天然河道与矩形水槽交汇口水面形态特性差异分析

鉴于天然河道与矩形水槽交汇口水面形态变化规律一致,定量分析上存在差异的问题,基于MIKE21FM建立天然河道阜新细河与支流汤头河交汇口的水动力数学模型,模型应用有限体积法求解浅水方程,通过对比模拟水面线与实测洪痕推算水面线,表明该模型能较好地模拟交汇口水流运动过程。利用该模型模拟不同分流比条件下天然河道交汇口水流运动,分析交汇口处的水面横比降、纵比降、分离区特征值与已有矩形水槽研究结果的差异。结果表明,天然河道断面形态由单一的横比降向凸脊形过渡发生在汇流比为0.5时,大于矩形水槽汇流比0.4;随着汇流比的增大,天然河道上游干流纵比降减小速率与矩形水槽基本一致,支流上游纵比降增大速率小于矩形水槽,干流下游纵比降增大速率大于矩形水槽;天然河道分离区的形状指标与收缩系数均大于矩形水槽,并给出了形状指标、收缩系数与汇流比的一般关系式。研究结果可用于指导河道整治、河网和河道设计等领域的实际工作。

Difference Analysis of Water Surface Morphology between Natural River and Rectangular Sink Junction

The changes of water surface morphology between natural river and rectangular sink are consistent, there are differences in quantitative analysis. Based on MIKE21 FM model, the hydrodynamic model of the junction of the Xihe River and the tributary of the Tangtou River in Fuxin was established. The finite volume method was used to solve the shallow water equation. The comparison of the simulated water level and the measured flood mark shows that the model can simulate the flow of water in the junction better. The model was used to simulate the flow of water at the junction of natural river channels under different diversion ratios. The differences of water surface transverse ratio, longitudinal ratio drop, separation zone characteristic value with the existing rectangular sink were analyzed. The results show that the transition from the single transverse to the ridge of the natural river channel occurs when the confluence ratio is 0.5, which is larger than that of the rectangular sink confluence ratio 0.4. With the increase of the confluence ratio, the natural flow rate of the natural river channel is basically the same as that of the rectangular sink, the increasing ratio of longitudinal upstream of the tributary is smaller than that of the rectangular sink, and the increasing ratio of the longitudinal ratio is larger than that of the rectangular sink. The shape index and shrinkage coefficient of the natural river separation zone are larger than those of the rectangular sink. The general relation of shape index, shrinkage coefficient and confluence ratio were given. The results can be used to guide practical work in areas such as river regulation, river networks and river design.