III-1-Gangotri Glacier Study using Remote Sensing, GIS and Long Term Temperature Data.

Abstract

In this study Gangotri glacier movement with respect to time as well as changes in the air temperature has been studied using remote sensing and climatic data. The multi-temporal mapping of the snout position using Landsat and Liss-III data and height with SRTM and ASTER GDEM is used to calculate retreating velocity of glacier. Monthly mean air temperature at 2 in above ground level has been used for climatic study. This data has been taken form NCEP/NCAR web site. The ortho-rectified images of Landsat MSS (1974, 1976, 1979, 1980), TM (1990, 1998), ETM+ (2002, 2003) and IRS-P6 Liss3 (2009) were used for snout position identification and supervised land use land cover classification. Thermal channel (band 6: 12.4-12.5 im) has been used in TM and ETM+ data for classification and snout position identification, Gangotri glacier is retreating by 16.56 in every year in horizontal (moving direction) axis, 0.82 m retreating by vertical axis (elevation) due to changes in air temperature, which is increasing 0.03"C every year. Also retreating velocity is increasing 1 in/year. Maximum speed observed from 1983 to 2003, in these 5 years speed was 23 m/ year and temperature also observed maximum (4"C in 1999). The glacier movement has also been studied using ERS1/2 tandem SAR data using interferometric techniques. Based on fringe analysis of main Gangotri glacier, the glacier movement has been found to of the order of 4-6cm per day or 16-21m per year.