Glacial lakes of the Hinku and Hongu valleys, Makalu Barun National Park and Buffer Zone, Nepal

An assessment of conditions before and after the 1998 Tam Pokhari outburst in the Nepal Himalaya and an evaluation of the future outburst hazard

“…From the elevation difference between the pre‐GLOF lake surface mark and the present lake surface (both measured in the field), Byers et al () estimated that the lake's pre‐GLOF level was 60 m higher than the present level. Dwivedi et al () and Osti and Egashira () report the water level change as 52 m and 50 m, respectively (Table ).…”

“…Integration of ground surveys and remote sensing analyses are essential for identification of the outburst potential of glacial lakes (Byers et al , ). Despite the existence of lists of potentially dangerous glacial lakes in the Nepal Himalaya (Mool et al , ; Bajracharya et al , ; ICIMOD, ), there is still a lack of adequate field‐based surveys and field verification of data produced by remotely sensing methods.…”

“…In fact, a small avalanche did cascade into the lake, producing small surge waves, during our field visit in 2009. Byers et al () also reported, as described by lodge owners and other local people, that the lake occasionally experiences minor surge floods of varying size. Therefore, the likelihood of additional surge waves that may threaten the Taknak community cannot be totally ruled out, especially given the community's recent development into the flood zone (Figure ) as well as the prevalence of earthquakes in the region (Osti et al , ).…”

“…In contrast, a lake with a wide terminal dam and a gentler slope can withstand the pressure generated by lake water and displacement waves, and may not drain even if triggering events occur. Moreover, the presence of a broad terminal moraine will help to moderate surge waves from the lake, thus serving as a neutralizing buffer (Byers et al , ). Prior to the 1998 GLOF, the lake had a very high (120 ± 5 m) and narrow (75 ± 6 m) moraine dam (width to height ratio = ~0.6), and therefore, it was more susceptible to the impact of displacement waves.…”

Modeling a glacial lake outburst flood process chain: the case of Lake Palcacocha and Huaraz, Peru

“…Calculating downstream inundation caused by a GLOF event requires the simulation of debris flow propagation, since sediment entrainment can cause the volume and peak discharge to increase by as much as 3 times (Worni et al, 2014;Osti and Egashira, 2009). One-dimensional models based on the St. Venant equations have been used to model the downstream flood wave propagation of a GLOF, e.g., Klimes et al (2013), who used HEC-RAS (USACE, 2010) to reproduce the 2010 GLOF from Lake 513 in Peru, Cenderelli and Wohl (2003), who used HEC-RAS to reproduce steady-state aspects of GLOFs in the Khumbu region of Nepal, Byers et al (2013), who used HEC-RAS to model a potential GLOF from Lake 464 in the Hongu valley of Nepal, Meon and Schwarz (1993), who used DAMBRK (Fread, 1988) to model a potential GLOF in the Arun valley of Nepal, and Bajracharya et al (2007), who used FLDWAV (NWS, 1998 to model a potential GLOF from Imja Lake in Nepal. Two-dimensional SWE models are often used to model downstream impacts of GLOFs, e.g., Worni et al (2012), who used BASEMENT to model flooding from a GLOF at Shako Cho Lake in India, Schneider et al (2014), who used RAMMS to model debris flow from an overtopping wave at Lake 513 in Peru, Somos-Valenzuela et al (2015), who used FLO2D to model downstream inundation from a potential GLOF at Imja Lake in Nepal, and Mergili et al (2011), who used RAMMS and FLO2D to simulate flooding from Lake Khavraz in Tajikistan.…”