Improving soil wetness variations monitoring from passive microwave satellite data: the case of April 2000 Hungary flood

Precipitation-runoff processes are correlated with catchment's hydrological conditions before the precipitation. Thus, an estimation of these conditions, particularly regarding soil wetness variations, is of considerable importance to improve the reliability of flood warning. In this paper, a new methodology is presented which, on the basis of microwave satellite observations, could permit us to monitor soil wetness variations at a global scale. The proposed method seems able to overcome the problems connected to surface roughness and vegetation cover that mainly limit the soil moisture estimations from satellite in the microwave region. Preliminary results achieved for the flooding event which occurred in the Carpathian basin (Hungary) in April 2000 will be described in detail. They seem to confirm the reliability of the proposed technique in the identification of different amounts of soil wetness, not only during and after the considered event, but, in order to possibly use it for warning system purposes, in the phase preceding the event as well. Such an approach is automatic and, for construction, globally exportable. Moreover, because of the complete independence from the specific satellite platform, such a technique could be easily exported to the new generation of satellite sensors with improved performances like AMSR-E aboard EOS-Aqua and MIRAS aboard SMOS.