Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 22 4th EGU Alexander von Humboldt Conference "The Andes: Challenge for Geosciences" 2009 10.5194/adgeo-22-51-2009 http://www.adv-geosci.net/22/51/2009/ http://www.adv-geosci.net/22/51/2009/adgeo-22-51-2009.html http://www.adv-geosci.net/22/51/2009/adgeo-22-51-2009.pdf 51 57 2009-10-13 Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile G. Strauch gerhard.strauch@ufz.de R. Oyarzún F. Reinstorf J. Oyarzún M. Schirmer K. Knöller Helmholtz Centre for Environmental Research UFZ, Department Hydrogeology, Permoserstrasse 15, 04318 Leipzig, Germany Departamento Ingeniería de Minas, Universidad de La Serena, Casilla 554, La Serena, Chile Centro de Estudios Avanzados en Zonas Aridas (CEAZA), Benavente 980, La Serena, Chile Technical University Magdeburg-Stendal, Department Water Management, Breitscheidstraße 2, 39114 Magdeburg, Germany EAWAG – Swiss Federal Institute of Aquatic Science and Technology, Department Water Resources and Drinking Water, Dübendorf, Switzerland Helmholtz Centre for Environmental Research UFZ, Department Isotope Hydrology, Theodor-Lieser-Str. 4, 06120 Halle (Saale), Germany For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain/snow precipitation, surface/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i) the origin of water, (ii) water quality, (iii) relations of surface and groundwater. <br><br> Applying the complex multi-isotopic and hydrochemical methodology to the water components of the Huasco and Limarí basins, a differentiation of water components concerning subsurface flow and river water along the catchment area and by anthropogenic impacts are detected. Sulphate and nitrate concentrations indicate remarkable input from mining and agricultural activities along the river catchment. <br><br> The ²H-¹⁸O relations of river water and groundwater of both catchments point to the behaviour of river waters originated in an arid to semi-arid environment. <br><br> Consequently, the groundwater from several production wells in the lower parts of the catchments is related to the rivers where the wells located, however, it can be distinguished from the river water. Using the hydrological water balance and the isotope mixing model, the interaction between surface and subsurface flows and river flow is estimated. % vor jede Referenz Bissig, T., Clark, A. H., Lee, J. K. W., and Hodgson, C. J.: Miocene landscape evolution and geomorphologic controls on epithermal processes in El Indio-Pascua Au-Ag-Cu belt, Chile and Argentina, Econ. Geol. 7, 971–996, 2002. 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