Simulation of Lake-Groundwater Interaction under Steady-State Flow

Area of Science:

• Hydrogeology
• Environmental Modeling

Background:

• Groundwater simulation tools like MODFLOW often lack comprehensive lake modules.
• Existing lake packages, such as LAK3, may face challenges simulating lake-groundwater interactions at different scales.

Purpose of the Study:

• To introduce a novel method, the sloping lakebed method (SLM), for simulating steady-state lake-groundwater interaction.
• To address limitations in scale discretization between lake and aquifer systems.
• To provide a robust alternative to the LAK3 package.

Main Methods:

• Developed the sloping lakebed method (SLM) with vertical lakebed discretization independent of aquifer discretization.
• Generalized the lakebed using a slant within each lake grid cell (fully submerged, dry, partly submerged).
• Established a governing equation solvable by Newton's method, accounting for all lake sources and sinks.

Main Results:

• Benchmarking demonstrated that SLM closely matches LAK3 results with sufficient model layers.
• SLM showed resilience to decreasing model layers, unlike LAK3 which risked unrealistic outputs.
• SLM more accurately reflects the relationship between simulated lake surface area and water depth.

Conclusions:

• The sloping lakebed method (SLM) is a promising alternative for simulating lake-groundwater interactions.
• SLM offers improved accuracy and stability compared to the LAK3 package, particularly in handling scale differences.
• SLM provides a more reliable approach for hydrological modeling involving lakes and aquifers.