石家庄市暴雨变化特征及降水极值重现期研究

Change of Rainstorm and Extreme Value of Precipitation in Different Periods in Shijiazhuang

利用石家庄市17个地面气象观测站建站以来至2011年的逐日降水资料,在分析了石家庄市暴雨日数时空分布特征的基础上,根据耿贝尔极值Ⅰ型分布型理论,讨论了该地区在不同重现期降水极值的分布情况。结果表明:石家庄市暴雨日数由西北和东南向内部逐渐减少,其中西北部山区暴雨发生的次数最多;近几十年来,石家庄大部分地区年暴雨日数呈减少趋势,唯有北部地区呈增加趋势;石家庄市暴雨日数具有明显的年际、年代际变化特征,自19世纪70年代以来出现两个暴雨偏多时期,分别为70年代中期至80年代初和90年代中期前后;石家庄市暴雨日数存在准6 a和准16 a左右的振荡周期。在10 a、30 a和50 a不同重现期各站年最大日降水量和年最大过程降水量相差较大,其中西北部和西南部山区较大,东部平原相对较小,各站年最大日降水量均在100 mm以上,达到大暴雨的标准。

Based on the daily precipitation data observed by 17 meteorological stations in Shijiazhuang,the variation of rainstorm days was analyzed,and the distribution of extreme values of precipitation in different periods was studied using the means of Gumbel I extreme value distribution.The results showed that the rainstorm days decreased gradually from the northwest and the southeast to the central area of Shijiazhuang,and most rainstorm days occurred in the northwest.The rainstorm days decreased in most areas in recent decades,but it increased in the north.There were the obvious annual and decadal variations of rainstorm days in Shijiazhuang.The rainstorm days were more during the period from the mid-1970s to the early 1980s and around the mid-1990s since the 1970s.There were the 6-year and 16-year fluctuation periods of rainstorm days in the study area.The differences of maximum daily precipitation and maximum precipitation in a continuous precipitation process between the 10-year,30-year and 50-year periods were high,especially in the northwestern and southwestern mountainous areas.The maximum daily precipitation at all the meteorological stations was higher than 100 mm.