Cartographie de la perméabilité des sols pour l'aide à la prévision des crues ; cas d'étude sur le Gardon d'Anduze : Soil infiltration capacity mapping for flood prevention ; case study on the Gardon d'Anduze catchment

Abstract : Soil permeability is an important input parameter of several physical hydrological model used by Flooding Forecast Services : On the Gardon d'Anduze catchment selected by SCHAPI as experimental catchment for flash floods, permeability measurements were done between 2002 and 2007 by the French Geological Survey. A statistical analysis allowed to calculate the permeability of each unit combining information on soil and land use and so to propose a permeability map for the catchment. This map was validated using the runoff model STREAM.With this model, correlation between simulated and observed discharges (0.83) is satisfactory when using distributed soil permeability for Gardon d'Anduze catchment or Mialet and Saumane sub catchment. Correlation significantly decreases (0.66) when using STREAM with an homogeneous averaged permeability value of 30 mm/hour for the catchment. This showed clearly the importance of distributed soil permeability for runoff modelling with a hortonian model a Mediterranean catchment.