The flood occurence is a normalized indicator of the number of floods recorded from 1985 to 2011, using the total number of floods observed in that period. The indicator was created by the World Resources Institute (WRI) and ranges from 0-5, where 0 is lowest and 5 is highest. Values represent the "All-sector" indicator, and have been rounded to the nearest tenth by AQUASTAT.For more information, see WRI original analysis here: wri.org/publication/aqueduct-country-river-basin-rankings.Visit the FAO Aquastat website: http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en