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| Titel |
Effects of climate and irrigation changes on the water balance of a Mediterranean catchment |
| VerfasserIn |
Diane von Gunten, Thomas Wöhling, Claus Haslauer, Olaf Cirpka |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250103883
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| Publikation (Nr.) |
 EGU/EGU2015-3304.pdf |
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| Zusammenfassung |
| Climate change will strongly impact the water cycle of Mediterranean catchments as a result
of the changes in precipitation patterns and increased temperature. However, effects of
climate change are difficult to predict with precision and are often influenced by land-use or
water management choices. In agricultural catchments, irrigation is of particular
interest because of its importance for cultivation in semi-arid climate and because of
its strong impacts on hydrological processes. Interactions between irrigation and
climate change impacts are likely to be important and should be considered when
studying the future of a catchment. However, they are still difficult to quantify. A better
understanding of the differences in climate-change sensitivity between irrigated and
non-irrigated catchments would allow a finer description of local climate change
effects.
In this study, we compared the impacts of climate change in various irrigation scenarios,
including a scenario without irrigation. Our case study was a relatively small catchment
(about 7.5km2) in north-east Spain, called the Lerma catchment. This catchment
was not irrigated prior to 2006, but 54% of its surface is now used for irrigated
agriculture. This transition to irrigated agriculture was closely monitored and data on
hydraulic heads, discharge and daily irrigation volume are available. Based on these
measurements, a coupled surface-subsurface model of the catchment was developed
using the pde-based model HydroGeoSphere. The model performs well for both
irrigated and non-irrigated periods. Future climate was predicted using four regional
climate models from the ENSEMBLE project (P.van der Linden and J.Mitchell,
ENSEMBLES: Climate Change and its Impacts [...], Met Office Hadley Center, 2009)
and two downscaling methods, including one based on a weather generator. Four
irrigation scenarios, based on projected potential evapotranspiration changes, were
compared.
Our results show a shift in the climate sensitivity of the catchment as a result of the
irrigation changes. In the scenarios with irrigation, low flow and hydraulic heads were more
sensitive to climate change, probably because of the increased connectivity between
surface and subsurface, resulting from the higher water table. Hydraulics heads
decreases of about 0.7m with the present irrigation, but of only about 0.1m in the
scenarios without irrigation. On the contrary, peak flow increased more in scenarios
without irrigation. In summer, actual evapotranspiration showed an increase of
about 10% with future irrigation, but a decrease of about 5% without irrigation. |
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