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| Titel |
Future water yield from melting mountain permafrost: A fully distributed modelling approach |
| VerfasserIn |
Matthias Huss, Martin Scherler, Sina Schneider, Martin Hoelzle, Christian Hauck |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055793
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| Zusammenfassung |
| With climate change the question about water supply security in dry alpine regions arises.
Currently, melting glaciers release important volumes of water counteracting droughts in
regions with high water stress in the summer months. Significant water reservoirs in frozen
ground could potentially moderate low-flow conditions in alpine rivers when the glaciers
have completely disappeared. The modelling of the future water yield from permafrost
involves a variety of complex problems: (1) soil properties, such as porosity and ice content,
must be estimated in a spatially distributed way, and (2) the transient simulation of permafrost
melting in a hydrological catchment requires a model including all processes of ground mass
and heat transfer.
We present first results of studying the future permafrost evolution in the Murtèl-Corvatsch
region, South-eastern Swiss Alps, and the concurrent changes in catchment hydrology. The
drainage basin analyzed has a size of 5 km2, and covers different exposures and
surface types. The framework of the novel permafrost model presented here is the
glacio-hydrological model GERM that has been developed for calculating future runoff from
glacierized basins. The model simulates all cryospheric and hydrological variables (snow
accumulation distribution, snow and ice melt, 3D glacier geometry change, evaporation,
runoff routing) on a 25m-grid in daily resolution. Ground temperature profiles at
all grid cells are simulated using a minimum of readily available meteorological
input. The model is thus relatively fast and operationally applicable. Ground ice
content and subsurface properties are derived from in-situ measurements using
different geophysical methods, or are estimated from surface characteristics if no field
data are available. Ground temperature modelling is based on heat conduction and
includes processes of thawing and refreezing, as well as heat transfer by infiltrating
water, and thus allows calculating water yields due to changes in ice stored in frozen
soils.
Results of the distributed permafrost model are compared to the more complex COUP
model at one location and are validated against long-term ground temperature measurements
available in the Murtèl-Corvatsch region. The future water yield from mountain permafrost
simulated using realistic climate scenarios is expected to be relatively small, but could
nevertheless moderate extreme low-flow conditions in late summer. According to
first model results, permafrost contribution can account for up to 5% of August
runoff in dry years. However, uncertainties in this estimate are still considerable. |
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