Scanning Debris-Covered Glaciers and GLOFs in Khumbu, Nepal, by Jeff LaFrenierre

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Debris-cover is a common feature in the ablation areas of large valley glaciers in mountain areas around the world, and its presence has important implications for a glacier's response to changing climatic conditions and for its potential for generating environmental hazards such as glacier lake outburst floods (GLOFs). Debris-cover of even modest thickness insulates the ice surface, slowing rates of ablation and permitting the maintenance of glaciers at lower elevations than local temperatures and precipitation rates would otherwise support (Ostrem 1959; Nakawo et al. 1999; Shrader et al. 2000). Debris-cover also preserves large areas of stagnant, or "dead" ice at the lowest reaches of large glaciers, where lakes may form during periods of extended negative mass-balance, meaning that the moraines damming such lakes are often ice-cored and thus subject to morphological change as the ice slowly melts. This, in turn, suggests that the stability of such lakes and their potential for catastrophic release is partly a function of the rate at which the debris-covered glaciers are ablating. Measuring the mass-balance of debris-covered glaciers is, however, more difficult than that of "clean-ice"-type glaciers and, despite the clear need to monitor rates of change on such features, efforts to do so remain relatively limited. This brief paper describes the presence of debris-covered glaciers in the Khumbu Himalaya region traversed by 2011 Andean-Himalayan Glacial Lake Exchange and Collaboration Expedition, the challenges of monitoring change on debris-covered glaciers and potential tools for doing so, and outlines the potential utility of laser scanning technologies in particular for assessing GLOF risk in the region.

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