Ice-flux divergence and strain rates reveal compressive-flow hotspots on Gangotri glacier

Abstract

Observation of glacier dynamics are critical for assessing hydro-climate processes in the high altitude regions of the world. This study investigated critical glacier ice parameters such as the ice flux divergence (IFD), surface mass balance (SMB) and the spatial pattern of ice surface deformation through logarithmic strain rate of the Gangotri glacier in the upper Bhagirathi basin using fully distributed models based purely on remote sensing data. The primary input for the investigations are based on the ice-thickness change rate, glacier velocity and the digital elevation model (DEM). The SMB referred to as the sum of the vertical and lateral changes of the glacier was observed to be 0.97 m of ice equivalent(m i.e.) yr 1 , indicating significance mass loss over the study period. The results derive several alignments with other published studies, and reveal key insights on the internal glacier processes through critical parameters such as highly variable longitudinal and shear strain rate indicated by standard deviations exceeding 0.025 yr 1 and 0.013 yr 1 , respectively. These highly variable and negative strain rates indicate significant compressive deformation of the glacier in certain regions of the ablation zone, resulting in ice cliffs and large crevasses that were observed in other studies.