Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 3 2009 10.5194/hess-13-285-2009 http://www.hydrol-earth-syst-sci.net/13/285/2009/ http://www.hydrol-earth-syst-sci.net/13/285/2009/hess-13-285-2009.html http://www.hydrol-earth-syst-sci.net/13/285/2009/hess-13-285-2009.pdf 285 292 2009-03-02 Mixing and transport of water in a karst catchment: a case study from precipitation via seepage to the spring K. Schwarz J. A. C. Barth barth@geol.uni-erlangen.de C. Postigo-Rebollo P. Grathwohl Eberhard Karls University of Tübingen, Center for Applied Geoscience, Sigwartstr. 10, 72076 Tübingen, Germany Lehrstuhl für Angewandte Geologie, GeoZentrum Nordbayern der Friedrich-Alexander-Universität Erlangen-Nürnberg, Schloßgarten 5, 91054 Erlangen, Germany Consejo Superior de Investigaciones Científicas, Jordi Girona 18–26, 08034 Barcelona, Spain One of the best-known and largest karst areas in Germany, the Blautopf Catchment, offers unique access to waters of the unsaturated zone through a large cave system. It was investigated with stable isotopes (¹⁸O/¹⁶O and D/H ratios expressed in permille = ‰) in precipitation, seepage- and groundwater as tracers for water flow, mixing, and storage. The precipitation showed a distinct seasonality with δ¹⁸O values between −2.9 and −24.6‰ during summer and winter, respectively. 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