长江中下游水沙数值模拟研究

Numerical modeling of flow-sediment transport in the middle-lower reach of the Yangtze River

根据长江中下游水沙运动特征,采用水动力学、河流动力学和数值模拟技术相结合的技术途径,建立了一、二维混合的非恒定流非均匀沙非平衡输沙的数学模拟模型,对长江中下游干流、河网区和洞庭湖水沙运动及其河床变形进行了数值模拟,并在水沙模拟的范围内着重对河网区内水沙动边界的处理、河网汊点分流分沙计算模式、动床阻力和河湖交换模式等问题进行了讨论,提出了解决问题的途径和技术处理方法。为了验证模型的适应性和有效性,采用1981年至1989年10年长江中下游水文资料对所建模型进行了检验,模拟结果较好地反映了长江中下游干流、河网区和洞庭湖水沙输运特征和河道冲淤的宏观效应。

According to the characteristics of flow-sediment transport in the middle-lower reaches of the Yangtze River system, a numerical model is established with combination of the 1-D and 2-D unsteady flow and the sediment model to simulate the transport of the flow-sediment and the bed scouring silting processes of the middle-lower reaches of the Yangtze River, Dongting Lake and their network. Some relevant problems are discussed, including the moving-boundary in the network, the computation pattems of flow-sediment diversion at channel bifurcations, the moving riverbed resistance and the exchange pattem of water-sediment among the rivers and the lake. Based on the hydrologic and topographic data of the middle-lower reach of the Yangtze River, the model verification shows good results for the flow transport characteristics and the riverbed variation patterns for the middle-lower reaches of the Yangtze River, Dongting Lake and their network.