Physically-based water balance models require a realistic parameterisation of land surface characteristics of a catchment. Alpine areas are very complex with strong topographically-induced gradients of environmental conditions, which makes the hydrological parameterisation of Alpine catchments difficult. Within a few kilometres the water balance of a region (mountain peak or valley) can differ completely. Hence, remote sensing is invaluable for retrieving hydrologically relevant land surface parameters. The assimilation of the retrieved information into the water balance model PROMET is demonstrated for the Toce basin in Piemonte/Northern Italy. In addition to land use, albedos and leaf area indices were derived from LANDSAT-TM imagery. Runoff, modelled by a water balance approach, agreed well with observations without calibration of the hydrological model.

The Integrated Flood Forecast System (IFFS) integrates multisensor remote sensing data within an operational spatially distributed rainfall-runoff model. The aim is to improve flood forecast through a better estimation of spatial input parameters. Especially the potential of SAR data, used for the determination of topographic information and for soil moisture parameterisation, is considered. Optical data are used for the classification of the land cover, which also influences the runoff process. A first demonstration run of IFFS shows the applicability of the system and the sensitivity of the model towards soil moisture information, derived fi-om ERS SAR data.

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