. One of the most important river hazards is the erosion of the river bank. It causes many economic, social and environmental damages every year. The present research is based on fieldwork and modeling of erosion of the river Bank. Therefore, it seeks to identify sensitive areas of the Bank erosion and estimate the extent of erosion. For this purpose, the NBS index and BSTEM model has been used to identify and estimate the erosion of the Kwtar River in Mahabad. A route of 3 km was selected from the Kwtar River. Morphological characteristics of five cross sections for NBS index and three intervals for BSTEM model were taken. Rosgen’s proposed seven parameters for assessing the near bank stress (NBS) index. In this research, three parameters were used for the estimation of bank erosion. Two parameters and the highest efficiency in the identification of river bank erosion was cauterized. While the parameter was somewhat contradictory to reality. Then using the BSTEM model, simulation of normal and flood flow and its consequences on the Toe Erosion and Bank Stability were studied. The BSTEM model evaluates the stability of the edges with the safety factor (FS). The main cause of the erosion of the Toe is due to hydraulic currents and the main cause of instability and fracture failure due to the geotechnical characteristics and the underlying hydraulic flow along the sides Toe Bank of the Kawtar River. As the rate increased, the amount of foot erosion and the fracture failure rate were increased.