Glacier terminus retreat, mass budget, and surface velocity measurements for the Jankar Chhu Watershed, Lahaul Himalaya, India

Abstract. Characterization of glacier changes in the terminus, elevation, and surface velocity was worked out for the Jankar Chhu Watershed (JCW) of Lahaul Himalaya using freely available satellite remote sensing data and the limited number of field observations. We studied changes using Corona (1971), Landsat (1993–2017), Sentinel 2A (2016), the SRTM Digital Elevation Model (DEM; 2000), and the global TanDEM‒X DEM (2014). Change detection for nine select glaciers was studied in detail. Our results showed that changes in glacier terminus (−4.7 ± 0.4 m a⁻¹) between 1971 and 2016 are smaller than previously reported. An intricate pattern of mass changes across the JCW was observed, with surface lowering on an average of −0.7 ± 0.4 m a⁻¹ which equates to a geodetic mass balance of −0.6 ± 0.4 m w.e. a⁻¹ during 2000–14. The computed glacier surface velocities (1993‒2017) reveal nearly stagnant debris-covered ablation zone but the dynamically active main trunk. Field observations/measurements also support the findings. This study provides valuable insights into the recent glacier variations, which are of critical importance to assess the future glacier dynamics on a regional scale in areas like the present one. The dataset is freely accessible at http://doi.org/10.5281/zenodo.3383233 (Das and Sharma, 2019b).