Morphometric characterization and prioritization of sub-watersheds for assessing soil erosion susceptibility in the Dehar watershed (Himachal Himalaya), Northern India

Soil erosion is a key environmental issue in the geologically sensitive zone of the lower Himalaya. Watershed as a hydrological unit plays an important role in the conservation of such a perishable resource. Morphometric parameters are found to be indispensable elements in the hydrological characterization of a watershed. The morphometric prioritization is considered to be a more suitable approach than any other prioritization techniques to assess the erosional constraints including sustainable soil resource planning and management practices. Keeping this in view, the current study was taken-up for priority ranking and categorization of eight sub-watersheds of the Dehar watershed of the Beas river system, positioned in the tectonically fragile and erosion-prone zone of the Himachal Himalaya using the weighted sum analysis method. Geospatial techniques, including remote sensing and geographic information system combined with statistical methods, were applied to support precision prioritization and fixing of the inaccurate results instead of other traditional methods of prioritization. By considering the weighted sum analysis technique, the eight sub-watersheds of the Dehar watershed were divided into very high, high, medium, and low categories of prioritization. The study further revealed that four sub-watersheds, which cover half of the entire basinal area (53.06%), fall under very high (46.06%) to high (7%) category zones for prioritization. There is an urgent need for more effective preferential treatment practices that may be adopted through the soil and water conservation techniques, which in turn will also address the siltation problem of the Maharana Pratap Sagar/Pong reservoir situated on the Beas River system. Through this study, it is also inferred that the weighted sum analysis technique is more useful in undertaking watershed analysis in the Himalayan region and certainly, improves the understanding and decision-making priorities of different stakeholders associated with water and soil resources conservation practices, planning and management programs.