Abstract: Snow and ice meltwater account for more than 30% of the total runoff in the Brahmaputra River basin,making quantitative research on the spatio-temporal distribution of snow cover highly significant for the construction and operation of hydropower projects.This study employed a downscaling approach utilizing snow cover fraction data to reconstruct low-resolution snow depth products.Based on the downscaled data,the spatio-temporal distribution and variation characteristics of snow depth in the Brahmaputra River basin from 2000 to 2019 were analyzed,and the influences of topographic and climatic factors on snow depth were further examined.The results reveal a significant decreasing trend in snow depth across the basin during 2000—2019,with notable spatial heterogeneity.Deep-snow areas were more sensitive to climate change.Among topographic factors,elevation and slope significantly influenced snow distribution,while aspect had a relatively limited impact.Snow depth exhibited a stronger response to precipitation changes than to temperature variations.The findings of this study provide a scientific basis for optimizing the operation of hydropower systems and assessing snow and ice resources under climate change in the Brahmaputra River basin.

Key words: microwave remote sensing, Brahmaputra River basin, snow depth, downscaling