Glacier elevation and mass changes in Himalayas during 2000–2014

Abstract. Glacier mass balance is a crucial parameter to understand the changes in glaciers. For the Himalayas, it is more complex as glaciers have a heterogeneous pattern of elevation and mass changes. In this study, mass balance using geodetic method is estimated, for which we utilize SRTM and TanDEM-X global digital elevation models (DEMs) of the year 2000 and 2012–2014 respectively. The unique feature of this study is that the dataset are prepared using repeat bistatic synthetic aperture radar interferometry which has not been used over the rugged Himalayan terrains on such a large-scale. The elevation and mass change measurements cover seven states namely Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Nepal, Sikkim, Bhutan and Arunachal Pradesh. The mean elevation change is −0.45 ± 0.40 m yr⁻¹ and the mass budget is −11.24 ± 0.79 Gt yr⁻¹. However, the cumulative mass loss over the observation period of 2000–2014 is −154.72 ± 19.04 Gt which accounts for approximately 5 % of the total ice-mass present in the Indian Himalayas. This ice-mass loss contributes to 0.42 ± 0.05 mm of sea-level rise. Validation of the mass balance estimate over 20 glaciers for which long-term ground observations were reported gave a coefficient of correlation of 0.79. These 20 glaciers are spread over the entire region of study. Such information shall be helpful in updating the current sparse database we have for the Himalayan glaciers and act as a piece of reliable information for developing various glacier-climate models in the near future.