Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake

Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of hedgerows is useful ill many fields Of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a hedgerow oil rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a hedgerow perpendicular to the slope was monitored. To evaluate hedgerow rainfall interception, rainfall was Measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 in downslope perpendicularly away from the hedgerow. The strongest correlation between rainfall next to the hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the hedgerow on spatial rainfall distribution wits related to distance from the hedgerow and rainfall amount. Annual distribution of soil-water potential showed that (lie hedgerow influenced it up to 9 in upslope and 6 m downslope, the area in which most of the hedgerow's roots were observed. The soil wits driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end Of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the hedgerow in summer and autumn. These results indicate that at the local scale hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around hedgerows should be integrated into relevant hydrological models, especially For catchments with it dense hedgerow network. Copyright (C) 2008 John Wiley & Sons, Ltd