NEW LAKES IN DE-GLACIATING HIGH-MOUNTAIN REGIONS – A CHALLENGE FOR INTEGRATIVE RESEARCH ABOUT RISK REDUCTION AND SUSTAINABLE USE Wilfried Haeberli, Christian Huggel, Yvonne Schaub, Geography Department University of Zurich Foro Intercaional Glaciares
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NEW LAKES IN DE-GLACIATING HIGH-MOUNTAIN REGIONS – A CHALLENGE FOR INTEGRATIVE RESEARCH ABOUT RISK REDUCTION AND SUSTAINABLE USE
Wilfried Haeberli, Christian Huggel, Yvonne Schaub, Geography Department University of Zurich
Foro Intercaional Glaciares
vanishing surface ice
de-buttressing of lateral rock slopes oversteepened
inside slope of lateral moraine
disappearing support of steep glacier parts, ice avalanches from steep hanging glaciers
ice avalanches and rock falls not on glacier tongue any more but directly into lake
permafrost degradation slope instability
Milhuacocha Cordillera Blanca Hegglin
lake formation
Foro Intercaional Glaciares
Changing high-mountain glaciers
Paul
Cordillera Blanca
Aletsch, Alps
Assumption: temperature increase of 4°C by 2100, time steps of 15 years
Scenario of glacier retreat and lake formation Swiss Alps (Aletsch)
Aletsch Swiss Alps Schaub
Glaciers, new lakes, permafrost and steep slopes in the Alps
Foro Intercaional Glaciares
Portocarrero 12.04.2010
A successfully prevented catastrophe
Nevado Hualcán Cordillera Blanca Portocarrero
Foro Intercaional Glaciares
Palcacocha, Peru
Modeling the process chain and installation of an early warning system …
Nevado Hualcán Cordillera Blanca Schneider
Foro Intercaional Glaciares
Lake probably shallow
Lake probably deep
Lake formation uncertain
Lake formation ongoing or imminent
Lake formation in coming decades
possible retention
Hazard evolution Carhuaz
Terrier
Terrier
Künzler
Hydropower and flood protection Corbassiière Swiss Alps
Foro Intercaional Glaciares
The long-term risks of destructive flood waves from new lakes in deglaciating high-mountain regions are increasing …
… and need risk reduction strategies to be developed in time
because • the number of new lakes increases with continued glacier retreat • the new lakes are forming more and more closely to steep icy rock walls • the stability of these steep icy rock walls tends to decrease • the probability of large ice/rock avalanches into lakes increases • impact waves in new lakes from slope instability become more frequent • corresponding flood waves can affect valleys over long distances • the hazard zone related to rock/ice avalanches is thereby extended • areas of high vulnerability/damage potential may be affected • the probability of dangerous events and the damage potential both grow
by • modelling potential new lakes and critical slope conditions • modelling potential process chains to delineate hazard zones • defining hot spots of highest vulnerability • using existing experience/practice of protection against impact waves • considering aspects of long-term low probability/high damage risks • envisaging possible synergies with hydropower, water supply, tourism