Wetland changes and droughts in southwestern China

The five provinces of southwestern China, Sichuan, Chongqing, Guizhou, Yunnan and Guangxi, frequently suffer from droughts, especially the recent severe drought of five consecutive months from autumn 2009 to spring 2010, which caused serious water shortages, huge economic losses and adverse social consequences. With increasing human activity in the last 200 years, the wetland areas have decreased and their ecological functions such as water conservation, climate regulation have declined, which has a direct impact on climate and the ecological environment. Using satellite images, changes in wetland areas of the five provinces of southwestern China have been mapped from 1970 to 2008. Our detailed analysis shows that the wetland area in the 1970s, 1990, 2000 and 2008 occupy an area of 20822.9, 18386.16, 19904.22 and 17269.72 km(2), respectively, which indicate that the wetland areas have a downtrend, at an accelerating rate, from 2000 to 2008. Considering the complexity between wetland change and drought, the correlation between spatial and temporal wetland change and drought have been analysed using monthly ground meteorological data from 1971 to 2009, obtained from the China Meteorological Data Sharing Service Network. The analysed results show that the decrease of the wetland area, damage to biological resources and decline in climate regulation function are closely related to serious drought problems in the five provinces of southwestern China. Finally the corresponding solutions are discussed by analysing the problems faced by the wetland ecological system.