1958—2015年敦煌及周边地区极端降水事件的时空变化特征

Temporal and Spatial Variation of Extreme Precipitation Events in Dunhuang and Surrounding Areas from 1958 to 2015

敦煌阳关南临祁连山,每年汛期都会受到来自肃北、阿克塞和当地洪水的影响,2~3年就有一场特大洪灾,同时洪水携带的泥石流不仅污染了当地赖以生存的唯一水源,还造成水资源的严重破坏。基于敦煌及周边邻近1958 2015年6个气象站点全年逐日降水资料(祁连站资料为1958 2013年),采用Manner-Kendall突变检验、小波分析和Kriging插值等方法分析了敦煌及周边地区地区极端降水事件的变化趋势、周期特征及空间分布特征。结果表明,极端降水频次除了马鬃山呈现减少趋势外,敦煌、瓜州、酒泉、玉门和祁连均呈现增长趋势,极端降水频次的年倾斜增率分别为-0.063,0.127,0.072,0.138,0.104和0.638 d·(10a)^(-1);在极端降水强度突变分析中,UF统计量呈倒"V"型变化趋势,即发生了先增加后减少的变化趋势,发生变化的时间点为1980年左右;根据极端降水强度小波方差分析可知,在研究时段内敦煌、瓜州、酒泉、马鬃山、玉门和祁连控制极端降水强度的主控周期有53,22,36,56和58年时间尺度,日最大降水量、极端降水总量和极端降水强度都呈现出从西到东的梯度增加趋势空间分布特征。

Dunhuang Yangguan in the south of Qilian Mountain, where the flood season comes from the floods of Subei, Aksai and the local floods every year, it had a disastrous floods in 2-3 years, meanwhile, the flood carrying debris flow to polluted the unique survival local water sources and caused the serious damage of water resources. Sub-daily rainfall extremes may be associated with flash flooding, particularly in mountain regions, but compared with extremes on daily timescales, they have been relatively little studied in mountain regions. In the recent decade, extreme precipitation events have let to numerous flash floods in and around the Duhuang region. Based on the daily precipitation data from 1958 to 2015 （the weather station of Qilian data from 1958 to 2013） of six weather stations in Dunhuang neighborhood, that is, Mazongshan, Dunhuang, Guazhou, Jiuquan, Yumen and Qilian, period characteristics and spatial characteristics of extreme precipitation events were analyzed by the Manner-Kendall mutation test, wavelet analysis and kriging interpolation in Dunhuang area which can pro- vide the basis for water resources management and flood control and disaster reduction. The results indicated that the frequencies of extreme precipitation in Dunhuang, Guazhou, Jiuquan, Yumen and Qilian are all increasing in addition to the decreasing trend of Mazongshan. The annual rainfall increments of extreme precipitation are -0. 063, 0. 127, 0. 072, 0. 138, 0. 104 and 0. 638 d · （ 10a）-1, respectively. In the extreme precipitation in- tensity mutation analysis, the UF statistic showed the trend of ＂ V＂ type, namely, the trend of increasing first and then decreasing, The control periods of extreme precipitation intensity have 53-year, 22-year, 36-year, 56- year and 58-year time scale in Dunhuang, Guazhou, Jiuquan, Mazongshan, Yumen and Qilian according to the result of the extreme precipitation intensity wavelet analysis. Daily maximum precipitation, extreme precipitation and extreme precipitation intensity show the spatial distribution characteristics of gradient from west to east.