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| Titel |
Climate change impacts on the hydrology of a small lowland catchment and the leaching of a heavy metal contamination |
| VerfasserIn |
Ate Visser, Joop Kroes, Michelle van Vliet, Stephen Blenkinsop, Hans Peter Broers |
| 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 |
250047118
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| Zusammenfassung |
| The objective of this study was to assess the potential effects of climate change on the
hydrology of the small partially-irrigated agricultural lowland catchment of the Keersop, in
south of the Netherlands, as well as the transport of a pre-existing spatially extensive trace
metal contamination. The area surrounding the Keersop has been contaminated with heavy
metals by the atmospheric emissions of four zinc ore smelters. This heavy metal
contamination, with Cd and Zn for example, has accumulated in the topsoil and leaches
towards the surface water system, especially during periods with high groundwater levels and
high discharge rates.
Daily time-series of precipitation and potential evapotranspiration were derived from the
results of eight regional climate model experiments under the SRES A2 emissions scenario.
They each span 100 years and are representative for the periods 1961-1990 (“baseline
climate”) and 2071-2100 (“future climate”). The time-series of future climate were
characterized by lower precipitation (-1% to -12%) and higher air temperatures (between
2Ë C and 5Ë C), and as a result higher potential evapotranspiration, especially in
summer. The time-series were used to drive the quasi-2D unsaturated-saturated zone
model (SWAP) of the Keersop catchment (43 km2). The model consisted of an
ensemble of 686 1D models, each of which represented a 250x250 m area within the
catchment.
Simulation results for the future climate scenarios show a shift in the water balance of the
catchment. The decrease in annual rainfall is nearly compensated by an increase in irrigation
in the catchment, if present day irrigation rules are followed. On the other hand, both
evaporation and transpiration fluxes increase. This increase is compensated by a decrease in
the drainage flux and groundwater recharge. As a result, groundwater levels decline and the
annual discharge of the Keersop stream decreases under all future climate scenarios, by 26%
to 46%.
Because Cd and Zn have accumulated in the top soil, the concentrations in the Keersop
stream under present day climate react to groundwater level fluctuations. As a result of lower
groundwater levels under future climate scenarios, the transport of Cd and Zn towards surface
water is projected to decrease. The mass balance of Cd and Zn for the catchment changes
towards more storage (adsorption to the soil) and less leaching. Overall, the soils in the
catchment function as a sink for Cd and Zn, both under baseline and future climate
conditions.
In conclusion, climate change leads to an intensification of the soil-plant-atmosphere
coupling and a slowing-down of the groundwater system. This results in a positive impact on
a limited aspect of surface water quality. To provide useful advice to water managers on the
impact of future climate on water quality, all aspects of water quality should be considered. |
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