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Relating stable isotope and geochemical data to conclude on water residence times in four small alpine headwater catchments with differing vegetation cover

Mueller, Matthias Heidulf and Weingartner, Rolf and Alewell, Christine. (2012) Relating stable isotope and geochemical data to conclude on water residence times in four small alpine headwater catchments with differing vegetation cover. In: Hydrology and Earth System Sciences Discussions (HESSD), 9. Niagara Falls, Canada, pp. 11005-11048.

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Official URL: http://edoc.unibas.ch/42039/

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Abstract

The mean water residence time (MRT) in a catchment gives information about storage,flow pathways, sources of water and thus also about retention and release of solutes in a catchment. To our knowledge there are no catchment studies on the influence of 5 vegetation cover change on base flow mean water residence times. The main changes in vegetation cover in the Swiss Alps are massive shrub encroachment and forest expansion into formerly open habitats. Four small and relatively steep catchments in the Swiss Alps (Ursern valley) were investigated to relate different vegetation cover to water residence times and geochemical behaviour of runoff. 10 Time series of water stable isotopes were used to calculate mean water residence times. The high temporal variation of the stable isotope signals in precipitation was strongly dampened in stream base flow samples. Mean water residence times of the four catchments were 64–98 weeks. The strong dampening of our input signal might point to deeper flow paths and mixing of waters of different ages at the catchments out15 lets. Parent geological materials are mainly gneisses and schists but they can contain dolomite, carbonate or gypsum rich zones. The major part of the quickly infiltrating precipitation likely percolates through these deeper zones. Relatively high stream water pH, Ca and SO2−4 concentrations in micro catchment outlets support this conclusion. We conclude that in mountainous headwater catchments with relatively thin soil lay20 ers the geological and topographical situation and snow dynamics influence storage,mixing and release of meteoric waters and its geochemistry in a stronger way than vegetation cover or catchment size do.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Umweltgeowissenschaften (Alewell)
UniBasel Contributors:Müller, Matthias Heidulf and Alewell, Christine
Item Type:Conference or Workshop Item
Conference or workshop item Subtype:Conference Paper
Publisher:European Geosciences Union
Note:Publication type according to Uni Basel Research Database: Conference paper
Identification Number:
Last Modified:10 Feb 2021 15:02
Deposited On:10 Jun 2020 14:17

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