BasedonChina'smonthlyprecipitationdatafrom1950to2000andbyusingtheZ-index,4categoriesoffloodwereestimated.VariationandchangeoffloodinSouthChinawereanalyzedintermsofpercentageareasofflood.ThisstudyrevealsthatfloodareasinSouthChinahadaslightlydecreasingtrendinthelatest50years.Duringthewinterhalfyear,however,itdisplayedanincreasingtrend,especiallysincethe1990's.ItisalsofoundthatfloodareasdecreasedduringthesummerhalfyearfromApriltoSeptember,butincreasedduringsummer,especiallysincethe1990's.Intheannuallyfirstseasonofprecipitation,thefloodareahasadecreasingtrend,butithasastronglyincreasingtrendintheannuallysecondseason.Thegradualwettrendduringthewinter-halfyearresultsinwetterclimateconditionforSouthChina,whichwillbemorefavorableforspreadingsomeoftheepidemicpathogenicbacterium,cropdiseasesandinsectpests.
