Streambank Sensitivity of Haji arab River to Erosion and It's risks

Human and natural factors cause the river to be out of equilibrium and this imbalance leads to changes in erosion and sedimentation. One of the forms of erosion in rivers is stream bank erosion which can change the plan and morphometry of the river and due to these changes, various hazards including : Change the morphometry of the channel and produce sediment may happen. Changing in river's pattern, longitudinal and transvers displacement of the river, occurrence of bank accretion, changing hydrological and geometric characteristics can be the results of change in river's sedimentation and erosion. Monitoring the variables affecting the stability of bank and stream characteristics can be effective in preserving human life and property also managing the natural environment. In this research the method of Rapid Geomorphic Assessment (RGA) has been used for investigate the stability and morphometric change in Haji Arab river that located in south of Qazvin province. For this purpose were chosen 8 reaches. Field studies and mapping were done from all reaches. The parameters of Oklahoma Ozark Streambank Erosion Potential Index (OSEPI) were scored during the field studies. In this research have been used statistical analyzes. Results show that the unstable stream banks belong to reaches of 1 in left side (down strem) and 7(up stream) in right side also the stable reaches are the reaches of 2(down stream) in left side and reach of 3 in right side. the most effective factor in stability of Haji Arab river's bank in both sides is riparian woody vegetation after that in left side stream curvature and in the right side Stream Curvature, Percentage of Bank Height with a Bank Angle Greater than 80 o, Unconsolidated Material equally are the most effective factor in stability.