Degree

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

Document Type

Dissertation

Abstract

The Southern Hills aquifer system (SHAS) is the primary source of water in the Capital area of Louisiana. However, the overexploitation of freshwater-bearing aquifers and the presence of two active faults, the BR fault and the DSS fault, have resulted in groundwater depletion, saltwater intrusion, and increased the risk of land surface subsidence. Such critical issues pose substantial threats to groundwater availability and exert detrimental effects on the environment and urban infrastructures. This dissertation presents a comprehensive investigation of the SHAS for recognizing the consequences of groundwater depletion and its potential long-term impacts on groundwater availability and land stability. A mesh generation methodology based on 2.5D centroidal Voronoi tessellations and curve fitting is proposed to construct an unstructured grid that offers great flexibility in specifying grid connections in 3D, captures intricate geometries, and adds high levels of refinement in areas of interest. The proposed methodology is applied to develop a high-resolution groundwater model for the SHAS, serving as a pivotal tool for providing advanced insights into groundwater availability, aquifer sustainability, and spatial depletion across individual aquifers, with implications for current conditions and future projections under different withdrawal scenarios. A groundwater-subsidence model is developed to assess spatiotemporal variations in groundwater flow and subsurface compaction in the SHAS, as well as the associated vertical displacement induced by long-term groundwater pumping. This provides a substantial framework for understanding the key factors contributing to land subsidence. A transport model is developed to investigate salt migration pathways within the “2,000-foot” sand. This study not only significantly advances the understanding of groundwater availability in the SHAS but also forms the basis for robust groundwater management approaches, thereby preserving the sustainability and resilience of vulnerable areas and informing targeted mitigation strategies.

Date

3-28-2025

Committee Chair

Tsai, Frank T.-C.

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