Monday, August 26, 2013

Glacial and Sediment Hazards in the Rolwaling Valley, Nepal

Glacial lake outbursts are a major hazard in the South Asian Himalaya and other glacier regions of the world. Climate change and glacier retreat have heightened the danger of outburst events, as new glacial lakes have formed and expanded. The outburst discharge from glacial lakes may cause catastrophic flooding and damage in downstream areas. It is thus important to investigate the impact of climate change on glacial lakes and to understand lake behavior. This study examined glacier- and sediment-related hazards in the Rolwaling Valley of Nepal, and field-assessed the Tsho Rolpa glacial lake in the valley. Potential causes of moraine dam failure at Tsho Rolpa include overflow and erosion of the dam caused by ice or boulders falling into the lake, seepage inside the dam, melting of the ice core inside the dam, or an earthquake. The peak outburst discharge from Tsho Rolpa was estimated to range from 7,759 to 90,296 m3/s using different empirical equations. The resulting flood would cause serious damage up to 100 km or more downstream, threatening many people, agricultural lands, forests, hydroelectric projects, and other infrastructure.

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