The influence of hedgerow systems on the hydrology of agricultural catchments in a temperate climate
The bocage landscape is an ancient system of organising rural areas by using a hedge network enclosing fields and meadows. It is one form of hedgerow systems used as a windbreak, water and erosion barrier, or ecological corridor in numerous regions around the world. Its hydrological impact in temperate countries is poorly known, although paradoxically often cited as important. This paper is a literature review of researches concerning the hydrologic effects of hedgerow systems mainly conducted in the region of Brittany, in France, for the last 20 years. The actual or potential evapotranspiration seems little modified by hedges at the catchment scale for a bocage with a hedge density of approximately 100 m.ha(-1). However, local effects are observed on the actual evapotranspiration around the hedges in summer. No effect on the annual rainfall has been measured, but the spatial heterogeneity of the rainfall distribution increases close to the hedge. The bocage has a buffering effect on quick flow during storm runoff of high frequency, modifying the Hortonian overland flow and the contributing flow on saturated areas. The bank and the hedge surrounding the bottom land are the key factor for hydrological effects. Water erosion is limited in bocage landscape, with no exportation outside the catchment. (C) 1999 Inra/Editions scientifiques et medicales Elsevier SAS.
Author(s): Merot, P