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UP: Umweltphysik
UP 2: Hydrosph
äre
UP 2.5: Fachvortrag
Monday, March 13, 2006, 17:30–17:45, A
Contributions from environmental tracers to build up a conceptual flow and transport-model of a contaminated aquifer system — •R. Althaus1, S. Klump2, G. A. Onnis3, R. Kipfer2, R. Purtschert1, F. Stauffer3, and W. Kinzelbach3 — 1Climate and Environmental Physics Division, Phys. Institute, Univ. Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland — 2Water Resources and Drinking Water, EAWAG, CH-8600 Dübendorf, Switzerland — 3Institute of Hydromechanics and Water Resources Management, ETH-Zürich, CH-8093 Zürich, Switzerland
A large set of environmental tracer methods (3H/3He, 85Kr, SF6, CFC’s, 4Herad, NGT’s, δ 18O, δ 2H) was used to build up and constrain a flow model for a heterogeneous aquifer system of a town in Switzerland. Knowledge about the flow dynamics of the groundwater is the basis for the construction of a numerical flow and transport model which allows conclusions about the future behaviour of the contaminants. Estimated groundwater residence time increase from one year near the recharge areas in the North of the town to over 50 years in the river plane in the South. Additionally an age stratification with depth could be observed. Despite of the hydrogeological heterogeneities and non atmospheric subsurface tritium sources, 85Kr and 3H/3He Piston flow ages correspond very well. Depleted noble gas temperatures and the isotopic composition of water suggest that a significant amount of water recharged at higher elevations with a lower mean annual temperature is present in parts of the aquifer. It is assumed that this water is related to the karstic system of the nearby mountains.