ENSO循环对汾河上游径流变化的影响

剖析气候对径流变化的影响,在区域水资源合理开发利用及科学管理等方面具有重要意义。基于汾河上游上静游站、汾河水库站、寨上站及兰村站1956-2000年径流数据及多变量ENSO指数(MEI),采用交叉小波分析方法,探究ENSO循环对汾河上游流域径流变化的影响。结果表明:MEI指数呈上升趋势,径流枯水期持续时间也随之增长,且MEI指数较大年份,径流量较少,反之径流量较大,径流序列的丰枯变化对ENSO循环有一定的响应关系;4个水文站径流量与MEI指数在20世纪70年代之前,有相同的1~4 a周期,且相关关系显著,同时在11~12 a尺度上具有较好的相关性,即ENSO循环对径流量影响较大;在20世纪70年代之后,虽然在1~3 a尺度上仍有一定的相关关系,但没有相同的显著周期,即ENSO循环对径流量影响相对减小,径流变化由气候驱动转变为气候与人类活动共同驱动模式。

Runoff in the Upper Reaches of Fenhe River as Affected by ENSO Cycle

The influence of climate on runoff change plays a fundamental part in water resources utilization and management. In order to explore the influence of ENSO cycle on the change of runoff in the upper reaches of Fenhe River, the annual runoff data at Shangjingyou Station, Fenhe Reservoir Station, Zhaishang Station, Lancun Station, and the multi-variable ENSO index(MEI), the data from 1956-2000 are used in this paper. Results show that MEI has an upward trend, and the duration of the dry period of runoff also increases accordingly. In addition, in years with a large MEI, the volume of runoff is little, whereas in years with a small MEI, the volume of runoff is large. The above-mentioned results indicate that the variation of runoff series has a certain response to the ENSO cycle. Before the 1970 s, the runoff data at four hydrological stations and MEI index has the same 1~4 a period, the correlation is also significant. Meanwhile, they have a good correlation during the period of 11~12 a. That is, ENSO cycle has a great impact on runoff. After the 1970 s, although a certain correlation between the runoff series and MEI on the period of 1~3 a existed, there was no similar significant periods. Therefore, the influence of ENSO cycle on the runoff is relatively reduced. And runoff changes from climate driven to climate and human activities jointly driven mode.