Trends in precipitation extremes over the Yangtze River basin

Based on the daily observational precipitation data of 147 stations in the Yangtze River basin during 1960-2005,the projected daily data at 79 grids from ECHAM5/MPI-OM in the 20th and the former half of the 21st century,time series of precipitation extremes which contain AM(Annual Maximum) and MI (Munger Index) are constructed.To quantify the characteristics of flood-drought events over the Yangtze River Basin,four distribution functions are used,namely,General Extreme value (GEV),General Pareto (GPA),General Logistic (GLO) and Wakeby (WAK).It is proved that WAK can describe the probability distribution of precipitation extremes quite well calculated from observed and projected data..The return period of precipitation extremes show spatially different changes under thee greenhouse gases emission scenarios.The 50-year heavy precipitation and drought events from simulated data during 1951-2000 will be more frequent and become the 25-year events for the most midlower Yangtze region in 2001-2050.The changing character of return levels of precipitation extremes should be taken into account for the future water resource management.