长江中下游典型分汊浅滩河段二维水沙数学模型

以沙市河段为例,针对微弯分汊河段复杂的地形和河势,建立了正交曲线坐标下的平面二维水沙数学模型.考虑到阻力分布的确定是模型能否准确模拟微弯分汊河段年内主流摆动频繁、冲淤幅度大、洲滩变化剧烈等特点的关键,采用“动床率定”的方法确定糙率系数等参数,使阻力分布与地形相匹配,以提高模型的计算精度.通过对该河段水流泥沙运动过程及河床演变过程进行复演,结果表明,该模型能准确模拟该河段水流运动规律,不仅可以用于该河段复杂的冲淤变化模拟及预测,对其他浅滩河段数值模拟亦具有借鉴意义.

Two-dimensional flow and sediment mathematical model for typical multi-branched meandering reach in middle and lower reaches of Yangtze River

Taking the Shashi reach of the middle reaches of the Yangtze River for examples,a two-dimensional flow and sediment mathematical model under the body-fitted coordinate system is established based on the evolution character of multi-branched meandering channel. To simulate the characters precisely,such as the frequent migrating of main flow line,the great magnitude of deposition and erosion,the great change of island and bar,etc,it is the key to determine the distribution of resistance,we use riverbed topography at corresponding time with velocity and surface elevation profile to adjust roughness along different zones and improve the precision.The results show that the simulation precision of the model is high.The model can not only be used to simulate and predict the deposition and erosion of this complex reach,but also be practical and helpful in the research on other multi-branched meandering reach in the middle reaches of the Yangtze River.