三峡水库二期蓄水初期螺山站水位流量变化响应

Response of Water Level and Discharge of Luoshan Station to the Initial Operation Stage of the Three Gorges Project

三峡工程二期蓄水对坝下游江段水情的变化产生了一定的影响。在水库蓄水的初期阶段,分析螺山江段水位流量的变化响应,采用综合落差指数法描述了该河段水位流量关系的变化,并通过同流量水位法初步探悉了该河段近几年河床冲淤变化情况。结果表明,水库蓄水后,枯水期该站月径流量占径流量的百分比上升了0.43%,丰水期和平水期分别下降了0.2%和0.23%;从该站水位距平值来看,枯水期有所上升,丰水期和平水期均有所下降。对该站水位流量关系进行单值化处理后,发现蓄水后水位流量关系曲线较蓄水前偏左。同时,同流量下水位的变化也反映了该河段泥沙冲淤情况,对此本文作了初步探悉,发现在同一江段的不同时段都有冲淤的变化。

The impoundment of the Three Gorges Project brings effect on the hydrological variation of middle and lower reaches of the dam. At the initial period of impoundment, the paper analyzes variations of water level and discharge at Luoshan station, and describes the changing of the stage-discharge relationship by the synthesis fall exponent method. Then it primarily learns the variations of riverbed sediment erosion in recent years. As a result,the percentage of monthly discharge to annual runoff raised by 0. 43% in low water period, while it descends 0. 2% and 0.23% respectively in flood period and in level period. The difference with month average value of water level also raises after im- poundment in low water period, while descending in flood and level period. After unfformized treatment of the stage-discharge relationship of Luoshan hydrometric station,it was found that the curve of the stage-discharge relationship after impoundment is on the left side. Synchronously, the water level variation with the same discharge reflects the changes in erosion and deposition at this reach. This paper does a pilot study and finds that there are changes in erosion and deposition in different periods of the same reach.