基于混合模型的河网输水能力计算

河网水动力数值模拟广泛应用于平原河网的防洪排涝计算,水流主要由支流向主河道汇集.而河网输水则是主河道向支流扩散的非恒定流动,需考虑支流蓄水作用对河网整体输水能力的影响.在平原河网水动力混合模型的基础上提出了一种河网输水能力计算方法.基于数字化河网划分骨干河道和蓄水支流,通过时变侧向出流形式来考虑引水时骨干河道向支流扩散的水量,从而将圣维南方程中的侧向出流项由以往的常数改进为时变流量过程,以提高河网非恒定流数值计算精度.将该方法运用到某引水工程输水计算中,有效地解决了复杂河网跨流域输水时的水量分配问题.

Calculation of water transport capacity of river networks based on mixed models

The numerical simulation of flows in river networks has been widely applied to the calculation of flood and drainage in plain area where water mainly flows from tributaries to the main stream. While the water transport through the river networks is unsteady flows from the main steam to tributaries. Under this case, the effect of water storage in tributaries on the water transport capacity should be considered. A method to calculate water transport capacity in the river networks was proposed based on the mixed models for hydrodynamics of plain river networks. The river network was divided into the mainstream and reservoirs through the digitalization, and then the time-dependent lateral flows are employed to compute the water discharge from the mainstream to reservoirs in water transportation. Accordingly, the lateral flows in the Saint-Venant equation were changed from the previous constant flows to the time-dependent ones. Thus, the precision of numerical calculations of unsteady flows in the river networks was raised. The proposed method was applied to a water transfer project, and the water allocation of a complex river network over different watersheds was effectively solved.