中小洪水调度对三峡水库泥沙淤积的长期影响

当前中小洪水调度对三峡水库淤积的影响尚局限在短期过程,且年内各种调度方式影响叠加,很难单独区分中小洪水调度的影响。为了解长期实行中小洪水调度对三峡库区泥沙淤积的影响,基于一维水沙数学模型,计算分析了有、无中小洪水调度情况下三峡库区泥沙淤积过程、分布特征及防洪库容保留状况。结果表明,长期实施中小洪水调度情况下,三峡水库泥沙淤积增加,影响集中在变动回水区下段及常年回水区,淤积三角洲向坝前推进较无中小洪水调度情况慢;水库达到初步淤积平衡的时间推迟约50年,平衡淤积量增加约19%,防洪库容损失约3%。

Study on Long term Impact of Small and Medium sized Floods Regulation on Sedimentation of the Three Gorges Reservoir

The impact of current small and medium sized floods regulation on the sedimentation of the Three Gorges Reservoir is still limited to short term processes, and the effects of various dispatching methods overlap each other during the year. It is difficult to distinguish the exact impact of small and medium sized flood regulation. In order to understand the long term effect of small and medium sized floods regulation on sediment deposition in the Three Gorges Reservoir area, based on a one dimensional mathematical model of flow and sediment, this paper analyzes the sedimentation process, distribution characteristics, and flood control storage capacity of the Three Gorges Reservoir area with and without medium and small floods regulation conditions. The results show that in the case of long term medium and small floods dispatching, sedimentation of the Three Gorges Reservoir increases, and the impact is concentrated on the lower section of the variable backwater area and the whole perennial backwater area. The sedimentation delta is slower than the situation of non small and medium sized floods regulation. Time to reach the initial sedimentation balance of the reservoir is delayed by about 50 years, amount of sedimentation is increased by about 19%, and the loss of flood storage capacity was at about 3% when the sedimentation comes to balance.