基于多重网格的地表水文与二维水动力动态双向耦合模型研究

针对流域洪涝模拟模型的计算精度、格式稳定性及计算效率等问题，本文提出基于多重网格技术的地表水文与二维水动力动态双向耦合模型(M-DBCM)。地表水文模型采用非线性水库法模拟降雨产流和径流；二维水动力模型采用浅水方程模拟洪水演进过程。采用不同分辨率的网格划分计算区域，在粗网格区域采用地表水文模型模拟降雨径流过程；在细网格区域采用二维水动力模型模拟洪涝积水区的水流运动。地表水文和二维水动力模型通过内部耦合移动界面(Coupling Moving Interface, CMI)实现无缝连接，保证通过CMI的水量和动量等通量守恒，提高模型的模拟精度。采用时间显式格式同时求解地表水文和水动力模型，在不同区域采用不同的计算时间步长，以提高模型的计算效率。通过典型案例验证本文构建的耦合模型的性能，结果表明本文提出的动态双向耦合模型能够在保证模拟精度的同时提高计算效率。

Dynamic bidirectional coupling of surface hydrological and 2D hydrodynamic models based on multi-grid technique

Aiming at improving the computational efficiency without accuracy losses for flood simulation in watershed,a dynamic bidirectional coupled surface hydrological and 2D hydrodynamic models based on multi-grid (M-DBCM) is proposed in this study.The 2D nonlinear reservoir method is adopted in surface hydrological model to simulate the rainfall-runoff,whereas the 2D shallow water equations are adopted in 2D hydrodynamic model to detail the flood process.The computational domain is divided into grids with different sizes.The surface hydrological model is used to simulate the rainfall-runoff on coarse grids,whereas the dynamic bidirectional coupled surface hydrological and 2D hydrodynamic models is used to detail the flood process on fine grids.A coupling moving interface (CMI) is developed to couple the surface hydrological and 2D hydrodynamic models.The mass and momentum conservation through the CMI can be ensured to improve the simulation accuracy.Different time steps are adopted in coarse and fine grids to further improve computational efficiency.Two test cases are employed to demonstrate the performance of the proposed model.The results show that the proposed M-DBCM has high computational efficiency while maintaining satisfactory accuracy.