Watershed Prioritization Using Saaty’s AHP Based Decision Support for Soil Conservation Measures

Abstract

The identification of environmentally stressed areas for planning soil conservation measures requires an efficient decision support tool to provide appropriate weights for various topographical, morphological, climatological and management factors responsible for soil erosion. In the present study, Saaty’s analytical hierarchy process (SAHP) with nine erosion hazards parameters (EHPs) including soil loss (SL), sediment yield (SY), sediment production rate (SPR), sediment transport index (STI), slope (Slp), Drainage density (D d ), channel frequency (Cf), form factor (R f ), circulatory ratio (R c ) has been used as a decision support system for identification of environmentally stressed sub-watersheds in Benisagar dam catchment of Bundelkhand region (Madhya Pradesh, India). The SAHP is a structured technique for dealing with complex decisions which involves building a hierarchy of decision elements, making comparisons between each possible pair in each cluster, provides weighting for each element within a cluster and checking the consistency of the decision based on a consistency ratio. The Benisagar dam catchment having excessive erosion due to undulating topography, limitation of soil depth and absence of conservation measures affects reservoir storages due to silting problems. For prioritization purposes, the Benisagar dam catchment has been divided in to 36 sub-watersheds with their areas ranging from 0.77 to 6.53 km2 and all nine EHPs for various sub-watersheds have been computed. The pair wise comparison matrix and final weights for all the EHPs have been determined using SAHP with the acceptable limit of consistency ratio. The final priority ranks for sub-watersheds have been computed by summing the multiplication of SAHP weights and their corresponding normalized values of EHPs. From the analysis, it has been observed that eight sub-watersheds covering 20.15 km2 and seven sub-watersheds covering 19.41 km2 areas fall under very high and high priority respectively.