Identification of prime factors of active river bank erosion in the lower course of Ganga Bhagirathi River: a study

The present study aims to identify prime factors of active and continuous riverbank erosion. Field visits were conducted from 2015 to 2019. To fulfil the objective of the study, 21 study units prone to bank erosion were selected along the banks of Ganga-Bhagirathi at Jangipur sub-division. Remote sensing and geographic information system were used to measure the area under erosion and deposition from the 1985 to 2015 at five-year intervals. Bank height, bank angle, length of fracture from bank line, river velocity, and channel depth were measured for each study unit using different instruments like cup-type water current meter, clinometers, and measuring tape. Soil samples were collected for textural analysis. Factor analysis was performed to find out prime responsible factors for active riverbank erosion. The result of the study shows that bank height, bank angle, channel width, and fracture length together comprise the first component, which explains 29.48 percent of variance. Riverbank erosion happens due to physical and manmade factors in the lower plain area of the Ganga-Bhagirathi River.