Predictions in Ungauged Basins: Promise and Progress (Proceedings of symposium S7 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 303, 2006, 15-20.

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Identification of flow pathways along hillslopes using electrical resistivity tomography (ERT)

Stefan Uhlenbrook¹ & Jochen Wenninger²

1 UNESCO-IHE, Department of Water Engineering, PO Box 3015, 2601 DA Delft, The Netherlands

s.uhlenbrook@unesco-ihe.org

2 University of Freiburg, Institute of Hydrology, Fahnenbergplatz, D-79098 Freiburg, Germany

Abstract Hillslope processes are crucial as they define how fast water reaches the stream, how long water is stored in soil and groundwater systems, and which hydrochemical composition the water has when reaching the stream. In this paper the potential of electrical resistivity tomography (ERT) to identify flow pathways at the hillslope scale is demonstrated. This technique was used at two hillslopes (drained by a spring at the bottom) in addition to previously applied tracer methods that enabled the quantification of the runoff components during flood events. The structure of the soil and drift cover could be mapped using ERT and, consequently, the source areas of shallow and deep groundwater could be identified. Thus, the potential of a multi-technical approach (hydrometry, tracers and geophysics) is clearly demonstrated.

Key words Black Forest Mountains; electrical resistivity tomography (ERT); flow pathways; runoff generation

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