Assessing the Snow Water Equivalent Dynamics of the Brahmaputra River Basin

ABSTRACT The Brahmaputra River Basin holds a crucial position in South Asia’s hydrological framework, serving as a vital source of water for a substantial population. Snow Water Equivalent (SWE), a pivotal metric reflecting water availability in regions dominated by snow, assumes a significant role in shaping the hydrological cycle of the basin. Thus, this present work aims to conduct a comprehensive study of the SWE dynamics across the Brahmaputra River Basin from 1980 to 2021. The present study obtains the data of elevation, ERA5-Land and SWE and SWE maximum, snowfall, snow cover area, snow depth, and air temperature, in a Geographic Information System (GIS) environment. Seasonal and annual trends are analyzed using the Theil-Sen slope estimator and the Mann-Kendall significance test. Correlations and linear regressions are conducted to assess the relationships among the variables. The findings unveil intricate SWE distribution patterns across the study area, with high elevations exhibiting prolonged snow cover area and substantial SWE values. Trend analysis shows a consistent decrease in SWE and SWE maximum across all seasons, ranging from -0.006 (post-monsoon) to -0.034 m (pre-monsoon) water equivalent/decade. Similarly, a declining trend (at a rate of -0.014 m water equivalent/decade) is also observed in annual SWE. The declining seasonal and annual SWE is possibly linked to escalating air temperature, diminishing snowfall, snow cover area, and snow depth during the study period. The implications of these findings underscore the significance of incorporating SWE variations into water management and the assessment of ecosystem health in the region.