ANNOUNCEMENTS
Understanding the changes in Himalayan glaciers is of importance for assessment of the future water availability and early detection of trends related to the anthropogenic greenhouse effect. Terrain of eastern Himalayan glaciers is much more difficult in comparison to western and central Himalayas. For this reason long term field based measurements are not available for the glaciers of this region; therefore, Sikkim has been chosen as the study area in this thesis. Remote sensing methods have been used in this study because glaciers in this region are difficult to reach. Understanding of the problem was built and objectives were formulated for the study after studying East Rathong glacier located in Sikkim.
Three objectives have been formulated. The first objective is to estimate and reconstruct mass balance series with specific reference to East Rathong glacier, using off-field methods. To fulfill this objective, mass balance, ablation, accumulation, glacial melt and runoff for the glacier have been estimated for the time period 1963-2011 using off-field methods. A mass balance model has been proposed for the glacier. Second objective is to estimate the volume of glaciers in Sikkim with specific reference to East Rathong glacier and study the variability in the results from different methods of volume estimation. To fulfill this objective, volume of East Rathong glacier was estimated using on-field and off-field methods. Then volume of other 424 glaciers was estimated using off-field methods. Mass balance of the glaciers is also estimated for the time period 2010-2014. The study suggests that glaciers are a good proxy for climate change studies. Third objective is to study the regional climate of Sikkim Himalaya using multi-satellite data sets, and assess its impact on the glaciers. To fulfill this objective an attempt has been made to capture the sensitivity of a mountainous region to elevation-dependent warming and the response of a glacier-laden surface to increasing greenhouse gases (GHGs) and aerosol concentration. The main inferences drawn while addressing the third objective are that it is important to carry out rigorous studies related to aerosols-cloud interaction and their impact on precipitation and glacier-melt patterns over Himalayan region; regions dependent for their water needs on eastern Himalayan glaciers will soon have to adapt to the use of scarce water resources; river flow reduction would come sooner as glacier area and volume are reduced more rapidly due to increasing air pollution; better predictive tools for factors affecting glacier melt rates are urgently needed for planning for climate change adaptation.
The study demonstrates that even without the support of field data, remote sensing and Geographical Information System (GIS) can be effectively used for the glacier studies.
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