Abstract We present the development of a high-efficiency and high-resolution subgrid model for simulating surface water and groundwater interaction in coastal regions. The governing equations are derived based on an assumption of the fully-saturated subsurface flow and a phase-averaging method, in which two phase functions are defined respectively for the surface phase and subsurface phase at the subgrid level. Both the surface water and groundwater processes are modeled by solving the phase-averaged equations on a coarse grid, taking into account the subgrid effects. Model validation with laboratory data indicates that the subgrid model is capable of simulating flow processes within permeable structures. The model was applied to simulating flooding and draining processes and the interaction of surface flows and groundwater flows in a meso-tidal salt marsh. The model results demonstrate that the subgrid model can be used in a complex salt marsh system with numerous narrow channels, creeks and artificial ditches, with accuracy similar to that of the full model running directly on the high-resolution grid, but computational costs can be two orders of magnitude smaller than for the full grid model. Tidal influence on the phreatic surface of the groundwater in the marsh system was discussed.

中文翻译：

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用于耦合地表水和地下水流的计算高效的子网格模型

摘要 我们提出了一种用于模拟沿海地区地表水和地下水相互作用的高效和高分辨率子网格模型的开发。控制方程是基于完全饱和的地下流假设和相位平均方法推导出来的，其中在子网格水平上分别为地表相和地下相定义了两个相函数。地表水和地下水过程都是通过在粗网格上求解相平均方程来建模的，同时考虑了亚网格效应。实验室数据的模型验证表明子网格模型能够模拟渗透结构内的流动过程。该模型用于模拟中潮汐盐沼中的洪水和排水过程以及地表流和地下水流的相互作用。模型结果表明，亚网格模型可用于具有众多窄河道、小溪和人工沟渠的复杂盐沼系统，精度与直接在高分辨率网格上运行的完整模型相似，但计算成本可能会降低比全网格模型小两个数量级。讨论了潮汐对沼泽系统中地下水潜水面的影响。但计算成本可能比全网格模型小两个数量级。讨论了潮汐对沼泽系统中地下水潜水面的影响。但计算成本可能比全网格模型小两个数量级。讨论了潮汐对沼泽系统中地下水潜水面的影响。