Prioritization and identification of vulnerable sub-watersheds using morphometric analysis and an integrated AHP-VIKOR method

Abstract

This study used satellite imagery datasets to extract various morphometric parameters in a geospatial environment to prioritize problematic areas in the Rarhu watershed of Ranchi district, Jharkhand, India. Two decision-making methods, the analytical hierarchy process (AHP) and VIKOR (VIseKriterijumska Optimizacija I Kompromisno Resenje), were integrated to prioritize different sub-watersheds. The Rarhu watershed has an area of 630 km2 with an elevation ranging from 210 to 824 m. The NASA Digital Elevation Model (NASADEM) was used to extract drainage networks which were verified from Survey of India (SOI) toposheets. To prioritize 21 sub-watersheds using a multi-criteria decision making (MCDM) method, 11 morphometric parameters were selected from linear, areal, and relief parameters. The VIKOR method prioritized sub-watersheds using AHP criteria weights, which are classified into four priority levels ranging from very high to low. In addition, performing sensitivity analysis validated the robustness of the decision-making model. As per the analysis, Rarhu watershed was found to have an elongated shape and a highest 6th order stream with a dendritic pattern of streams. It is estimated that watershed degradation is around 36.17% in the study area, with very high priority needs for soil and water conservation measures. Using the results of the study, policymakers, watershed planners, watershed development programme, and soil and water conservation programme projects can identify vulnerable subwatersheds that require urgent adaptation of soil and water management control measures.