China's water issues are mainly manifested in threats of floods and drought disasters, shortage of water resources and deterioration of the eco-environment of the 21st century. Among the three problems, the shortage of water resources has become the important restrict factor for the sustainable development of society and economy. Therefore, it is essential to evaluate the degree of the drought of a district and work out the drought preparedness plans. Using data of annual precipitation and evaporation, river runoff and drought disaster affected cropping areas, the temporal distribution of regional drought in Hunan Province during 1960-2005 is analyzed by fuzzy comprehensive evaluation, M-K test, wavelet analysis, abrupt change analysis, cluster analysis, EOF and REOF. In addition, the responses between regional drought-flood in Hunan Province and global change are studied.
(1)Using an appropriate evaluation system, the fuzzy comprehensive evaluation model was established, and the level of regional drought-flood was identified.
(2)The results showed that the composite indicator in Hunan Province has a weak increasing trend in the past 36 years, of which the 1970s and 1990s were in flood periods, the 1980s were in drought period. There was a decreasing trend upon entering the 21st century, and there was an abrupt change from dry to wet in the early 1990s. Generally, the composite indicator presented variations of three periods. In the late 2000s, Hunan Province will be in a period of drought, after that it will be in a period of flood.