Morphometric Analysis and Prioritization of Watersheds for Flood Susceptibility Mapping in the Eastern Himalayan Foothills, India

Abstract

Flood vulnerability mapping is a significant footstep for policymakers for disaster management and water resource management and restoration. In this chapter, we analyzed the morphometric parameters sub-watersheds prioritization (MPSWP) of the Kaljani River Basin for flood susceptibility zone identification. Characteristics of this Himalayan foothills river are a sixth-order drainage system, a dendritic drainage pattern, and a funnel-shaped basin. This present chapter has integrated with morphometric analysis using ALOS PALSAR DEM (12.5 m) for assessing the flood susceptibility area spatially. We have used the total ranking approach for the final flood susceptibility sub-watershed prioritization. Research findings show that about 40.62% area of the basin and 11 sub-watersheds were identified as high to very high flood susceptibility zone. Out of the 12 morphometric factors, five factors (Rr, Rv, Sf, Lo, and Rn) were the most significant factors for the flooding. The receiver operating characteristic (ROC) curve was employed for the validation of the model. The result of the ROC accuracy rate is 87%. Therefore, MPSWP has been successfully and efficiently employed to determine sub-watershed sensitivity to flooding. This result can be helpful as a primary guideline for flood mitigation and sub-watersheds management.