突变前后湖南株洲市设计暴雨参数变化特征

Variation Characteristics of Designed Rainstorm Parameters Before and After Climate Mutation in Zhuzhou of Hunan Province

近年来,湖南株洲市暴雨呈多发之势,城市内涝日趋严重,排水防涝设计暴雨参数发生变化。利用湖南株洲市国家基准站1963-2017年逐分钟降水资料,通过滑动平均提取16个历时逐年最大降水量样本,探讨株洲市气候突变前后设计暴雨强度及雨型的变化特征。结果表明:湖南株洲市暴雨日数及年最大降水量在1983年存在一次显著突变,突变后暴雨日数增多、雨强增大,极端降水事件增多。突变前,各历时年最大降水量的变化趋势不一致且不显著,而突变后则均呈现明显增加趋势,且120 min及以上历时通过显著性检验。突变前后不同重现期下各历时暴雨雨量都有不同幅度的增大,且随着重现期增大、历时延长,雨量差值增大。短历时和长历时暴雨雨型突变后都出现雨峰位置前移、雨峰雨量增大现象,这在一定程度上解释了近年来株洲市城市内涝频发的原因。

In recent years, the rainstorm occurred frequently in Zhuzhou of Hunan Province, which caused increasingly serious urban water-logging, and the rainstorm parameters of drain and flood control design had changed obviously. Based on minutely precipitation from 1963 to 2017 at Zhuzhou weather station, the samples of annual maximum precipitation with sixteen durations were selected by using the moving average method, and the variation characteristics of designed rainstorm intensity and pattern before and after climate abrupt change in Zhuzhou were discussed. The results show that rainstorm days and annual maximum precipitation had an obvious abrupt change in 1983 in Zhuzhou of Hunan Province. After the mutation, rainstorm days increased and rainstorm intensity strengthened, which caused the increase of extreme precipitation events in Zhuzhou. Before the mutation, the change trends of annual maximum precipitation with different durations were inconsistent and non-significant, while they showed obvious increasing tendency after the mutation, and the precipitation with duration 120 minutes and above passed the significance test. The precipitation of rainstorm with different durations increased under different recurrence periods after the mutation, and the difference of precipitation before and after the mutation increased with increase of recurrence period and extension of duration. The position and precipitation of rain peak for short-time and long-time rainstorm pattern moved forward and increased after the mutation, respectively, which partly explained why the water-logging was frequent in Zhuzhou in recent years.