Contribution of remote sensing to hydrological modelling

Abstract

Different studies have shown how the soil moisture state influences the behaviour of the basin rainfall-runoff relationship. After being assimilated in hydrological models, this variable may improve outflow forecasting methods on agricultural river basin. Now, several surface parameters, like soil moisture, which allow to follow the soil water budget, may be inferred from space remote sensing. The present paper reports on an investigation in central Brittany (France) using radar and optical remotely sensed data. Ground truth data have been compared with ERS-1/SAR data at the basin scale. The results confirm the capability of monitoring surface soil moisture during the periods of low vegetation density with the space-borne ERS-1/SAR. The second aspect of the project is the development of a hydrological model taking into account soil and vegetation cover to simulate soil moisture and outflows. The results of the simulation are generaly in good agreement with the measurements, the assimilation of combinated remote sensed data in the model is in progress in order to validate the methodology. The possibility of application of this methodology in operational hydrology is discussed.