Hydrologic response of Beas river basin in the fragileHimalayan ecosystem based on morphometric analysisusing Google earth engine

Abstract

Understanding the hydrologic response of a river basin is essential for evaluating water resource potential and environmental sustainability, especially in fragile mountain ecosystems. The present study investigates the hydrologic behavior of the Beas river basin, situated in the northwestern Himalayan region of India, through morphometric analysis using high resolution Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) DEM at 12.5 m within Google Earth Engine (GEE) environment. The basin covers an area of approximately 19338 km2, exhibiting a wide elevation range from about 159 m in the foothills to over 6,570 m in the upper Himalayas. Land use analysis revealed that 45.12% of the area is occupied by forest cover, while 29.95% is under agricultural land. The drainage network is of seventh order, comprising 4126 identified streams, of which 3120 are first-order streams, with a total stream length of 12287.50 km. The basin displays a dendritic drainage pattern, characterized by a stream frequency of 0.21 and a mean bifurcation ratio is 3.98. The drainage density (0.64) signifies moderate vegetation and semi-permeable rocks, while the very coarse drainage texture (3.21) suggest the occurrence of sharp storm hydrographs with short duration peaks, leading to intense soil erosion within the river basin. Furthermore, morphometric indices such as the form factor (0.23), circularity ratio (0.15), and elongation ratio (0.27) indicate that the basin exhibits a moderately elongated shape with medium to high relief and moderately permeable sub-soil conditions. These characteristics collectively imply moderate runoff and peak discharge, which contribute to significant soil erosion and siltation issues in existing water harvesting structures. The present study provides valuable baseline information for watershed prioritization, soil and water conservation planning, flood risk mitigation and sustainable water resource management in Himalayan region.