Date of Graduation

5-2026

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

Befus, Kevin

Committee Member

Blackstock, Joshua

Second Committee Member

Covington, Matthew

Keywords

seepage; Hot Springs National Park; Groundwater Storage

Abstract

In late 2020, excavation for the Highway 5 Bypass in Hot Springs, Arkansas exposed seepage faces along roadcut walls. Groundwater levels at nearby wells decreased by up to 20.9 ft and have remained ~20 ft below pre-construction values on average. This study quantifies changes in storage in the unconfined aquifer within the Hot Springs thermal recharge zone associated with the seepage faces using a numerical groundwater model calibrated to pre-construction head at well ARb4. Model scenarios are used to evaluate whether construction-induced seepage or drought best explains the decrease from late 2020 to early 2021. The numerical groundwater simulation represented the unconfined groundwater system and associated roadcut as a simulated drain placed at the location of the roadcut. The simulation showed decreases in mean annual groundwater storage of 1,741–1,889 ft³ above the 660 ft critical elevation that supports artesian flow in Hot Springs National Park. Heads decreased by 0.1 ft or more across 58% of the model columns, including cells across a topographic divide, implying a persistent, basin-scale response to seepage at the roadcut. Reducing the average of the sinusoidal, i.e., seasonal, recharge input in a drought simulation produced similar declines in simulated well ARb4, but regional hydroclimate observations over the drought simulation period indicated wetter conditions. Findings from this study indicate construction-induced seepage as the cause of the observed groundwater level declines. The study also highlights that limiting land disturbance above critical recharge elevations in the thermal springs recharge zone could mitigate future impacts. Groundwater storage may be permanently depleted because of construction along the Highway 5 Bypass due to interception by the seepage faces along the roadcut.

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