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Increasing risks related to landslides from degrading permafrost into new lakes in de-glaciating mountain ranges


Haeberli, Wilfried; Schaub, Yvonne; Huggel, Christian (2017). Increasing risks related to landslides from degrading permafrost into new lakes in de-glaciating mountain ranges. Geomorphology, 293:405-417.

Abstract

While glacier volumes inmost coldmountain ranges rapidly decrease due to continued global warming, degradation of permafrost at altitudes above and below glaciers is much slower. As a consequence,many still existing glacier and permafrost landscapes probably transformwithin decades into new landscapes of bare bedrock, loose debris, sparse vegetation, numerous new lakes and steep slopes with slowly degrading permafrost. These new landscapes are likely to persist for centuries if not millennia to come. During variable but mostly extended future time periods, such new landscapes will be characterized by pronounced disequilibria within their geo- and ecosystems. This especially involves long-term stability reduction of steep/icy mountain slopes as a slow and delayed reaction to stress redistribution following de-buttressing by vanishing glaciers and to changes in mechanical strength and hydraulic permeability caused by permafrost degradation. Thereby, the probability of far-reaching floodwaves fromlargemassmovements into lakes systematically increases with the formation of many new lakes and systems of lakes in close neighborhood to, or even directly at the foot of, so-affected slopes. Results of recent studies in the Swiss Alps are reviewed and complemented with examples from the Cordillera Blanca in Peru and the Mount Everest region in Nepal. Hot spots of future hazards frompotential flood waves caused by large rock falls into new lakes can already now be recognized. To this end, integrated spatial information on glacier/permafrost evolution and lake formation can be used together with scenario-based models for rapid mass movements, impact waves and flood propagation. The resulting information must then be combined with exposure and vulnerability considerations related to settlements and infrastructure. This enables timely planning of risk reduction options. Such risk reduction options consist of two components: Mitigation of hazards, which in the present context are due to effects from climate change, and reduction in consequences, which result from societal conditions and changes. Hazard mitigation may include artificial lake drainage or lake-level lowering and flood retention, optimally in connection with multipurpose structures for hydropower production and/or irrigation. Reduction in damage potential (exposure, vulnerability) can be accomplished by installing early-warning systems, adapting spatial planning and/or by improving preparedness of local people and institutions.

Abstract

While glacier volumes inmost coldmountain ranges rapidly decrease due to continued global warming, degradation of permafrost at altitudes above and below glaciers is much slower. As a consequence,many still existing glacier and permafrost landscapes probably transformwithin decades into new landscapes of bare bedrock, loose debris, sparse vegetation, numerous new lakes and steep slopes with slowly degrading permafrost. These new landscapes are likely to persist for centuries if not millennia to come. During variable but mostly extended future time periods, such new landscapes will be characterized by pronounced disequilibria within their geo- and ecosystems. This especially involves long-term stability reduction of steep/icy mountain slopes as a slow and delayed reaction to stress redistribution following de-buttressing by vanishing glaciers and to changes in mechanical strength and hydraulic permeability caused by permafrost degradation. Thereby, the probability of far-reaching floodwaves fromlargemassmovements into lakes systematically increases with the formation of many new lakes and systems of lakes in close neighborhood to, or even directly at the foot of, so-affected slopes. Results of recent studies in the Swiss Alps are reviewed and complemented with examples from the Cordillera Blanca in Peru and the Mount Everest region in Nepal. Hot spots of future hazards frompotential flood waves caused by large rock falls into new lakes can already now be recognized. To this end, integrated spatial information on glacier/permafrost evolution and lake formation can be used together with scenario-based models for rapid mass movements, impact waves and flood propagation. The resulting information must then be combined with exposure and vulnerability considerations related to settlements and infrastructure. This enables timely planning of risk reduction options. Such risk reduction options consist of two components: Mitigation of hazards, which in the present context are due to effects from climate change, and reduction in consequences, which result from societal conditions and changes. Hazard mitigation may include artificial lake drainage or lake-level lowering and flood retention, optimally in connection with multipurpose structures for hydropower production and/or irrigation. Reduction in damage potential (exposure, vulnerability) can be accomplished by installing early-warning systems, adapting spatial planning and/or by improving preparedness of local people and institutions.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Language:English
Date:2017
Deposited On:15 Nov 2016 17:47
Last Modified:21 Nov 2017 18:41
Publisher:Elsevier
ISSN:0169-555X
Publisher DOI:https://doi.org/10.1016/j.geomorph.2016.02.009

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