Assessing the vulnerability of watersheds to environmental degradation in the lesser Himalayan region using satellite data and a series of models

Abstract

The Lesser Himalayan watersheds are vulnerable to environmental degradation due to their unstable lithology and anthropogenic pressure. A Gaula watershed was considered for the vulnerability analysis using satellite data, compound factor (CF) and multi-criteria decision making (MCDM) based on Grey Relation Analysis (GRA) and Complex Proportion Assessment of Alternatives (COPRAS) models. For prioritzation, 29 variables (12 morphometric, 5 geologies, 6 soils, 5 land uses/land covers, and 1 slope) were selected and the MCDM methods were validated using indices of the percentage of change and intensity of change. A total of five sub-watersheds (SW) were delineated, SW2 reported highest drainage density (0.58). The sinuosity index of SW1, SW4, and SW5 have 1.33, 1.34, and 1.27, showing active tectonic activities. The COPRAS reported highest intensity of change (93.33), whereas GRA and CF reported percentage of changes were 86.66 and 80.0, respectively. Hence, these models are appropriate to investigate the interrelationships of different components.