Assessment of Eastern Himalayan Glacier Cryo-facies: A Case Study of Teesta Basin, Sikkim Using Satellite Image Classification Technique
摘要
The Eastern Himalayan glaciers, particularly, are indispensable sources of freshwater, nourishing major rivers such as the Brahmaputra, Ganges, Yangtze, Ranjeet, and Teesta, and supporting drinking water supply, agriculture, and hydropower generation in numerous regions. This study hones in on the estimation of glacier cryo-facies features for 10 selected glaciers of Teesta basin in the Sikkim region, namely, Changme, Changsang, Lhonak, North Lhonak, Onglangthung, South Lhonak, Teesta Kangse, Zemu, G088187E27874N, and G088217E27252N. The analysis leverages multispectral data from Landsat-8 spanning the years 2021 and 2022. The application of Maximum Likelihood Classification (MXL) facilitates the estimation and evaluation of glacier cryo-facies, a statistical supervised classification method that allocates each pixel to the most probable category based on its spectral values. The identified cryo-facies include wet snow, dry snow, bare ice, debris, and shadows. The comparative analysis of 2021 and 2022 reveals a conspicuous reduction of dry snow region by 22 km2 and concurrent increases in wet snow region by 16.3 km2, bare ice region by 5.9 km2, and debris region by 1.3 km2. These observations underscore the phenomenon of deglaciation, signaling significant changes in glacier cryo-facies and their environmental implications in the study region.