State Key Laboratory of Simulation and Regulation of Water Cycles in River Basins, China Institute of Water Resources and Hydropower Research, Beijing, 100038, China.
Department of Water Resources, China Institute of Water Resources and Hydropower Research Beijing, 100038, China.
Ground Water. 2021 Jan;59(1):90-99. doi: 10.1111/gwat.13033. Epub 2020 Aug 17.
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.
MODFLOW 是目前应用最广泛的地下水模拟工具之一；然而，除了 LAK3 包之外，缺乏能够与 MODFLOW 耦合的湖泊模块的开发。本研究提出了一种模拟稳态流下湖泊-地下水相互作用的新方法，称为倾斜湖底法 (SLM)。在这种新方法中，垂直方向上的湖底离散化与含水层系统的空间离散化无关，这可能解决湖泊和地下水通常在不同尺度上进行模拟的问题。湖底通过每个湖泊网格单元底部的倾斜来概括，可以分为完全淹没、干燥和部分淹没。SLM 方法考虑了所有的湖泊源汇，建立了一个可以使用牛顿法求解的控制方程。使用 LAK3 用户手册中的修改模型设置进行了基准案例研究。结果表明，当地下水模型顶层有足够数量的层时，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 可能会给出不切实际的结果。此外，SLM 可以更准确地反映模拟的湖泊表面积与湖水深度之间的关系。因此，在模拟湖泊-地下水相互作用时，SLM 方法是 LAK3 包的一种有前途的替代方法。
