Abstract
Abstract. A case study of glacial lakes outburst flood (GLOF) hazard assessment by satellite Earth observation (EO) and numerical modelling is presented for the supraglacial and ice-contact lakes on Thangothang Chhu glacier, Chomolhari area (Bhutan). Detailed geomorphological mapping, including landslide and rock glacier inventories, as well as surface displacement determination using an interferometric SAR (InSAR) satellite, allowed a GLOF hazard assessment for lake Wa-007 to be performed. Outburst scenario modelling was achieved by combining both empirical and numerical modelling approaches, revealing that only a flood wave can have an impact on the two human settlements located downslope of Wa-007 lake. The worst-case scenario, modelled thanks to r.damflood, allowed the wave-front arrival time, the maximum water depth and the arrival time of maximum water height for the two human settlements to be quantified. A long-term monitoring strategy based entirely on EO data, with an update cycle of 5 years, is proposed to assess the future evolution of the area.
Highlights
Thanks to satellite Earth observation (EO), hazard assessments of glacial lake outburst floods (GLOFs) were performed in several mountain chains of the world, including the Alps (e.g. Haeberli, 1983; Huggel et al, 2004; Haeberli et al, 2001), the Andes (e.g. Schneider et al, 2014; Schaub et al, 2015; Frey et al, 2016) and the Himalayas (e.g. Budhathoki et al, 2010; Haemmig et al, 2014) in the last years
The GLOF hazard assessment is to be considered to be a part of the general topic concerning the connection between high-mountain hazards and climate change (e.g. GAPHAZ, 2017), which integrates the impact of permafrost degradation on the stability of rock slopes above glaciers (e.g. Gruber and Haeberli, 2007; Krautblatter et al, 2013) or the increasing hazard related to ice-rock avalanches falling into new lakes from icy peaks with degrading permafrost (e.g. Salzmann et al, 2004; Haeberli et al, 2017)
This paper presents a GLOF hazard assessment for the supraglacial lake Wa-007 on the Thangothang Chhu glacier, Chomolhari area in the Bhutan Himalayas
Summary
Thanks to satellite Earth observation (EO), hazard assessments of glacial lake outburst floods (GLOFs) were performed in several mountain chains of the world, including the Alps (e.g. Haeberli, 1983; Huggel et al, 2004; Haeberli et al, 2001), the Andes (e.g. Schneider et al, 2014; Schaub et al, 2015; Frey et al, 2016) and the Himalayas (e.g. Budhathoki et al, 2010; Haemmig et al, 2014) in the last years. This paper presents a GLOF hazard assessment for the supraglacial lake Wa-007 on the Thangothang Chhu glacier, Chomolhari area in the Bhutan Himalayas This assessment was carried out in the framework of a European Space Agency–World Bank (ESA–WB) collaboration project on satellite EO in the Himalayas, where landslides, floods and GLOF hazard assessments were performed in Nepal and Bhutan (Sauerbier et al, 2015a; Scapozza, 2015; Ambrosi et al, 2018). Within this framework, the GLOF hazard assessment has made it possible to combine observations from flood and landslide hazard mapping, as well as to valorise the products derived from land use and land cover mapping and from the generation of high-resolution digital-elevation models (DEMs)
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