Response of flow systems in soils to extreme atmosperical boundary conditions

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Moisture and flow patterns are of utmost importance for matter transport and spatial distribution of nutrients and pollutants in the soil compartment of ecosystems. Soil structure, spatial variation of nonlinear material functions, and dynamics of upper boundary conditions are key factors of flow path formation. In forest soils, organic O - horizons, wettability and stones seem to play a prominent role in controlling infiltration patterns and preferential flow formation. The impact of extreme atmospheric boundary conditions on flow pattern generation, associated soil chemical effects and a possible change of flow systems make up the focus of the proposed research. Experiments are conducted at the laboratory, profile and plot scale. In the context of the central field manipulation experiments changes in dynamics and patterns of soil moisture and water repellency are investigated using time series analysis, geostatistics and analysis of variance. In addition associated physical and chemical parameters are determined. The deterministic process model WHNWIN is used for flux quantification of field plots and model aided interpretation of the manipulation experiments. The role of organic O- horizons and water repellency for preferential flow formation is studied in field tracer experiments by image analysis and VIS-NIR spectroscopy. Field studies are complemented by computer controlled column and batch experiments in the laboratory. Inverse modelling is applied for parameter and process identification.