MODFLOW is one of the most popular groundwater simulation tools available; however, the development of lake modules that can be coupled with MODFLOW is lacking apart from the LAK3 package. This study proposes a new approach for simulating lake‐groundwater interaction under steady‐state flow, referred to as the sloping lakebed method (SLM). In this new approach, discretization of the lakebed in the vertical direction is independent of the spatial discretization of the aquifer system, which can potentially solve the problem that the lake and groundwater are usually simulated at different scales. The lakebed is generalized by a slant at the bottom of each lake grid cell, which can be classified as fully submerged, dry, and partly submerged. The SLM method accounts for all lake sources and sinks, establishing a governing equation that can be solved using Newton's method. A benchmarking case study was conducted using a modified model setup in the LAK3 user manual. It was found that when there is a sufficient number of layers at the top of the groundwater model, SLM simulates an almost identical groundwater head as the LAK3‐based model; when the number of layers decreases, SLM is unaffected while LAK3 may be at a risk of giving unrealistic results. Additionally, the SLM can reflect the relationship between the simulated lake surface area and lake water depth more accurately. Therefore, the SLM method is a promising alternative to the LAK3 package when simulating lake‐groundwater interaction.

中文翻译：

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稳态流下湖水相互作用的模拟。

MODFLOW是目前可用的最受欢迎的地下水模拟工具之一。但是，除了LAK3封装以外，缺少可与MODFLOW耦合的色淀模块的开发。这项研究提出了模拟湖泊的新方法-稳态流下的地下水相互作用，称为倾斜湖床法（SLM）。在这种新方法中，垂直方向上的湖床离散化与含水层系统的空间离散化无关，这可以潜在地解决通常模拟湖泊和地下水规模不同的问题。湖床在每个湖网格单元的底部都有一个倾斜，可以分为完全淹没，干燥和部分淹没。SLM方法考虑了所有湖泊源和汇，建立了可以使用牛顿法求解的控制方程。使用LAK3用户手册中的修改后的模型设置进行了基准案例研究。结果发现，当地下水模型顶部的层数足够多时，SLM模拟的地下水位几乎与基于LAK3的模型相同；当层数减少时，SLM不受影响，而LAK3可能会产生不切实际的结果。此外，SLM可以更准确地反映模拟的湖泊表面积和湖泊水深之间的关系。因此，在模拟湖泊时，SLM方法是LAK3软件包的有希望的替代方法-地下水相互作用。