CONTRIBUTION OF SPACE REMOTE-SENSING TO RIVER STUDIES

1. A review is presented of types of satellite remote-sensing data currently 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 may be determined and damage assessed quickly. Some radar data allow measurements of flood water even when obscured by vegetation. 4. Riparian vegetation may be mapped over large areas, although the recognition of specific tree species remains difficult. 5. One of the most basic and 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 characteristics of the system used. 6. Remote-sensing data has been widely used in all of the above types of study, but is rarely employed on a long-term basis. Several factors can explain this situation, including, for example, the absence of reliable absolute relationships between spectral data and ecological parameters. 7. A clear definition of observational needs (e.g. spectral bands, ground resolution, acquisition frequency) of stream ecologists, together with the identification of ecological parameters that may be collected relatively easily from space, will improve remote sensing as an ecological tool in many restoration and management situations.