Assessment of recent changes (2011-2020) in glacier thickness and runoff variability in Gangotri glacier, India.

Recent evidence shows a noticeable reduction in the glacier mass in the Himalaya due to increasing temperatures, and therefore the downstream water availability is becoming uncertain. This study analyse the effect of changes in the Gangotri glaciers (i.e. thickness), including Raktavaran and Chaturangi regions, on the melt runoff (2011-2020) by coupling two models: Glacier Bed Topolology (GlabTop2) and Spatial Process in Hydrology (SPHY). This study performs the two-step calibration approach utilizing the observed discharge and Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover data. The R² values for SPHY-modelled runoff (Q) and observed Q at Bhojwasa are found comparable (~0.73 on a daily scale) and the proportions of glacier Q and snow Q in total Q are computed as 22.11% and 66.91%, respectively. In comparison to Chaturangi and Raktavaran, Gangotri glaciers experienced a higher rate of change in thickness, and a reduction of ~9.40% in the mean glacier thickness is calculated during 2011-2020. [ABSTRACT FROM AUTHOR]