Research on Characteristics of Extreme Precipitation Events in the Yellow River Delta over the Past 50 Years

Using measured daily precipitation data of 5 meteorological stations in the Yellow River delta from 1961 to 2007 and the general extreme precipitation indices suitable for the actual local conditions,the temporal characteristics of extreme precipitation events change was analyzed.The results show that the annual maximum daily precipitation,heavy precipitation days and intensity,rainstorm days and intensity present a decreasing trend in the area.From the 1960s,the extreme precipitation experiences about 3 change processes which falls first and rises later.The extreme precipitation has a good correlation with the total annual precipitation,and the correlation coefficient is more than 0.75.The annual maximum daily precipitation,heavy precipitation days and rainstorm intensity change abruptly at the end of 1970s and the beginning of 1980s,which is similar to the change characteristic in central north China.