Analysis of the temporal variations in glaciers’ surface area in Alaknanda River Basin, Uttarakhand

Abstract

This study presented detailed analysis of glacier surface extent in the Alaknanda river basin, Western Himalaya, using Landsat series data, land surface temperature and digital elevation model (DEM). The clean glaciers were delineated using automatic glacier extraction index (AGEI) and the debris-covered glaciers were extracted by utilizing slope and land surface temperature. The generated glaciers map was com-pared and cross-checked with Randolph Glacier Inventory (RGI v5.0) and sharp google earth image. The reduction in glacier surface area was observed by 367.364 sq. km from 1994 (1150.471 sq. km) to 2015 (783.107 sq. km) at the shrinkage rate of 1.45% per annum. The shrinkage rate was higher from 2006 to 2015 (2.43% per annum) than from 1994 to 2006 (0.78% per annum). The glacier count expanded from 314 (1994) to 360 (2015) due to the fragmentation of individual glaciers. The elevation range of 5000–5500 m above m.s.l. hosted maximum number of glaciers and glacial coverage. The debris-covered glaciers showed deglaciation at the rate of 0.59% per annum from 1994 to 2015. The total area occupied by glacier extent was about 25% of the total basin in the year 1994, 23% in the year 2006 and 17% in the year 2015.