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.
