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Glaciers and Glacial Lake Outburst Flood Risk Modeling For Flood Management
Published in Ajai Singh, Wastewater Reuse and Watershed Management, 2019
Nity Tirkey, P. K. Parhi, A. K. Lohani
In the Himalayas, during the retreating phase, a large number of lakes are being formed either at the snout of the glacier as a result of damming of the moronic material known as moraine-dammed lakes or supraglacial lakes formed in the glacier surface area. Most of these lakes are formed by the accumulation of vast amounts of water from the melting of snow and by blockade of end moraines located in the down valleys close to the glaciers. In addition, the lakes can also be formed due to landslides causing artificial blocks in the waterways. The sudden break of a moraine/block may generate the discharge of large volumes of water and debris from these glacial lakes and water bodies causing flash floods namely GLOF. The sudden bursts of lakes can happen due to erosion, a buildup of water pressure, an avalanche of rock or heavy snow, an earthquake, or if a large enough portion of a glacier breaks off and massively displaces the waters in a glacial lake at its base (Figure 13.2).
Genesis of hummocks found in tunnel valleys: an example from Hörda, southern Sweden
Published in GFF, 2018
Gustaf Peterson, Mark D. Johnson, Sandra Dahlgren, Tore Påsse, Helena Alexanderson
Meltwater production from glaciers is expected to increase as a result of a warming climate (Tedesco et al. 2012). Moreover, sudden drainage of subglacial and supraglacial lakes at the Greenland and Antarctic ice sheets of up to billions of cubic meters of water creates a highly dynamic glacial hydrological system (Stearns et al. 2008; Dow et al. 2015; Palmer et al. 2015; Willis et al. 2015). The evolution of the hydrologic systems in former ice sheets during periods with increased amounts of meltwater is still a field about which little is known (Greenwood et al. 2016). However, geomorphologic mapping and sedimentological studies of imprints and deposits from the subglacial hydrological system of formerly glaciated regions have the capacity to deepen our understanding of ice-sheet response to increased meltwater production.
Glacial lake changes and outburst flood hazard in Chandra basin, North-Western Indian Himalaya
Published in Geomatics, Natural Hazards and Risk, 2018
Ice-dammed lakes or supraglacial lakes represent the initial phase of glacial lake evolution (Quincey et al. 2007; Sakai 2012) and are more dynamic in nature due to a strong influence of climatic factors (e.g. temperature, precipitation, etc.,) and non-climatic factors (e.g. debris cover, glacier surface slope, speed of glacier and condition of glacier)(Wang et al. 2016). The size, shape, and locations of such lakes change rapidly as these are unstable and temporary which may survive from a few months to several years (Wang et al. 2012). Such lakes accelerate the ablation of glacier ice by draining water through hydro-fracture/cracks to subglacial channels accelerating the melting and disintegration of ice at glacier bottom (Watanabe et al. 1995; Reynolds 2000; Benn et al. 2001). The change in ice-dammed lakes in the Chandra basin shows characteristics of disappearance and formation of new lakes simultaneously. Overall there is an increase in the number and area of ice-dammed lakes from 2000 to 2014. Highest changes in ice-dammed lakes are on Bara Shigri glacier in the basin, largest glacier in the basin (28 km long, 3 km wide with 131 km2 area). The thick debris cover and relatively flat slope of <40 of Bara Shigri glacier represent the most conducive features for the formation of supraglacial lakes. About 60 lakes of size >500 m2 were detected by Schauwecker et al. (2015) in 2014 using high-resolution SPOT images, which is in accordance with the observation of present study (Figure 6).