Identification of erosion-prone areas using morphometric parameters, land use land cover and multi-criteria decision-making method: geo-informatics approach

Soil erosion is the main driving force of several devastating natural hazards in the complex mountainous terrain of the Himalayas where the Teesta River basin is located. The present study focused on GIS-based multi-criteria analytical approach (MCA) that integrates morphometric parameters with land cover categories for identification of erosion hotspot areas through sub-watersheds prioritization. The general character of the eight sub-watersheds was derived from the linear, areal and relief aspects, while seven land cover types derived from maximum likelihood classification were evaluated in the MCA. Before combination of the studied parameters in MCA, each parameter was individually ranked and compound value (Cp) was calculated which produced four classes: low, medium, high and very high priority. Later, these ranks were integrated into MCA to give eight major classes classified from 1 to 8. Lowest Cp ranked 1 gets very high priority, while the highest Cp is ranked 8, i.e., lowest priority. The results revealed a predominance of dense forest account for 31.73% of the total area, the basin is a sixth-order river dominated by high relief and marginal slope, elongated in shape, and mean bifurcation ratio (Rb) was 3.879 which indicates an undistorted natural drainage system. Final MCA priority ranking indicated that: SW-4 and 5 having lowest Cp values (3.39 and 4) ranked 1 and 2 suggest very high erosion susceptibility, SW-8 and 3 (4.22 and 4.39) rated 3 and 4, i.e., high priority; SW-6 and 7 ranked 5 and 6, i.e., medium priority; and SW-1 and SW-2 ranked 7 and 8 because of their highest Cp (5.39 and 5.67), i.e., least priority. The prioritization result identified critical areas that are indispensable for sustainable use and management of water and land resources.