渭河流域降水时空变化与干旱特征分析

以渭河流域14个典型气象站降水资料为基础,应用Mann-Kendall趋势检验法、频率分析法、差积曲线法以及游程分析法对研究区的降水变化规律及少水概率特征进行了研究。结果显示:40多年来渭河流域降水量呈明显减少趋势,以春、秋两季最为明显,这增加了区域发生干旱的可能性;流域降水过程呈丰枯交替的周期性现象,连丰或连枯较易发生,且存在干旱与洪涝并发现象;连枯年的概率比连丰年概率大,且少水期常持续2~3a,引发的干旱强度较大;1991年以后渭河流域干旱事件的频率、强度和烈度均有增加趋势,未来渭河流域的农业发展与水安全将面临更大的威胁,必须予以高度关注。

Spatial2temporal variations of precipitation and drought characteristics in Wei River Basin

The Wei River Basin is located at a ty pical fr ail zo ne of eco log ical env ir onment in the east par t o f nor thwest China, where fr equent dro ug ht disaster s become the majo r factor which restr icts the sustainable dev elopment of r eg io nal economy , es2 pecially the ag ricultural eco nomy. Therefor e, it is impor tant study t he hig h and low water chang es o f precipitation and droug ht char acter istics in the basin to understand the cause and development law of dr ought. Based on the pr ecipitation data from 14 typ2 ical weather stat ions, accor ding to the methods such as Mann2Kendall t rend test, fr equency analysis, differ ential curve, and runs analysis, variation tr ends of precipitation and less wat er probability char acter istics wer e analyzed. The r esults showed that: ( 1) pr ecipitatio n has a signif icantly decreasing tr end, especially in spr ing and autumn in the r ecent 40 years, which increases the oc2 curr ing possibility of reg ional droug ht; ( 2) the precipit ation pr ocess presents the w et2dr y alt ernating phenomenon, continual wet years and dr y year s occur ring and ov erla pping frequent ly , w hich indicat es that the dr ought and flood may coex ist in one y ear; ( 3) the occurr ence pro babilit y o f continual dry year s is higher than that o f co ntinual w et y ear s, and less w ater perio d can last for 2 t o 3 y ears, w hich leads t o dro ught w ith lar ger intensity ; and ( 4) the frequency and intensity o f droug ht events have an increas2 ing trend in Wei River Basin since 1991. Therefo re, it sho uld be pa id hig h attent ion to the bigg er threat o f agr icultural develop2 ment and w ater safety in t he future.