Semester of Graduation

Fall 2025

Degree

Master of Science (MS)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

The Texas Coastal Lowlands Aquifer System (CLAS) is a crucial water resource for the Gulf Coast, serving millions through municipal, agricultural, and industrial supplies. However, its sustainability is increasingly threatened by factors such as population growth, saltwater intrusion, land subsidence, and climate change. A significant limitation is the absence of a comprehensive, data-rich, three-dimensional lithologic model that accurately represents the intricate structure and geometry of the aquifer. Existing models are overly simplistic, treating the hydrogeologic unit as laterally uniform and failing to capture its true hydrogeologic complexity. This study addresses this gap by developing the first high-resolution 3D lithologic model of the CLAS, integrating approximately 146,000 well logs using the existing proposed Horizon-assisted Lithologic Modeling (HALM) and natural neighbor interpolation. The resulting hydrogeologic framework provides, for the first time, an accurate 3D delineation of the five principal hydrogeologic units, capturing the distinct geometry of each unit with structurally consistent realism. It also effectively delineates the large-scale folding in the southern CLAS, accurately capturing a structural feature that had not been represented in previous models. Model validation through blind well cross-validation confirmed its reliability for groundwater flow simulation, recharge mapping, and vulnerability assessment. The hydrostratigraphic model of the dip-oriented cross-sections also identified key recharge zones and preferential groundwater flow pathways. Beyond regional utility, this methodology offers a transferable framework for characterizing complex coastal aquifers worldwide, as demonstrated in the Texas CLAS, and provides a critical foundation for groundwater resource planning in an era of increasing environmental stress.

Date

11-3-2025

Committee Chair

Tsai, Frank

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