Monitoring spatio-temporal glaciers retreat and advances in Bhagirathi Basin, Gharhwal Himalayas using Remote Sensing Data

Abstract

Abstract In this study, 29 glaciers of the Bhagirathi basin, Garhwali Himalayas, have been monitored using remote sensing (RS) satellite images for more than a decade. Bhagirathi basin has sub-basins, namely Bhagirathi, Bhilangana, Pilang, Jahnvi, Jalandhari, and Kaldi. The glaciers area > 5 km2 has been considered apart from a few small glaciers to estimate glaciers retreat and advances. Landsat satellite images of 2000 and 2015 have been used to estimate areal extent change in glaciers. ASTER DEM has been used for extraction of glaciers terrain features such as elevation, slope, area, etc. It is observed from the analysis that Bhagirathi sub-basin has a maximum glaciated area of ~ 35% and Pilang has the least with ~ 3.2%, whereas Kaldi sub-basin has no glacier. In this region, out of 29 glaciers, 25 glaciers have shown retreat while 4 glaciers have shown advancement and resulting the total glacier area loss of ~ 0.5%, while the retreat rate varies from ~ 0.06 m/yr to ~ 19.4 m/yr. Dokarni glacier has maximum retreat rate (~ 19.4 m/yr), whereas, Dehigad has maximum advancing rate (~ 10.1 m/yr). Glaciers retreat and advance have also been analysed based upon terrain parameters and observed that north and south aspect orientations have shown retreat, whereas the area change is highly correlated with glacier length. The study covers more than 65% of the total glaciated area and as per our knowledge based on the existing literature; this is one of the initial exhaustive studies to cover the highest number of glaciers in all sub-basins of the Bhagirathi basin.