In water resources management and in flood risk analysis the hydrological response is strongly dependent on the local soil characteristics, such as porosity and water storage capacity, which affect infiltration rates and river flow. Considering the non-linear interaction between the complex spatial rainfall distribution and the variability of soil hydraulic properties, a distributed approach is considered fundamental to model the hydrological phenomena and runoff dynamic at the basin scale.

Within the research activity for the evaluation of flood conditions in the Arno river basin (Italy), the feasibility of an operational real-time monitoring system is analyzed in order to investigate the hydro-meteorological phenomena and to increase the time of forecasting. One of the components of the system is a hydrological distributed model, devoted to simulate the evolution and the variability of the primary process involved in the hydrological cycle and flood routing. The model is calibrated both with regard to the hydraulic response at different river cross sections, and to the ability in reconstructing the spatial variability of soil moisture through the comparison with soil moisture fields from remote sensing. Due to the non-linearity of the involved phenomena and the high number of parameters, which characterize the behavior of the basin, the development of robust techniques of inverse estimation is required, in order to minimize the model residuals. The model can also be used for the analysis of the role of rainfall field on the spatial distribution of soil moisture and the recognition of moisture patterns as a result of the interaction among soil type characteristics, basin's geomorphology and spatial structure of the atmospheric forcing. It can also provide a better understanding of the response times of the basin not only in terms of discharges but also of distributed soil hydrological conditions.