Spatiotemporal Assessment of Baltoro Glacier Snow-Cover Dynamics: Relevance to Indus Basin Water Resources and Irrigation

Abstract

Glaciers of the Karakoram feed the Upper Indus, whose meltwater supports one of the largest irrigation systems in the world and, through it, the soils and crops of Pakistan. This study assessed the change in snow-covered surface of Baltoro Glacier between 2000 and 2020 and tested its relationship with temperature and precipitation. Landsat 5, 7 and 8 imagery was classified with the Normalized Difference Snow Index (NDSI) in ArcGIS, and climate data (2000-2020) were obtained from NASA POWER (MERRA-2) for the glacier grid cell (35.92° N, 74.30° E; mean elevation 3,627 m). Snow-covered area declined by 9 percentage points between December 2000 and December 2020 and by 13 percentage points between August 2000 and August 2020 (mean 11). Annual loss increased significantly through time (0.041% yr⁻¹; r = 0.79, p < 0.001) and averaged 0.30% yr⁻¹ in 2000-2012 compared with 0.89% yr⁻¹ in 2013–2020. Simple linear regression showed positive but statistically non-significant associations of snow-cover loss with temperature (R² = 0.034, p = 0.43) and precipitation (R² = 0.056, p = 0.30). The modest overall loss is consistent with the Karakoram anomaly and the insulating effect of supraglacial debris, whereas the late-period acceleration warrants monitoring because changes in glacier snow cover may have implications for downstream water resources, including irrigation, soil moisture and salinity management.