CONTRIBUTION OF SPACE REMOTE-SENSING TO RIVER STUDIES

1. A review is presented of types of satellite remote-sensing data cur rently available, and their recent uses in studies of river systems. 2 . Broad-scale assessments of relative water quality may be carried out , although precise indication of water quality requires samples to be taken in situ. 3. In the event of flooding, the extent of inundation m ay be determined and damage assessed quickly. Some radar data allow me asurements of flood water even when obscured by vegetation. 4. Riparia n vegetation may be mapped over large areas, although the recognition of specific tree species remains difficult. 5. One of the most basic a nd widely used applications of remote-sensing data for rivers is that of mapping, both as a single event and over time to follow changes, e. g. channels in a delta. Entire catchments may be mapped, although the efficiency of detection of low-order streams is dependent upon the cha racteristics of the system used. 6. Remote-sensing data has been widel y used in all of the above types of study, but is rarely employed on a long-term basis. Several factors can explain this situation, includin g, for example, the absence of reliable absolute relationships between spectral data and ecological parameters. 7. A clear definition of obs ervational needs (e.g. spectral bands, ground resolution, acquisition frequency) of stream ecologists, together with the identification of e cological parameters that may be collected relatively easily from spac e, will improve remote sensing as an ecological tool in many restorati on and management situations.