DELINEATION RADAR ZONES OF GLACIERS IN THE ALA-ARCHA VALLEY OF KYRGYZ REPUBLIC

Abstract

: Glaciers are a critical source of freshwater, especially during the lean season. Globally, the glaciers are losing their mass balance rapidly under the influence of climate change. In view of this, the regular study of these glaciers is very vital. However, field-based studies of most of the glaciers is a daunting task. On the contrary, emerging geospatial technology may play an important role in the studies of glaciers. The equilibrium line altitude (ELA) of the glaciers has been considered an essential indicator of climate change. There are numerous methods to delineate the equilibrium line of a glacier; however, each has its own merits and demerits. In the present study, the synthetic aperture radar (SAR) remote sensing-based approach has been used for identifying the ELA of glaciers in the Ala-Archa River catchment of Kyrgyzstan from 2015 – 2019. Initially, the glacier radar zonesweremapped using the Sentinel-1 SAR datasets of each year under consideration. It was found that mainly the middle percolation, lower percolation, and bare-ice zones along with debris cover-ice are present in the glaciers. It was observed that the percolation refreeze zone covers approximately 40%, and the Bare-Ice zone covers 48% of the total area. Considering the boundary of lower percolation and bare-ice zone as ELA, the ELA of each glacier in each year was estimated. The lowest ELA of 3462 m was observed in 2018, whereas the highest (4309 m) was recorded in 2019. It was noticed that the trend of ELA is consistently increased from 3839.25 m in 2015 up to in 3868.29 m 2019. The temporal analysis of glacier radar zone estimation and ELA may help in studying the impact of climate change on glacier retreat and mass balance change. It can be concluded that geospatial techniques can make the glacier change studies possible without field survey. However, to validate the results of the study, field observations are a must.