Identification of glacier motion and potentially dangerous glacial lakes in the Mt. Everest region/Nepal using spaceborne imagery

Abstract

Abstract. Failures of glacial lake dams can cause outburst floods and represents a serious hazard. The potential danger of outburst floods depends on various factors like the lake's area and volume, glacier change, morphometry of the glacier and its surrounding moraines and valley, and glacier velocity. Remote sensing offers an efficient tool for displacement calculations and risk assessment of the identification of potentially dangerous glacial lakes (PDGLs) and is especially helpful for remote mountainous areas. Not all important parameters can, however, be obtained using spaceborne imagery. Additional interpretation by an expert is required. ASTER data has a suitable accuracy to calculate surface velocity. Ikonos data offers more detail but requires more effort for rectification. All investigated debris-covered glacier tongues show areas with no or very slow movement rates. From 1962 to 2003 the number and area of glacial lakes increased, dominated by the occurrence and almost linear areal expansion of the moraine-dammed lakes, like the Imja Lake. Although the Imja Lake will probably still grow in the near future, the risk of an outburst flood (GLOF) is considered not higher than for other glacial lakes in the area. Potentially dangerous lakes and areas of lake development are identified. There is a high probability of further lake development at Khumbu Glacier, but a low one at Lhotse Glacier.

A multi-level strategy for anticipating future glacier lake formation and associated hazard potentials

“…The different lake formation processes explain the differences of the slope values for level 1: on debris-covered tongues, lake formation normally starts with the occurrence of small individual supraglacial ponds that coalesce later to a single lake, which finally grows constantly by melting the adjacent ice in all directions (mainly upstream). This process can take the whole valley width and finally even replace a large part of the tongue (Bolch et al, 2008;Komori, 2008;Watanabe et al, 1994). Our approach is related to proglacial lake formation at (nearly) debris-free glaciers where lake formation starts at the (retreating) glacier front.…”

Glacial lake outburst flood risk in Himachal Pradesh, India: an integrative and anticipatory approach considering current and future threats

“…For moraine-dammed lakes, further parameters that may be integrated within a more complete large-scale assessment of dam stability and current GLOF hazard include dam geometry and freeboard height (Huggel et al 2004), the steepness of the lake front area (Fujita et al 2013), growth of the lake and associated glacier retreat (Bolch et al 2008), vegetation coverage in the dam area (Allen et al 2009), and permafrost conditions (Bolch et al 2011). However, some of these factors become highly uncertain, or, for dam characteristics, impossible to establish for the modelled future lakes.…”

Spatial patterns in glacier characteristics and area changes from 1962 to 2006 in the Kanchenjunga–Sikkim area, eastern Himalaya

“…In the last decades, the availability of low-cost data from optical remote sensing platforms with global coverage provided opportunities for glacier mapping at regional scales. Remote sensing techniques have considerably helped improve estimates of glacier area changes (Bhambri et al, 2010;Bolch, 2007;Bajracharya et al, 2007;Kamp et al, 2011;Bolch et al, 2008a), glacier lake changes (Bajracharya et al, 2007;Bolch et al, 2008b;Gardelle et al, 2011;Wessels et al, 2002) and region-wide glacier mass balance Bolch et al, 2011;Gardelle et al, 2013;Kääb et al, 2012), but significant gaps do remain. The new global Randolph Glacier Inventory (RGI) v.4 (Pfeffer et al, 2014) provides a global data set of glacier outlines intended for largescale studies; however, in some regions the quality varies and the outlines may not be suitable for detailed regional analysis of glacier parameters.…”