Apracticalmethodforvisualizingfloodareaandevaluatingdamageispresented,whichconsistsoftwotechnicalapproaches:self-programmingandadaptingcommercialGISplatforms.Thelow-costandeasy-to-useGIS-Basedmodeldevelopedbyself-programmingcanmeetcurrentrequirementsofmostlocalauthorities,especiallyindevelopingcountries.Inthismodel,twocases,non-sourcefloodandsourceflood,aredistinguishedandtheSeed-spreadalgorithmsuitableforsource-floodisdiscussed;Theflooddamageisassessedbyoverlayingthefloodarearangewiththematicmapsandotherrelatedsocialandeconomicdata.andallthematicmapsareconvertedtorasterformatbeforeoverlayanalysis.Twomeasuresaretakentoimprovetheoperationefficiencyofspeedseed-spreadalgorithm.TheaccuracyofthemodelmainlydependsontheresolutionandprecisionoftheDEMdata,andtheaccuracyofregisteringallrasterlayersandthequalityofattributedata.
