渭河流域降水时空变化与干旱特征分析

Spatial-temporal variations of precipitation and drought characteristics in Wei River Basin

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。

The Wei River Basin is located at a typical frail zone of ecological environment in the east part of northwest China,where frequent drought disasters become the major factor which restricts the sustainable development of regional economy,especially the agricultural economy.Therefore,it is important study the high and low water changes of precipitation and drought characteristics in the basin to understand the cause and development law of drought.Based on the precipitation data from 14 typical weather stations,according to the methods such as Mann-Kendall trend test,frequency analysis,differential curve,and runs analysis,variation trends of precipitation and less water probability characteristics were analyzed.The results showed that：（1）precipitation has a significantly decreasing trend,especially in spring and autumn in the recent 40 years,which increases the occurring possibility of regional drought;（2）the precipitation process presents the wet-dry alternating phenomenon,continual wet years and dry years occurring and overlapping frequently,which indicates that the drought and flood may coexist in one year;（3）the occurrence probability of continual dry years is higher than that of continual wet years,and less water period can last for2 to 3years,which leads to drought with larger intensity;and（4）the frequency and intensity of drought events have an increasing trend in Wei River Basin since 1991.Therefore,it should be paid high attention to the bigger threat of agricultural development and water safety in the future.