ENSO事件与渭河径流变异的响应关系

为研究ENSO事件对径流变异的影响,以渭河干流华县水文站和支流北洛河状头水文站的还原年径流流量之和作为渭河流域出口流量,采用其1956—2010年径流系列,分析了ENSO事件与渭河流域径流变异的响应关系.结果表明:渭河流域径流量的丰枯变化和变异与ENSO事件都有明显的对应关系,El Nio事件发生年径流偏枯概率较大,La Nia事件发生年径流偏丰概率较大.采用曼-肯德尔(Mann-Kendall)非参数统计检验方法,对渭河流域径流序列进行了变异诊断,得到变异点为1991—1992年;径流变异年份也是El Nio事件发生强烈年;采用Pearson、Kendall、Spearman法对变异点前ENSO事件的不同强度发生年月径流序列与变异年份月径流序列相关性进行检验,表明径流变异年份1991—1992年与El Nio事件年1987年,与La Nia事件年1970年、1956年和1988年在0.01水平(双侧)上显著相关,有明显的响应关系.

The Relationship of ENSO Events and Runoff Variation in Weihe River Basin

In order to study the influences of ENSO events on runoff variation, taking the sum of restoring annual runoff of Huaxian County and Zhuangtou hydrologic stations （located respectively in Weihe River mainstream and north Luohe River tributary） as the out-let flow of Weihe River basin, using the annual runoff series from 1956 to 2010, the relationship of ENSO events and runoff variation was analyzed. The results showed that there was an obviously relationship between runoff change and variation and ENSO events, the probability of low runoff flow was bigger when E1 Nino event occurred, while the probability of high runoff flow was bigger when La Nina event occurred. Then Mann-kendall method was used to analyze the variation diagnosis of the annual runoff series in Weihe River ba-sin. The results showed that the variation point was from 1991 to 1992, and El Nino event also occurred intensely in the variation year. Three methods of Pearson, Kendall and Spearman were used to analyze the correlation between ENSO events in different grades and monthly runoff series before and after the variation point in Weihe River basin. The results showed that monthly runoff have significant correlation at 0. 01 level （double side） in 1987 El Nino year and 1970, 1956, 1988 La Nina years. There was obvious response rela-tionship between ENSO events and runoff variation.