Analytic Element Modeling of Steady Interface Flow in Multilayer Aquifers Using AnAqSim

Area of Science:

• Hydrogeology
• Computational modeling
• Water resource management

Background:

• Simulating groundwater flow with sharp fresh-salt interfaces is crucial for coastal aquifer management.
• Existing numerical methods can be computationally intensive and slow for large-scale applications.
• The analytic element method offers a potential alternative for efficient interface modeling.

Purpose of the Study:

• To present and validate the AnAqSim analytic element modeling approach for simulating steady-state, sharp-interface groundwater flow in multilayered aquifer systems.
• To demonstrate the efficiency and applicability of this method for large-scale interface configuration.
• To provide a viable alternative to traditional numerical modeling techniques.

Main Methods:

• Implementation of the analytic element modeling approach in AnAqSim software.
• Utilizing subdomains, multiple layers, and discharge potentials for shallow interface flow.
• Incorporating a transition to a thin fixed minimum fresh water thickness mode for convergence.
• Comparison and validation against SEAWAT and SWI/MODFLOW.

Main Results:

• AnAqSim successfully simulates steady groundwater flow with a sharp fresh-salt interface in 3D aquifer systems.
• The analytic element approach allows for rapid model construction and provides insights into large-scale interface geometry.
• The thin fixed minimum fresh water thickness mode facilitates convergence to a steady interface position.

Conclusions:

• The AnAqSim analytic element method is an efficient and effective tool for simulating sharp-interface groundwater flow in multilayered systems.
• This approach offers advantages in speed and ease of model construction for large-scale hydrogeological investigations.
• The method provides valuable guidance for managing coastal wellfields and understanding freshwater-saline water dynamics.