The evolution characteristics of the extreme precipitation in Huaihe river basin during 1960-2008

This paper studied the temporal and spatial variations of extreme precipitation in Huaihe river basin from 1960 to 2008 with the geo-spatial statistics,time series analysis and trends in diagnosis and other methods.The results showed that the extreme precipitation,precipitation intensity and the days of heavy rainfall had not significantly changed in annual and seasonal trend.The incidents without precipitation lasting over 15 d were increasing from south to north about 2-5 times per year,it happened the most in winter and the least in summer.The events with precipitation lasting over 5 d were increasing from northeast to southwest about 1-8 times per year.In the northwest of Huangchuan-Zhengyang-Zhengzhou this kind of events were the most in the fall,in other areas the events were the least in summer.In the more than 40% of sites the chance with no persistant precipitation had increased significantly.The climate trend rate was 0.22-0.60 times/a.It occurred the most in the 1970s during abruptly climatic change.The events of precipitation reduced obviously over 30% of the sites.The climate trend rate was-0.24 to-0.70 times/a,no abruptly climatic change was found.There were no obvious relationship between persistant(no) precipitation events and the annual precipitation.