渭河流域极端降水特性指标分析

Analysis of Extreme Precipitation Characteristics in Weihe River Basin

为研究渭河流域极端降水特性指标及极端降水事件发生频率,基于渭河流域1961—2016年41个气象台站的逐日降水数据和流域历史洪水资料,选定极端降水量(R95P)、极端降水频数(RD95)、极端降水强度(RI95)和极端降水贡献率(RC95)4个极端降水特性指标,采用线性趋势法、相关分析法、Mann-Kendall突变检验法、普通克里金插值等方法,对各指标时空变化特征以及不同子流域极端降水事件的发生频率进行了分析。结果表明:(1)渭河流域极端降水阈值介于16.40~26.29 mm,流域中17%以上的气象台站极端降水阈值超过25 mm。(2)空间分布上,R95P介于127.81~201.41 mm,随纬度升高而减少;RD95干流和泾河流域较高。RI95介于24.37~39.81 mm/d,与R95P空间分布相关性较好,干流东部和下游较高,综上,渭河流域极端降水量越大的区域极端降水强度越高,未来应考虑多区域极端降水对干流及下游河道的叠加作用,降低灾害风险。(3)年际变化上,R95P和RD95变化不显著,RI95和RC95呈轻微增加趋势,2000年后增加显著。(4)渭河流域几次大洪灾均伴随着极端降水,渭河下游极端降水事件发生频率最高,主要发生于20世纪80年代初期和21世纪初期。

To study the characteristics of extreme precipitation and frequency of extreme precipitation events in Weihe River Basin,based on the daily precipitation data of 41 meteorological offices and stations and historical flood data of Weihe River Basin in the period 1961—2016,the extreme precipitation(R95P),extreme precipitation frequency(RD95),extreme precipitation intensity ratio(RI95)and extreme precipitation features(RC95)four extreme precipitation index were selected,spatial and temporal variation characteristics of each index and different frequency of extreme precipitation events sub basin were analyzed by using the linear trend method,correlation analysis,Mann-Kendall mutation test,ordinary kriging interpolation method.The results show that:(1)the threshold of extreme precipitation in the Weihe River Basin was between 16.40 mm and 26.29 mm,and the threshold of extreme precipitation in more than 17%of meteorological stations in the basin was more than 25 mm;(2)the spatial distribution of R95P was between 127.81 mm and 201.41 mm,and it decreased with the increase of latitude;RD95 main stream and Jinghe River Basin were higher;RI95 ranged from 24.37 to 39.81 mm/d,and had a good correlation with the spatial distribution of R95P.It was higher in the east and downstream of the main stream;(3)in terms of inter-annual variation,R95P and RD95 showed no significant change,while RI95 and RC95 showed a slight increase trend,and increased significantly after 2000;(4)several major floods in the Weihe River Basin were accompanied by extreme precipitation;the frequency of extreme precipitation events in the lower reaches of the Weihe River Basin was the highest,mainly occurred in the early 1980s and the early 21st century.In conclusion,the region with higher extreme precipitation in the Weihe River Basin has higher extreme precipitation intensity.In the future,the superposition effect of multi-regional extreme precipitation on the mainstream and downstream river should be considered to reduce disaster risk.