Analysis on Basic Characters of Precipitation in Flood Season and Annual,Inter-decadal Variation in Binzhou City in Recent 50 Years

By using daily precipitation data in Binzhou City during 1961-2010,adopting the second,third category departure and wavelet analysis method,the basic characters and annual,inter-decadal variation of precipitation in flood season was analyzed.As indicated by the results,seasonal variation of precipitation in Binzhou City assumes one apex,the main apex situates in July;different time have different precipitation concentrated period,the annual,inter-decadal variation is obvious;rainfall in flood season shows decreasing trend;there is a long-period of 22-24 a precipitation in flood season;the delay or early,long or short and rainstorm concentrated period all have significant annual,inter-decadal variation;rainstorm has stable long-period of 23-25 a and middle-period of 12-14 a.