Spatial organization of hydrological processes in small catchments derived from advanced SAR image processing: Field work and preliminary results

The presented research focusses on the use of active microwave observations to retrieve hydrologically relevant information of surface characteristics (i.e. soil moisture and surface roughness) in river catchments. Given the availability of pairs of SAR data from the tandem mission the following research issues are addressed: (1) development and testing of improved retrieval algorithms for surface characteristics based on the combined use of phase and magnitude information of the return signal from active microwave sensors; (2) use of high resolution field collected data and remotely sensed data to test and validate theories for the catchment scale estimation of soil moisture integrated over soil depth. In particular questions to be investigated include: (2a) what spatial resolution is required for estimation of spatial average soil moisture patterns over a range of scales; (2b) what temporal resolution is required for accurate estimation of the time series of soil moisture.; (2c) what spatial and temporal resolution of data is required to obtain information about the dynamics of soil moisture redistribution within the soil profile using distributed hydrological modelling; (3) study of the influence that spatial organization of soil moisture and vegetation on SAR-based soil moisture retrieval, and of the ability to identify such organization using ERS data. In order to accomplish these objectives extensive field campaigns are organized in two small experimental catchments (Tarrawarra near Melbourne, Australia and Wijlegemse beek near Gent, Belgium). For both catchments a number of ERS-1/2 tandem scenes have been collected. Both Single Look Complex (SLC) and Precision Image (PRI) data will be required to carry out the different steps in the proposed project.