Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 10 4 2006 10.5194/hess-10-495-2006 http://www.hydrol-earth-syst-sci.net/10/495/2006/ http://www.hydrol-earth-syst-sci.net/10/495/2006/hess-10-495-2006.html http://www.hydrol-earth-syst-sci.net/10/495/2006/hess-10-495-2006.pdf 495 506 2006-07-07 The dominant role of structure for solute transport in soil: experimental evidence and modelling of structure and transport in a field experiment H.-J. Vogel hjvogel@ufz.de I. Cousin O. Ippisch P. Bastian Institute of Environmental Physics, University of Heidelberg, Germany INRA, Unité de Science du Sol, Orléans, France Interdisciplinary Center of Scientific Computing, University of Heidelberg, Germany UFZ – Center for Environmental Research, Leipzig-Halle, Germany A classical transport experiment was performed in a field plot of 2.5 m² using the dye tracer brilliant blue. The measured tracer distribution demonstrates the dominant role of the heterogeneous soil structure for solute transport. As with many other published experiments, this evidences the need of considering the macroscopic structure of soil to predict flow and transport. We combine three different approaches to represent the relevant structure of the specific situation of our experiment: i) direct measurement, ii) statistical description of heterogeneities and iii) a conceptual model of structure formation. The structure of soil layers was directly obtained from serial sections in the field. The sub-scale heterogeneity within the soil horizons was modelled through correlated random fields with estimated correlation lengths and anisotropy. Earthworm burrows played a dominant role at the transition between the upper soil horizon and the subsoil. A model based on percolation theory is introduced that mimics the geometry of earthworm burrow systems. 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