Himalayan glaciers: combining remote sensing, field techniques and indigenous knowledge to understand spatio-temporal patterns of glacier changes and their impact on water resources

摘要

With contradictory statements about u22disappearing Himalayan glaciersu22 in the last few years, increasing concerns have been raised about the impact of snow and glacier changes on regional water supplies. Concomitantly, local communities in the western Himalaya report changes in glacier extents, snow cover and weather patterns. In response to perceived water scarcity, indigenous Himalayan cultures have begun a number of adaptive responses such as meltwater harvesting to construct u22artificialu22 glaciers. This research addresses the need for a detailed assessment of glacier and climate parameters in the Himalaya, with the goal of identifying u22at risku22 glacierized areas and helping these local communities plan future water resources. The objectives of the research are threefold: 1) to review existing knowledge about glacier fluctuations and remote sensing methods for glacier mapping in the Himalaya; 3) to quantify spatio-temporal patterns of glacier changes in the eastern Himalaya in the last decades using remote sensing techniques and field measurements and 3) to quantify the role of glacier melt to streamflow using a combination of remote sensing and isotopic techniques. This thesis focuses on the monsoon-influenced eastern Himalaya (the Langtang and Khumbu regions in the Nepal Himalaya, and Sikkim in the Indian Himalaya). The research is grounded in extensive field surveys conducted from 2006 to 2010 across the Himalaya, including glacier mass balance expeditions, water sampling, ground-control point (GCP) acquisition and GPS-enabled photos. The goal of this research is to understand how topographic and climatic factors influence the rates of glacier change at various spatial scales, and how these changes re likely to affect future water resources. Multi-temporal (decadal) glacier datasets were derived from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor, Landsat ETM+, older topographic maps, declassified Corona imagery and very high-resolution QuickBird and Ikonos imagery. I used a combination of visible, near infrared and thermal multispectral data combined with texture analysis and topography for glacier mapping. The results of this research help fill a gap in the understanding of glacier patterns in the data-scarce eastern Himalaya. The results of this research are useful for assessing vulnerability of the Himalaya to water scarcity due to future glacier or climate changes.