The Roujan catchment (0.91 km2) is located in Southern France,
60 kmwest of Montpellier, with central coordinates of 43.498Nand
03.328E. The climate is Mediterranean sub-humid with a
prolonged dry season in summer. Rainfall is usually of high
intensity and short duration and presents large year-to-year
variability. Inter-annual precipitation is about 650 mm; interannual potential evapotranspiration is about 1100 mm. The soils of the catchment developed from marine, lacustrine or fluvial sediments (Andrieux et al., 1993).