The Lesse basin is the prototype for testing the WAMM system. The Lesse River is a tributary of the Meuse in Belgium. The length of the river is about 70 km and the extension of the catchment is about 1400 sq. Km.. The topography of the surface is dominated by not very steep hills. The coverage is essentially characterised by cultivated and green areas with no significant urban development. Three water level and discharge gauges are present on the Lesse river and one is on the main tributary. Eight rainfall gauges are located in the catchment and other ten are placed nearby the boundary of the basin. A water level meter is located on the Meuse, close to the Lesse mouth. The calibration of the hydrodynamic and hydrological models is under way and expected to finish by the end of the summer. At present some work is being undertaken to enhance the hydrological model using SAR derived soil moisture data.