Spatial and temporal variations of actual soil water repellency and their influence on surface runoff |
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| Authors: | C Lemmnitz M Kuhnert O Bens A Güntner B Merz R F Hüttl |
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| Institution: | 1. Brandenburg University of Technology Cottbus, Department of Soil Protection and Recultivation, PO Box 101344, 03013 Cottbus, Germany;2. Staatsbetrieb Sachsenforst, Department 4, Unit Site Survey and Soil Monitoring, 01796 Graupa, Germany;3. GeoForschungsZentrum Potsdam (GFZ), Section 5·4 Engineering Hydrology, Telegrafenberg, 14473 Potsdam, Germany |
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| Abstract: | The increase of surface runoff at the plot scale caused by soil water repellency is a generally accepted phenomenon. However, to improve the understanding of the effect of water repellency on runoff at the catchment scale, spatio‐temporal dynamics of water repellency have to be analysed in more detail. The experimental setup of this study allowed the investigation of the relationship between water repellency and runoff generation on Quaternary and Tertiary sandy substrates while ensuring similar conditions in terms of terrain characteristics, meteorological and vegetation‐free conditions on both areas. Measurements of water drop penetration time and contact angle were carried out over a period from September 2003 to December 2005. Spatial variability of actual soil water repellency was related to heterogeneity of substrate and geomorphologic units, variations in time were related with the seasons and their meteorological conditions. To relate variable degrees of actual water repellency to surface runoff generation, both variables were measured in parallel at the plot scale (1 m × 1 m) and at the hillslope scale from September 2004 to December 2005. Soil water repellency of the Tertiary sands showed a temporal variability depending on the season, with the highest degree during summer and autumn. Variation of hydrophobicity between the seasons caused higher runoff coefficients in summer and autumn. Spatial heterogeneity of the soil water repellency revealed lower values in fine‐textured erosion rills and higher values for interrills and top areas. The measured runoff coefficients decreased from the scale of microplots to the hillslope scale due to infiltration in hydrophilic rills on the hillslope. The results suggest that improved hydrological modelling approaches on water‐repellent soils can be based on a geomorphological subdivision of the catchment area and seasonally varying infiltration parameters. Copyright © 2007 John Wiley & Sons, Ltd. |
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| Keywords: | soil water repellency hydrophobicity surface runoff generation hydrology erosion sandy soil reclaimed mining area |
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