Assessing controls on mass budget and surface velocity variations of glaciers in Western Himalaya

Shashank Bhushan,Debanjan Sinha,Anthony A Arendt,Tajdarul H Syed,Anil V Kulkarni

doi:10.1038/s41598-018-27014-y

Abstract

This study analyses spatially resolved estimates of mass budget and surface velocity of glaciers in the Zanskar Basin of Western Himalaya in the context of varying debris cover, glacier hypsometry and orientation. The regional glacier mass budget for the period of 1999–2014 is −0.38 ± 0.09 m w.e./a. Individual mass budgets of 10 major glaciers in the study area varied between −0.13 ± 0.07 and −0.66 ± 0.09 m w.e./a. Elevation changes on debris-covered ice are considerably less negative than over clean ice. At the same time, glaciers having >20% of their area covered by debris have more negative glacier-wide mass budgets than those with <20% debris cover. This paradox is likely explained by the comparatively larger ablation area of extensively debris-covered glaciers compared to clean-ice glaciers, as indicated by hypsometric analysis. Additionally, surface velocities computed for the 2013–14 period reveal near stagnant debris-covered snouts but dynamically active main trunks, with maximum recorded velocity of individual glaciers ranging between ~50 ± 5.58 and ~90 ± 5.58 m/a. The stagnant debris-covered extent, which varies from glacier-to-glacier, are also characterized by ice cliffs and melt ponds that appreciably increase the overall surface melting of debris-covered areas.

Highlights

Significant mass loss is evident over major glacierized regions in High Mountain Asia[1]
The Zanskar Basin is situated in the transition zone between the Karakoram Range and Western Himalaya (Fig. 1) and has significantly different climatic conditions when compared to other Himalayan regions
The Zanskar Basin lies in the rain shadow area of the Himalayan range[27] with most of the precipitation occurring in winter as a result of Mediterranean influences of the mid-latitude westerlies (MLW)[28]

Summary

Introduction

Significant mass loss is evident over major glacierized regions in High Mountain Asia[1]. Previous studies have indicated significant deviations in the mass budgets of glaciers, even within a single basin, which is controlled by different factors such as glacier hypsometry, orientation, extent of debris cover and surface velocity[12,13,14]. The most recent mass budget analysis of six selected glaciers in the Zanskar Basin including the Drung Drung Glacier, using the Equilibrium Line Altitude (ELA) and Accumulation Area Ratio (AAR) method, reported an overall gain in volume (~206.5 km3a−1) during the period of 2000–201029 This contradicts almost all previous estimates, which have reported significant glacier mass loss in the Western Himalaya[3,4,30]

Methods

Results

Conclusion