TR(BR)-1/2007 : Change estimation of selected western Himalayan glaciers

Abstract

Glaciers lay across the Himalayan arc at varying climatic and hydrologic regimes and response of these glaciers to the climate change vary accordingly. Glacier size, aspect, elevation range and slope are the other major factors influencing the rate of glacier change. This study report the change estimation of Batal glacier in the Chenab basin and Beaskund— I and Beaskund — II glaciers in the Beas basin since 1979/80. A glacier area - depth relationship has been established with the help of actual depth estimates of few glaciers carried out in previous studies by Ground Penetrating Radar (GPR). A comparison with other methods showed that the relationship developed for Tianshan region in China, which is widely used for ice volume estimate in the Himalayas, over estimate the ice volume by around 45%. During the past 26 years, area occupied by the Batal glacier has shrunk by about 0.29 km'. Major changes have been identified in the snout region. Glacier snout has receded by 670 m during this period at an average rate of 25.7 m per year. It is estimated that the Batal glacier had stored 195 MCM of water in 1979 which shrunk to 180 MCM in 2006, a loss of nearly 7% during the past 26 years.

Beaskund glaciers, the source glaciers of river Beas at its origin, are small glaciers and these glaciers have experienced highest changes during past 27 years. Area of Beaskund — I glacier has shrank by 37% and its aerial extent has reduced from 1.08 km' to 0.68 km'. This glacier has receded by 54 m at the frontal area during the period at the rate of 2.0 m/yr. Most significantly, volume of this glacier has reduced by 43% during this period, and substantial reduction in the length has occurred in the highest elevation in the accumulation zone of the glacier. This suggests that small glaciers occupying low altitude could shrink from all its peripheries. Change in the aerial extent of Beasktmd — II glacier during 1979 -2005 period amounts to 29.8%. Its area has reduced from 1.31 km2 to 0.92 km" and this glacier has receded by 197 m during the period at a rate of 7.0 m/yr and volume of the glacier has reduced by 34.8% during this period. This study also report the ongoing process of detachment of glacier ablation zone from the accumulation zone in Batal and Beas Kund — II glaciers suggesting thinning of the accumulation zone. This is a clear signal of accelerated glacier degradation happening in this region. This study suggests that small glaciers, with their smaller response time, are the most vulnerable to the changing climate.