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 ð1 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.