中文摘要：

针对长江中游宜昌至枝城河段卵石夹沙河床级配分布宽等特点，建立了非均匀悬沙、底沙二维数学模型，尤其是考虑了底沙的不平衡输移及冲淤过程中床沙的级配调整问题，对计算中的关键问题提出了处理方法，利用水文、泥沙及河床变形资料对模型进行了水面线、流速分布及冲淤过程的详细验证，尤其是进行了葛洲坝水利枢纽运用后、1998年洪水前后及三峡工程运用后的验证。在此基础上，根据设计单位一维数模提供的水沙边界条件，预测了三峡工程蓄水初期该河段的冲刷量、分布及床沙粗化过程。

英文摘要：

With regard to the characteristics of wide size-distribution with gravel and sand bed between Yichang and Zhicheng in the middle reaches of the Yangtze River, a 2D mathematical model for nonuniform suspended load and bed load are developed, which especially takes into account the nonequilibrium bed material transport and the grain size changes of the eroison process, and suggests the solving methods for some key problems. Some model parameters are calibrated by means of plenty of flow, the river bed deformation data, the water surface profile, the distribution of flow velocity and the riverbed deformation are verified against field data, especially the riverbed deformation during different periods such as the impoundment of the Gezhouba, round about the 1998 flood and the initial impoundment of the Three Gorges Project（TGP）. Based on the flow and sediment conditions provided by ID model from the design unit, the amount and distribution of erosion and deposition, the armoring process of the bed material in the study reach are predicated during the initial impoundable stage of the TGP.