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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #407108

Research Project: Computational Tools and Decision Support System Technologies for Agricultural Watershed Physical Processes, Water Quality and Ground Water Management

Location: Watershed Physical Processes Research

Title: A three-dimensional numerical model for variably saturated groundwater flow using meshless weak-strong form method

item FANG, JIAYU - University Of Mississippi
item AL-HAMDAN, MOHAMMAD - University Of Mississippi
item O'Reilly, Andrew - Andy
item OZEREN, YAVUZ - University Of Mississippi
item RIGBY, JAMES - Us Geological Survey (USGS)

Submitted to: Environmental Modelling & Software
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2024
Publication Date: 2/17/2024
Citation: Fang, J., Al-Hamdan, M.Z., O'Reilly, A.M., Ozeren, Y., Rigby, J.R. 2024. A three-dimensional numerical model for variably saturated groundwater flow using meshless weak-strong form method. Environmental Modelling & Software. 175:1-22.

Interpretive Summary: Physics-based numerical groundwater models can serve as valuable decision-support tools for groundwater resources management, but their application can be difficult in settings with complex geometry such as a meandering river in an alluvial valley. Traditionally, models under these conditions require development of a complex computational mesh, which is an array of points representing geographic locations at regular intervals where the model is applied. Meshless models have recently been developed, but current meshless numerical groundwater models are limited because they do not allow simulation of pumping in an aquifer where the sediments can become unsaturated. Therefore, a new three-dimensional model, CCHE3D-GW-Meshless, has been developed that eliminates the difficult mesh generation process by using a state-of-the-art meshless method while also simulating both pumping and variably saturated groundwater flow. The new model was applied to the Mississippi River Valley alluvial aquifer at an experimental groundwater pumping and injection operation at Shellmound, Mississippi, USA, located adjacent to a meandering river. The model accurately simulated observed groundwater levels. By using this meshless model, the cumbersome and time-consuming mesh generation process can be avoided.

Technical Abstract: Mesh generation for complex real-world topographies can be troublesome for traditional mesh-based numerical models. Meshless numerical methods have therefore attracted much attention. Current meshless numerical groundwater (GW) models either focus on only pumping in the fully saturated zone or merely simulate the variably saturated GW flow without pumping. However, these two components are both essential for a GW model to represent practical real-world conditions. This gap is bridged in this study by developing a three-dimensional model, CCHE3D-GW-Meshless, using the meshless weak-strong form method. CCHE3D-GW-Meshless was verified with three representative cases. Good agreement between the simulation results from CCHE3D-GW-Meshless and the analytical/numerical solutions was found in all verification cases. CCHE3D-GW-Meshless was then applied to a field case of a pumping well near a meandering river located at Shellmound, Mississippi, USA. The hydrological properties of the site were obtained through the calibration of CCHE3D-GW-Meshless, indicating the applicability of CCHE3D-GW-Meshless to real-world problems.