Bank Erosion Potential and Channel Instability in Haji Arab River Located in Buin Zahra, Qazvin

Water flow is one of the earth processes that in addition to changing earth surface, affect human's life. Any change in channel properties affects other variables specially where human intervention disturbs the balance of the environment it can lead to hazards. Stream Bank erosion is very vital and important because stream bank erosion can result in loss of land, increased stream sediment load, diminishing water quality and aquatic habitat, threatens people's lives and property. Identifying and determining stable and unstable banks also determining their degree of stability can be a great way to manage fluvial 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 8 reaches were chosen. Field studies and mapping from all reaches were done. Based on channel stability index (CSI) that is one of the Rapid Geomorphic Assessment's (RGA) indicators. The parameters of this index (CSI) were scored during the field. In this research statistical analyzes such as correlation coefficient and Box & Plot diagram were used to determine the relationship between the parameters in the stream banks and data scatter. also relative score was used to determine the most effective factor in stability of stream banks, Results show that the highly unstable stream banks belong to reaches of 7, 8 and the most effective factor in the Haji arab river's bank ,based on Channel Stability Index(CSI) are stream bank erosion and riparian woody vegetation .