Analyses on the Temporal Trends and Spatial Distributions of Floods and Droughts in China

Under the background of earth’s climate change, meteorological disasters are occurring frequently and suddenly because of extreme weather events happening frequently in recent decades. In China, as a result of extreme rainfall events and long-time dry weather, floods and droughts are the most serious and frequent among all meteorological disasters. Thus, the temporal trends of loss indexes of floods and droughts from 1950 to 2012 are analyzed by three trend test methods (Linear tendency method, Polynomial trend method and Mann-Kendall test method). It’s shown that the amount of economic and social losses caused by floods and droughts has been increasing throughout the study period in China. This situation is especially severe in 21th Century when the disasters become more complex and serious. Then the weighty floods and droughts are respectively defined by logical formulas according to their consequences. And their spatial distributions are shown by GIS. The result shows that the weighty floods mainly occur in the south China whereas the weighty droughts cover across the whole country. The areas which are affected most heavily by weighty floods include Hubei, Hunan and Sichuan Province. However, the weighty droughts happened nationally, mainly including Inner Mongol, Jining, Yunnan and Guangxi Province. Overall, South and Middle East China suffer more from floods and droughts than North and North-West regions in 21th Century.