Abstract: After ten years’ operation，the actual sedimentation in the Three Gorges Reservoir (TGR) shows quite a difference from that estimated in demonstration phases due to the changes of incoming flow and sediment, which shows a great need improving its waterway transit capacity. The total sedimentation in the TGR is about 1.5 billion tons, which is mainly distributed at the wide and bend reaches in the permanent backwater region, and no cumulative sedimentation exists in the gorges, and the median particle diameter of the sedimentation is less than 0.01mm. Sedimentation of pebble is concentrated in the fluctuating backwater area, but the deposition amount is relatively small. Navigation obstacles caused by suspended sedimentation have taken place at Huanghuacheng waterway in permanent backwater region owing to the occurrence of bed load movement at some waterways in the fluctuating backwater area during the falling stage. Based on field measurements, mathematical models and physical models, a sedimentation model is proposed in the TGR, and has been successfully applied in the mathematical model and physical model of Huanghuacheng waterway. Based on the two-dimensional water-sediment mathematical model, it is concluded that the retrogressive sedimentation will be less than that expected, facilitating the waterway transit capacity improvement in fluctuating backwater area, and a preliminary treatment is put forward for the construction of the ‘4.5m-deep waterway’.

Key words: waterway sediment, sedimentation model, waterway transit capacity, the Three Gorges Reservoir

摘要： 三峡入库水沙条件发生变化，运行十年来的泥沙淤积与论证阶段存在差异，库区航道通过能力提升建设面临新的问题。实测资料分析表明：库区泥沙淤积总量约为15亿t，淤积物中值粒径多在0.01 mm以下，主要分布在常年回水区的宽谷和弯道河段，峡谷段无累积性淤积；卵石淤积集中在变动回水区，但累积性淤积不大；常年库区黄花城航道已发生悬移质淤积碍航，变动回水区消落期部分航槽推移质运动存在碍航。基于现场测量、数学模型和物理模型等，提出了三峡库区航道泥沙淤积模式，成功应用于典型细沙淤积碍航河段黄花城水道治理方案的数学模型和物理模型中。针对变动回水区航道通过能力提升问题，基于全库区二维水沙数学模型预测得出库尾泥沙溯源淤积将没有预期严重，可进行4.5 m深水航道的建设，并提出了初步治理思路。

关键词: 航道泥沙, 淤积模式, 通航能力, 三峡水库