GIS-Based Morphometric Analysis and Prioritization of Upper Ravi Catchment, Himachal Pradesh, India

Abstract

Morphological parameters have been recurrently used to assess the hydrological response of a watershed. Due to a strong mutual correlation between the run-off characteristics and the terrain of a watershed, the method is significantly popular, especially in an un-gauged catchment. In the present study, the hydrologic response of a Himalayan watershed and its sub-watersheds is discussed using various morphological parameters, and accordingly, the sub-watershed prioritization has been done. Morphological parameters have been extracted from digital elevation model (SRTM-DEM) in conjunction with Survey of India toposheets (1:50000 scale). Arc Hydro tools have been used for the preparation of watershed and sub-watershed boundaries, to calculate flow directions, flow accumulation and for stream ordering. Morphometric parameters categorized under linear, aerial and relief aspects are calculated for the entire catchment and also for its eight sub-watersheds separately. The drainage pattern is mostly sub-dendritic to dendritic in nature. The studied catchment has been categorized as an eighth order drainage catchment with a drainage density of 3.15 km/km2. The progressive increase in stream length ratio is a depiction of the attained geomorphic maturity of the basin. Considerable conformity between the sub-watersheds and their major catchment characteristics has been established. However, two sub-watersheds have been observed to behave in a different manner. In order to prioritize the catchment, a compound index was calculated by considering the individual rank assigned to all eight sub-watersheds based on 11 morphological parameters. The study reveals that SW6 sub-watershed has the highest priority and SW2 watershed has the least priority. Such maps have immense significance for field engineers for prioritizing the watershed management activities within the watershed especially in un-gauged condition.