三峡水库蓄水后库区干流泥沙含量时空变化研究

Research on temporal and spatial variation of sediment content in mainstream after impoundment of Three Gorges Reservoir

由于水体中某些污染物会以吸附态的形式吸附在泥沙上,因此,分析水库形成后水体中泥沙含量变化对研究水环境的变化具有积极意义。以实测泥沙资料为依据,分析了三峡水库蓄水前后2个多月相似年份干流泥沙含量时空分布的变化。结果表明,正常蓄水位实现后的第一年,同蓄水前相比,库区干流泥沙含量发生了很大变化,从库中至库首的干流江段,泥沙含量年均值比蓄水前下降了90%以上,且汛期下降幅度最大;同一水域泥沙含量的季节性差异比蓄水前明显减小。蓄水后从库尾至库首泥沙含量呈明显的沿程下降趋势。库区干流泥沙含量在蓄水后出现的新特征,可合理解释某些水质参数浓度的变化。

Since some pollutants in the water will be absorbed to the sediment, so the analysis of sediment content variation af- ter reservoir impoundment has an important significance to the research of water environment change. According to measured da- ta, the sediment content variation in the Three Gorges Reservoir in 2 years with similar water quantity before and after its im- poundment is analyzed. The results show that compared with the years before impoundment, the sediment content in the main- stream in the first year after 175 m impoundment changed greatly; from the middle of reservoir to the dam, the average sediment content decreased by more than 90% compared with that before impoundment, especially in flood season; the seasonal difference of the same water zone obviously becomes smaller compared with that before impoundment; the sediment content deceases obvi- ously from the reservoir tail to the head. The new characteristics of sediment content in the mainstream after impoundment can reasonably explain the variation cause of some water quality parameters.