Abstract
Abstract. Global warming is expected to significantly affect the runoff regime of mountainous catchments. Simple methods for calculating future glacier change in hydrological models are required in order to reliably assess economic impacts of changes in the water cycle over the next decades. Models for temporal and spatial glacier evolution need to describe the climate forcing acting on the glacier, and ice flow dynamics. Flow models, however, demand considerable computational resources and field data input and are moreover not applicable on the regional scale. Here, we propose a simple parameterization for calculating the change in glacier surface elevation and area, which is mass conserving and suited for hydrological modelling. The Δh-parameterization is an empirical glacier-specific function derived from observations in the past that can easily be applied to large samples of glaciers. We compare the Δh-parameterization to results of a 3-D finite-element ice flow model. As case studies, the evolution of two Alpine glaciers of different size over the period 2008–2100 is investigated using regional climate scenarios. The parameterization closely reproduces the distributed ice thickness change, as well as glacier area and length predicted by the ice flow model. This indicates that for the purpose of transient runoff forecasts, future glacier geometry change can be approximated using a simple parameterization instead of complex ice flow modelling. Furthermore, we analyse alpine glacier response to 21st century climate change and consequent shifts in the runoff regime of a highly glacierized catchment using the proposed methods.
Highlights
The retreat of mountain glaciers in response to ongoing climate change is expected to have major impacts on the water resources in alpine environments all over the world (e.g., Zierl and Bugmann, 2005; Horton et al, 2006; Hagg et al, 2006; Bradley, 2006; Stahl et al, 2008)
In order to investigate the suitability of alternatFivige. s1i4m. pCleomapp-arisonFoifgs. i1m4p. lCe oamltepranraitsiovne oafppsirmoapclheeasltfeorrnacatilvceulaaptipnrgoafcuhtuersefogrlaccaielcruclahta-nge with the i proaches response to to calculate the change in glacier smurofdaecle. future climate change we compare twoeGalaicnier suppleing future glacier change with the ice areaan, dan(bd )(ble)nlgetnhgt(hRh(Rohnoegnleegtlsecthsecrh)e.r)
Our results show that the h-parameterization reproduces results given by the application of a complex ice flow model, and that the parameterization is suitable for the calculation of glacier retreat in response to future climate change
Summary
The retreat of mountain glaciers in response to ongoing climate change is expected to have major impacts on the water resources in alpine environments all over the world (e.g., Zierl and Bugmann, 2005; Horton et al, 2006; Hagg et al, 2006; Bradley, 2006; Stahl et al, 2008). Storage of fresh water in the seasonal snow cover and glacier ice is a key element in the water cycle on different temporal and spatial scales. It importantly affects issues of irrigation and hydropower production in mountainous regions and adjacent lowlands. The assessment of glacier geometry change requires the description of (1) the surface mass balance reflecting the climatic forcing, and (2) the ice flow dynamics
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