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| Titel |
Future high-mountain hydrology: a new parameterization of glacier retreat |
| VerfasserIn |
Matthias Huss, Guillaume Jouvet, Daniel Farinotti |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250034141
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| Zusammenfassung |
| Climate 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 efficiently project economic impacts of changes in the water cycle in
alpine regions 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 computation power and field data input. Moreover, they are
not applicable on the regional scale.
We propose a simple parameterization – termed Îh-parameterization – for calculating the
change in glacier surface elevation and area. The parameterization is mass conserving and
thus suited for long-term hydrological modelling. The Îh-parameterization is an empirical
glacier-specific function that is derived from observations in the past. It can easily be applied
to large samples of glaciers and therefore be used for regional scale hydrological projections
for alpine catchments over the 21st century.
We compare the results of the Îh-parameterization against a 3D finite-element ice flow
model. In case studies the evolution of two Alpine glaciers of different size over
the period 2008-2100 is investigated using different 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 this simple parameterization instead of complex ice flow
modelling.
According to our model the two analyzed glaciers show dramatic retreat over the 21st
century in response to climate warming. Silvrettagletscher, a small mountain glacier, is
expected to disappear around 2070. Rhonegletscher, a medium-sized valley glacier, might
still be present by 2100, however, strongly reduced in size. We analyse the consequent shifts
in the runoff regime of the highly glacierized catchment of Rhonegletscher using the
proposed methods. Fast release of water from long-term glacial storage leads to a significant
increase in runoff over the next decades. For 2040 calculated annual runoff is between 23%
and 36% higher than in 1961-1990, depending on the scenario. We find strong changes in the
hydrological regime; after an initial surge from intense ice melt, low-flow conditions
will prevail in the summer months over the second half of the 21st century. Peak
runoff will be shifted and is expected to occur two months earlier in the season. |
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