枯水期西江径流及流域降水对ENSO事件的响应特征

The response characteristic of Xijiang River runoff and rainfall to ENSO event in the dry season

1959年以来的枯水期,珠江口出现过11次强咸潮.流域径流量是影响咸潮的直接因素,引起径流变化的主要因素是流域降水量变化,而ENSO事件是导致流域降水异常的重要因素.根据实测资料,分析枯水期西江径流及流域降水对ENSO事件的响应特征,得出:ENSO事件前一年及当年的枯水期,ONI指数与西江径流量及中、下游降水量具有显著相关性;ONI指数为负时,西江径流及中、下游降水量出现负距平的概率,后枯水期大于前枯水期;El Nino当年1～3月和La Nina次年1～3月,西江流域表现为干旱少雨径流小的特征.此外,流域降水对ENSO事件的响应特征存在显著的时空差异性.

Severe saltwater intrusions(SSI) at Pearl River estuary have occurred 11 times during the dry season since 1959,directly due to the river runoff.And the main factor affecting runoff variation is the precipitation change.While ENSO event is a major influence on precipitation anomaly.Based on observed data,the author analyzes the response characteristic of Xijiang River runoff and rainfall to ENSO event in the dry season.Results show that in dry season of the year and the previous year of ENSO phenomena,Oceanic Nino Index is significantly related to Xijiang River runoff and precipitation in the middle and lower reaches.While Oceanic Nino Index is negative,the appearance probability of the negative anomaly of Xijiang River runoff and precipitation in late dry season is higher than early dry season.In January to March of El Nino and the following January to March of La Nina,the characteristic represents lack of rainfall and low discharge in the drainage area of Xijiang river.Besides,the response characteristic of rainfall to ENSO event has significant spatial-temporal difference.