Comparative Assessment of Volume Change in Kolahoi and Chhota Shigri Glaciers,Western Himalayas,Using Empirical Techniques

Abstract

Volume change in glaciers across the world is an established fact; however, response of Himalayan glaciers to climate change is not well understood. Looking at the importance of volumetric information of glaciers, glaciologists use different methods of volume estimation e.g., geophysical methods including GPR surveys, seismic profiling and tomography; glaciological methods by installing stakes and empirically established scaling methods. However, considering the difficulty in field measurements associated with Himalayan glaciers, indirect assessment techniques are being used widely. The objective of this study was to compare the response of two most studied western Himalayan glaciers i.e. Kolahoi glacier and Chhota Shigri glacier over the last three to four decades using empirical relationships of glacier volume estimation. The factors such as glacier length, area and slope were extracted from satellite data and digital elevation models. Glacier area change for Kolahoi glacier and Chhota Shigri glacier was mapped from 1980 to 2015 using Landsat images. The analysis of data showed that the areal extent of glaciers has receded from 1980 to 2015.

Three scaling laws applied in this study yield different volume estimates for the glaciers from two adjoining sub-basins of the Indus basin, western Himalaya. The glaciers reported in this study show –10% (Kolahoi glacier) and –2.6% (Chhota Shigri glacier) change in their length and –13.5% (Kolahoi glacier) and –2.1% changes in the areal surface during the study period of 35 years. Cumulative change in volume estimated using different methods was found to be comparable i.e., –18% for Kolahoi and –3% for Chhota Shigri glacier, during the study period. However, progressive change in volume of two glaciers shows slight difference—Kolahoi glacier is declining rapidly as compared to Chhota Shigri glacier. Incorporation of field measurements into satellite data analysis, and their comparison strengthens the estimates of pattern in ice volume variability. The study tried to identify parallels and differences in the melt response of two most studied glaciers in Indus basin, based on available satellite images.