Quantitative morphometric analysis and prioritization of sub-watersheds for soil erosion susceptibility: A comparison between fuzzy analytical hierarchy process and compound parameter analysis method

Abstract

Identification of critical sub-watersheds susceptible to soil erosion risk is the preliminary step in any watershed management plan. To achieve this goal, the prioritization of sub-watersheds based on morphometric characteristics is of paramount necessity. This study was performed on the Upper Shimsha-1 watershed using DEM to quantify the morphometric parameters in a GIS environment. The stream network was extracted in ArcGIS software, and the watershed was delineated into 16 sub-watersheds (SW1 to SW16). Two approaches, viz., the fuzzy analytical hierarchy process (FAHP) and compound parameter analysis methods, were employed in prioritizing sub-watersheds using 18 parameters highly related to soil erodibility. The FAHP score ranged from 0.145 (lowest priority) to 0.794 (highest priority), prioritizing sub-watersheds into ‘high’, ‘medium’ and ‘low’ classes occupying 10.76%, 27.23% and 62.01% of the total area, respectively. The compound parameter values ranged from 6.05 (highest priority) to 10.77 (lowest priority), and the ‘high’, ‘medium’ and ‘low’ classes occupied 31.84%, 16.49% and 51.67% of the total area, respectively. The common sub-watersheds from both methods under the ‘high’ priority class were SW14 and SW15, accounting for 10.76%, and under the ‘low’ priority class, SW1, SW8, SW9, SW11, SW12 and SW16 accounted for 42.66% of the total area. Hence, eight sub-watersheds were common in both prioritization methods corresponding to their respective priority classes. The integration of GIS technology, morphometry and prioritization methods has proven to be indispensable in watershed management and soil conservation efforts through this investigation. It further emphasizes the need for swift attention from decision-makers toward critical sub-watersheds.