Abstract: The accumulated siltation and sediment in Three Gorges reservoir zone caused new problem to the daily management, maintenance and regulation of waterway. In this paper, the 2D flow-sediment mathematical model was established to simulate the muddy sand transport in the Three Gorges Reservoir regional backwater variation zone in the river reach from Changshou to Luoqi. Sensitivity analysis shows that sediment input factor is key parameter influencing sedimentation volume. Water level, flow velocity and direction and topography verifications show that this mathematical model calculation results well reflect the reality hydrology and siltation. The calculation results show that subject to the influence of backwater of the Three Gorges Reservoir, cumulative deposition happens in the reach from Changshou to Luoqi and siltation zones are located primarily in the river sinuses，the backflow zones and broad-shallow reaches of the river and siltation mainly occurred in deep trench and side beach in flooding season from June to September. Because of the siltation and sediment, water depth at upper and lower reaches of Luoqi and Wangjiatan is insufficient so as to impede navigation. It is suggested to enhance monitoring and take timely rectification and regulating measures.

Key words: channel engineering, flow-sediment mathematical model, Three Gorges project, backwater variation zone, river bed evolution

摘要： 三峡库区泥沙累积性淤积给航道的日常维护管理以及航道整治带来了新的问题。建立了二维水沙数学模型对三峡库区回水变动区长寿至洛碛河段的泥沙输移进行了数值模拟。敏感性分析表明输沙因子对泥沙淤积量影响最大。水位、流速流向和地形验证表明：数模计算成果较好地反映了实际水文、泥沙淤积情况。计算表明：受三峡回水影响，长寿至洛碛河段发生累积性的泥沙淤积，淤积区主要位于岸线凹凸不平的弯沱、回流区及河道的宽浅河段，淤积部位主要是深槽和边滩。淤积时间在每年的汛期6—9月份。受泥沙淤积影响，上、下洛碛和王家滩在低水位时航深不足，有碍航现象，建议加强监测，及时采取整治措施。

关键词: 航道工程, 水沙数学模型, 三峡工程, 回水变动区, 河床演变