基于SPI的渭河流域干旱特征演变研究

Evolution of drought characteristics in the Weihe River Basin based on standardized precipitation index

基于渭河流域21个气象站的1961-2010年的标准降水指数(SPI),采用Mann-Kendall趋势检验法研究了各个站点12个月份的SPI、干旱严重程度以及干旱历时的变化趋势,最后运用Copula函数计算了渭河流域两种典型干旱情景下的联合重现期。得到主要结论如下:(1)整个渭河流域干旱趋势明显,其中干旱化显著的月份主要有11、12以及1月,而有湿润化趋势的月份主要集中在7、8月份,此外,干旱严重程度与干旱历时的变化趋势均不显著;总的来说,该流域干旱季节越干旱而湿润季节越湿润的趋势进一步加大了水资源管理的难度,渭河流域存在较大的旱涝风险;(2)就"且"重现期而言,渭河流域发生典型中度干旱和典型重度干旱的联合重现分别为28.9年和53.1年一遇;整个渭河流域发生中度干旱的可能性大,流域西北部发生旱灾的概率要大于东南部。因此,相关部门应该加大渭河流域西北部干旱监测力度,提前做好防灾减灾的准备。

Based on the standardized precipitation index( SPI) values of 21 meteorological station in Weihe Wei River Basin in 1951- 2010,the Mann-Kendall trend test method was used to investigate the trends of the SPI values in 12 months at each station,drought severity and drought duration,and Copulas functions were employed in this last to calculate the joint return period of two typical drought events in the Weihe River Basin. The main results obtained in the study are as follows:( 1) the whole basin has a striking trend of droughts,and the significant drought months are concentrated in November,December and January, while the wet months are primarily concentrated in July and August,moreover,the trends of drought severity and duration are nonsignificant; generally speaking,the trend towards drier in the dry season and wetter in the wet season further increase the difficulty of water resources management in the Weihe River Basin,and this basin has a high risk of drought and flood( 2) in terms of the 'and'return period,the return periods of the typical moderate drought and severe drought in the Weihe River Basin are 28. 9 and 53. 1 years,respectively; the probability of the occurrence of the moderate droughtin the whole basin is large,and the probability of the drought in the northwestern basin is larger than that of the southeastern basin. Therefore,the relevant department should enhance the intensity of drought monitoring in the northwestern basin and take measures to prevent and reduce disaster in advance.