Modeling ice thickness distribution and storage volume of glaciers in Chandra Basin, western Himalayas

This article reports modeled ice thickness distribution and total ice volume of the 65 selected glaciers (> 0.5 km²) of Chandra basin, located in the Western Himalayas. This is a first-of-its-kind study that gives detailed insights about the current ice thickness distribution at an individual glacier level in the Western Himalayas. The estimates are obtained using an optimally parameterized GlabTop2_IITB Glacier Bed Topography Indian Institute of Technology Bombay (IITB) version model with high-resolution Digital Elevation Model (DEM) as an input. The total estimated volume of all the 65 selected glaciers is about 55.32 km³ covering a total area of about 591.03 km². Using hypsometric analysis, it is found that the maximum amount of ice volume, i.e., about 12.79 km^3, is currently residing at the elevation range of 5200–5400 m a.s.l. Ice thickness estimates obtained in the current study are compared with the ensemble estimates obtained in the Global Glacier Thickness Initiative (G2TI) project for three large glaciers, namely, Bada Shigri, Samudra Tapu, and Gepang Gath glaciers. The obtained results indicate that the difference between both the studies is marginal in terms of mean ice thickness and maximum ice thickness estimates except Samudra Tapu glacier. Moreover, the uncertainty of the estimated glacier ice volume from this study is about ±15% whereas, from the G2TI project, it is about 25%. The main reasons for the difference could be the quality of the inputs used, model structure, model parameterization as well as the time stamp of the input used. The obtained results from this study indicate that the use of appropriate shape factor and better DEM would result in more reliable glacier ice thickness estimates even by using a simple slope-dependent model like GlabTop2_IITB.