Half-thickness discretized format for simulating compressible delay interbed.

Area of Science:

• Geosciences
• Hydrogeology
• Computational Modeling

Background:

• Ground subsidence modeling relies on simulating compressible interbeds.
• Existing MODFLOW modules (SUB and CSUB) use different approaches (head change vs. geostress variation) for this simulation.
• CSUB's geostress variation method, while more accurate for unconfined aquifers, requires double the computational resources due to full-thickness discretization.

Purpose of the Study:

• To develop a more efficient simulation method for compressible delay interbeds.
• To improve the computational efficiency and reduce memory requirements of geostress-based interbed simulation.
• To validate a proposed half-thickness discretization format for geostress variation.

Main Methods:

• Proposed a half-thickness discretization format based on the linear distribution of geostress in compressible interbeds.
• Validated the method through three test cases with varying parameters (discretization units, interbed thickness, head, hydraulic conductivity).
• Compared the proposed method against the full-thickness discretization of the CSUB module, analyzing computation time and memory usage.

Main Results:

• The proposed half-thickness method achieved high accuracy, with interbed water release differences less than 0.4% compared to the CSUB module.
• Demonstrated significant computational advantages: reduced computation time by 46.23% and memory usage by 13.64%.
• The method leverages the linear geostress distribution for improved efficiency.

Conclusions:

• The proposed half-thickness discretization format under geostress variation offers a highly accurate and computationally efficient alternative.
• This method significantly enhances simulation efficiency and reduces memory demands for modeling compressible interbeds.
• Provides a feasible technical approach for large-scale, high-precision land subsidence modeling.