Remote sensing of lakes and floodplains in the Amazon basin

Remote sensing of the lakes and floodplains in the Amazon basin has provided quantitative information on open water, floating macrophytes and flooded forests, and regional inundation. Side‐looking airborne radar (X‐band) imagery permitted measurement of lake shapes and areas. Satellite altimeters permitted estimation of stage for large rivers. Application of spectral mixture analysis to Landsat multispectral scanner and thematic mapper imagery permitted calculation of concentrations of suspended sediments in surface waters. Videography from low‐flying aircraft allowed repetitive estimation of areal extent of floating macrophytes and sediment‐laden flood waters, while clouds and smoke reduced the availability of such estimates from Landsat imagery to very few scenes per year. Application of linear mixing models to thermal emissions measured by satellite‐borne passive microwave sensors permitted determination of inundation area on a regional scale in the Amazon basin. Synthetic aperture radar sensors (on aircraft, space shuttle or satellite) have great promise for studies of macrophytes and forests on the Amazon floodplain because they are not limited by cloud cover or solar illumination, and they are sensitive to vegetation structure and are able to detect flooding beneath vegetation.