Volume Estimation of Glaciers in Alaknanda Sub-basin.

Glacier volume estimation is an essential aspect of conducting studies on glacier health. In past decades, various approaches relying on Volume-Area (V-A) scaling or ice thickness distribution have developed. Demonstrative research is attempted for volume estimation of glaciers present in Alaknanda, a Himalayan sub-basin of river Ganga with an area ≥ 1 km² for 2017. Approaches relying on V-A scaling relations, glacier velocity and basal shear stress are used for the volume estimation of 158 glaciers. The study focuses on the variability of input parameters instead of uncertainty assessment. The estimated 1-σ volume based on V-A scaling relations ranges from 54 to 89 km³, 57 to 68 km³ for the velocity-based approach and 59 to 74 km³ for the GlabTop2 model. The average thickness of all glaciers lies between 61 to 77 m and 63 to 85 m using the velocity-based approach and Glabtop2 model respectively, for different values of shape factor (f ). The maximum thickness estimated for the velocity approach and GlabTop2 model is 268.41 m and 290.33 m, respectively while for available ensembled ice-thickness data, it is 287.22 m. The average flux calculated for all glaciers in the region is 847.12 m²/year. On examining, the volume of individual glaciers for various approaches, only the GlabTop2 model deviates. As per area-wise glacier classification, glaciers greater than 10 km², contributes ∼ 54% in total area with volume contribution of ∼ 68% for both ensembled thickness and V-A scaling relations, ∼ 58% for the velocity-based approach, and ∼ 55% for GlabTop2 approach. The ice-thickness distribution of large glaciers for the GlabTop2 model is low compared to other smaller glaciers. Bhagirath-Khark and Satopanth glaciers when examined for various approaches, the estimated ice-thickness and volume contrasted for the GlabTop2 model. However, when Satopanth glacier is studied solely, the latter results are in good agreement. Elevation-based hypsometry analysis is also performed, and investigated for glacier area, velocity and volume. [ABSTRACT FROM AUTHOR]