Topographical and morphological variability explicates the regional heterogeneity in glacier surface ice velocity across Karakoram-Himalaya

Abstract

Understanding the implications of variations in glacier surface ice velocity (SIV) has become an essential component of glacier research and monitoring. This study investigates the variability in SIV with respect to geography, morphology, and topography in Karakoram-Himalaya. SIVs are extracted for 1439 glaciers in the Karakoram-Himalaya region for the period 2016–2019 using Landsat-8 datasets and a feature tracking method. Glaciers are categorized based on their area, ice thickness, and ice volume in order to investigate the SIV variability with geographical, morphological, and topographical parameters. We highlight regional heterogeneities in glacier SIV across the Karakoram-Himalaya. We conclude that in addition to glacier morphology, the altitudinal heterogeneity of glaciers in the Karakoram-Himalaya best explains regional disparities in glacier SIV. For all glacier areas smaller than 20 km2, a significant negative correlation (less than −0.4) is observed between glacier minimum elevation and SIV. Heterogeneity in the role of elevation on SIV is also observed at the sub-basin scale, with a correlation of −0.47, −0.33, and −0.18 in the Hanza, Chenab, and Kosi sub-basins, respectively. An unsystematic variability of SIV for large glaciers (area >20 km2), located mostly in the Karakoram and Western Himalayan regions, suggests that the elevation and sub-glacial hydrology may have a significant impact on their dynamics.