Field based inventory of river bank erosion susceptibility model (BESI) of Raidak-II river in the Himalayan foreland basin

Abstract

ABSTRACT River bank erosion is a fluvio-hydrological hazard, and sometimes, it turns into disaster in the human-encroached river bank and flood plain. The principal objective of this study is to detect the river bank erosion potential zone using new Bank Erosion Susceptibility Index (BESI) model and spatiotemporal shifting of river Raidak-II (1980–2020). Sedimentary bank facies (SBF) analysis was conducted to identify the nature of cohesiveness of bank materials. The result showed that the maximum average lateral shifting (213.20 m) was recorded in the year 1990 (right bank), whereas the minimum average shifting (77.32 m) was measured in the year 2020 (right bank). The result also showed that the right bank of Raidak-II was mostly oscillated due to poorly sorted quaternary non-cohesive bank materials. The Bank Erosion Hazard Index (BEHI) model showed that 46.15% and 50% bank erosion sites are fallen in high-to-extreme bank erosion susceptibility zones in the years 2020 and 2022. In the case of BESI model, 69.23% and77.77% bank erosion sites are confined in high-to-extreme bank erosion susceptibility zones in the years 2020 and 2022. Therefore, BSEI model gives more precise results compared with BEHI due to three additional factors. The poorly sorted non-cohesive quaternary sediments stimulate high rate of bank erosion within Himalayan foreland basin.