[A-HW26] Hydrological processes of surface-groundwater interactions

[AHW26-01] Advancing Sustainable Coastal Groundwater Management with a 3D Coupled HMC Model for Simultaneous Simulation of Seawater Intrusion and Land Subsidence

*Shih-Jung Wang^1,2、Huu-Duc Truong¹ (1.Graduate Institute of Applied Geology, National Central University、2.Department of Earth Sciences, National Central University)

キーワード：Hydraulic-mechanical-chemical model, Multi-processes simulation, Managed aquifer recharge, Sustainable groundwater development

Climate change and groundwater over-exploitation are making coastal aquifers more vulnerable to seawater intrusion (SI) and land subsidence (LS). Various solutions and modeling tools have been developed to support sustainable coastal water management. Numerical modeling is one of the most effective tools for decision-making, providing accurate simulations and accessible insights. However, existing models particularly those focused on SI, LS, submarine groundwater discharge, or solute transport often fail to simulate multiple processes simultaneously and do not adequately account for geological complexity. As a result, even with extensive calibration data, these models may not fully represent realistic behavior while requiring significant resources. Therefore, this study develops a 3D hydraulic-mechanical-chemical (HMC) coupled model that can simultaneously simulate SI and LS while considering material heterogeneity and variable parameterization. The results show that the model effectively simulates SI, LS, and their interactions while being both time and cost-efficient. By incorporating variable material properties, the model provides a more realistic representation of SI and LS behavior, demonstrating that increasing Young’s modulus and decreasing hydraulic conductivity and storativity during groundwater extraction. Testing of managed aquifer recharge (MAR) approaches confirmed their effectiveness in reducing both LS and SI, and the HMC model also highlighted potential risks associated with this approach, as land uplift can occur due to excessive water injection. Based on the initial successes, additional HMC models are being developed and have shown promising results when considering material heterogeneity and integrating additional pollutant transport processes such as nutrient and heavy metal migration. This study expected that the model will provide an optimal tool for developing more effective solutions for the sustainable management of water resources, the environment, and coastal ecosystems.