Rapidly assessing the flood disaster by using remote sensing and GIS

The method of rapidly assessing the flood disaster is discussed here by using the technologies of remote sensing and geographic information system (GIS). The method included four steps. Firstly, satellite SAR image such as Radarsat SAR or ERS SAR is geometrically corrected and matched with the data from the GIS database such as landuse or the geometrical-corrected Landsat TM image. Secondly, the flood extent can be extracted from SAR images by visual interpretation or automatic extraction with support of DEM or Landsat TM. Thirdly, the flood extent can be over-laid with the data such as landuse data from GIS database or Landsat TM. Fourthly, the results such as map and table can be obtained by using GIS. The case of assessing the large flood disaster of P.R. China in 1998 showed that the technologies are very useful tools for assessing the flood disaster, which provides the government with very important information for alleviating the flood damage.