TY - GEN A1 - Wienhöfer, Jan A1 - Germer, Kai A1 - Lindenmaier, Falk A1 - Färber, Arne A1 - Zehe, Erwin T1 - Applied tracers for the observation of subsurface stormflow at the hillslope scale N2 - Rain fall-runoff response in temperate humid headwater catchments is mainly controlled by hydrolo gical processes at the hillslope scale. Applied tracer experiments with fluore scent dye and salt tracers are well known tools in groundwater studies at the large scale and vadose zone studies at the plot scale, where they provide a means to characterise subsurface flow. We extend this approach to the hillslope scale to investigate saturated and unsaturated flow path s concertedly at a forested hill slope in the Austrian Alps. Dye staining experiments at the plot scale revealed that crack s and soil pipe s function as preferential flow path s in the fine-textured soils of the study area, and these preferenti al flow structures were active in fast subsurface transport of tracers at the hillslope scale. Breakthrough curves obtained under steady flow conditions could be fitted well to a one-dimensional convection-dispersion model. Under natural rain fall a positive correlation of tracer concentrations to the transient flows was observed. The results of this study demon strate qualitative and quantitative effects of preferential flow feature s on subsurface stormflow in a temperate humid headwater catchment. It turn s out that , at the hill slope scale, the interaction s of structures and processes are intrinsically complex, which implies that attempts to model such a hillslope satisfactorily require detailed investigation s of effective structures and parameters at the scale of interest. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 146 KW - Saturated hydraulic conductivity KW - preferential flow pathways KW - solute transport KW - runoff generation KW - fluorescent dyes Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45246 ER - TY - JOUR A1 - Scheffler, Raphael A1 - Neill, Christopher A1 - Krusche, Alex V. A1 - Elsenbeer, Helmut T1 - Soil hydraulic response to land-use change associated with the recent soybean expansion at the Amazon agricultural frontier JF - Agriculture, ecosystems & environment : an international journal for scientific research on the relationship of agriculture and food production to the biosphere N2 - Clearing for large-scale soy production and the displacement of cattle-breeding by soybeans are major features of land-use change in the lowland Amazon that can alter hydrologic properties of soils and the runoff generation over large areas. We measured infiltrability and saturated hydraulic conductivity (Ksat) under natural forest, pasture, and soybeans on Oxisols in a region of rapid soybean expansion in Mato Grosso, Brazil. The forest-pasture conversion reduced infiltrability from 1258 to 100 mm/h and Ksat at all depths. The pasture-soy conversion increased infiltrability from 100 to 469 mm/h (attributed to shallow disking), did not affect Ksat at 12.5 cm, but decreased Ksat at 30 cm from 122 to 80 mm/h, suggesting that soybean cultivation enhances subsoil compaction. Permeability decreased markedly with depth under forest, did not change under pasture, and averaged out at one fourth the forest value under soybeans with a similar pattern of anisotropy. Comparisons of permeability with rainfall intensities indicated that land-use change did not alter the predominantly vertical water movement within the soil. We conclude that this landscape is well buffered against land-use changes regarding near-surface hydrology, even though short-lived ponding and perched water tables may occur locally during high-intensity rainfall on pastures and under soybeans. KW - Land-cover change KW - Tropical forest KW - Pasture KW - Infiltrability KW - Saturated hydraulic conductivity KW - Ksat KW - Hydrological flowpaths Y1 - 2011 U6 - https://doi.org/10.1016/j.agee.2011.08.016 SN - 0167-8809 VL - 144 IS - 1 SP - 281 EP - 289 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Zimmermann, Alexander A1 - Schinn, Dustin S. A1 - Francke, Till A1 - Elsenbeer, Helmut A1 - Zimmermann, Beate T1 - Uncovering patterns of near-surface saturated hydraulic conductivity in an overland flow-controlled landscape JF - Geoderma : an international journal of soil science N2 - Saturated hydraulic conductivity (K-s) is an important soil characteristic affecting soil water storage, runoff generation and erosion processes. In some areas where high-intensity rainfall coincides with low K-s values at shallow soil depths, frequent overland flow entails dense drainage networks. Consequently, linear structures such as flowlines alternate with inter-flowline areas. So far, investigations of the spatial variability of K-s mainly relied on isotropic covariance models which are unsuitable to reveal patterns resulting from linear structures. In the present study, we applied two sampling approaches so as to adequately characterize K-s spatial variability in a tropical forest catchment that features a high density of flowlines: A classical nested sampling survey and a purposive sampling strategy adapted to the presence of flowlines. The nested sampling approach revealed the dominance of small-scale variability, which is in line with previous findings. Our purposive sampling, however, detected a strong spatial gradient: surface K-s increased substantially as a function of distance to flowline; 10 m off flowlines, values were similar to the spatial mean of K-s. This deterministic trend can be included as a fixed effect in a linear mixed modeling framework to obtain realistic spatial fields of K-s. In a next step we used probability maps based on those fields and prevailing rainfall intensities to assess the hydrological relevance of the detected pattern. This approach suggests a particularly good agreement between the probability statements of K-s exceedance and observed overland flow occurrence during wet stages of the rainy season. KW - Soil hydrology KW - Saturated hydraulic conductivity KW - Overland flow generation KW - Spatial patterns KW - Drainage network Y1 - 2013 U6 - https://doi.org/10.1016/j.geoderma.2012.11.002 SN - 0016-7061 VL - 195 IS - 169 SP - 1 EP - 11 PB - Elsevier CY - Amsterdam ER -