A. Linsbauer1, F. Paul1, M. Hoelzle2, H. Frey1, W. Haeberli1
1 Glaciology, Geomorphodynamics and Geochronology
Department of Geography, University of Zurich
CH-8057 Zurich, Switzerland
Telephone: +41 44 635 51 57
Fax: +41-44-635 68 41
2 Department of Geosciences, University of Fribourg
Chemin du Musée 4
CH-1700 Fribourg, Switzerland
Due to the ongoing and expected future increase in global mean temperature, the Alpine environment will continue to depart from equilibrium (Watson and Haeberli 2004). As glaciers form a significant part of the mountain cryosphere and their changes are considered to be the best natural indicators of climatic change (IPCC 2007), they constitute a key indicator within global climate related observing programs (Haeberli 2004). The already observed as well as the expected changes in glacier geometry and volume could have large impacts on global (sea level rise), regional (water supplies) and local scales (natural hazards, hydropower). The calculation and visualization of future glacier development thus plays a vital role in communicating climate change effects to a wider public (Paul et al. 2007).
Of particular interest regarding hydrological aspects is the water volume that is stored in the glaciers (Jansson et al. 2002). This requires information on the glacier bed which is only accessible after the glacier has disappeared (e.g. Maisch and Haeberli 1982). Otherwise, glacier thickness has to be obtained in the field at discrete points or profiles using a range of techniques (e.g. GPR, seismic or drilling). The spatial extraand interpolation of this local thickness information for reconstruction of the entire glacier bed is again based on a wide range of methods and assumptions with related uncertainties, but at least mean glacier thickness values can be derived. In order to overcome the scarcity of available measurements, a set of empirical (e.g. Chen and Ohmura 1990, Maisch and Haeberli 1982) or more physically based (Driedger and Kennard 1986, Haeberli and Hoelzle 1995) relationships have been proposed to obtain glacier volume for large samples of glaciers.
Apart from the amount of available water stored in glaciers, there is also an urgent need to have topographic information on the glacier bed itself. Anticipation and quantitative modelling of changes in surface topography and characteristics in large regions related to future climate change, and corresponding developments (landscape evolution, water cycle modifications, natural hazard potentials, tourism, hydropower, etc.) in cold mountain regions has become an important task. In this respect, an estimated topography of the glacier bed would facilitate a large number of applications including the visualization of future ice-free ground. Using examples from the Swiss Alps, this contribution presents a fast and robust GIS-based approach to construct digital elevation models (DEMs) “without glaciers” in currently glacierized mountain chains from a minimum set of input data (DEM, glacier outlines and flowlines).
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