Hydrological processes controlling flow generation in a small Mediterranean catchment under karstic influence

The hydrological behaviour of the River Vene (67 km(2), south of France) was assessed through a coupled approach based on field observations and modelling. The origins of runoff were identified by analysing discharge and water conductivity data. During rainfall events, natural areas did not contribute to runoff. In these areas, infiltration fed the karstic aquifer and contributed to spring discharges. Urban areas were characterized by a rather constant runoff coefficient whose value compares well with the extent of urbanisation and explains the total volume of small floods. Agricultural areas did not contribute directly to the flood peak, and subsurface flow in unsaturated areas was the major hydrological process during flood recession. A mathematical model, based on this perceptual model, confirmed the hydrological processes identified and helped quantify the functioning thresholds in this intermittent river.