GIS-based spatial multi-criteria approach for characterization and prioritization of micro-watersheds: a case study of semi-arid watershed, South India

Abstract

An assessment of micro-watersheds based on topography and physical processes is always helpful in identifying suitable locations for implementing soil and water conservation measures. The present study was taken up with the objectives of characterization and prioritization of micro-watersheds using GIS-based spatial multi-criteria approach for a case study area of Andipatti watershed. In order to characterize the micro-watersheds, measurements derived from linear, areal, and relief aspects of the stream network were primarily used as indicators of topography and physical processes. To compute a comprehensive value for each micro-watershed, values of morphometric parameters viz., bifurcation ratio (Rb), drainage density (Dd), stream frequency (Fs), drainage texture (Rt), elongation ratio (Re), circularity ratio (Rc), length of overland flow (Lg), and relief ratio (Rh) were used. Further, quantitative estimation of annual average rates of soil erosion (SE) through the RUSLE method and surface runoff (SR) thorough NRSC-CN method was also integrated with micro-watersheds for ranking purposes. To normalize the rankings of each spatially distributed parameter, weights were derived through the analytical hierarchy process (AHP). Finally, the weighted rankings were summed up and all micro-watersheds are categorized into four priority classes viz. very high, high, moderate, and low. Out of 44 micro-watersheds, 16 micro-watersheds fall under very high priority class signifying the need for watershed conservation measures. Based on the priority index, suitable structural and non-structural measures are suggested to the vulnerable watersheds.