Graduation Term

Summer 2026

Degree Name

Master of Science (MS)

Department

Department of Geography, Geology, and the Environment

Committee Chair

Wondwosen Seyoum

Committee Member

Eric Peterson

Committee Member

Lisa Tranel

Abstract

The Mahomet Aquifer is a vital groundwater resource in east-central Illinois, supporting municipal, agricultural, and industrial water use. With projected changes in water demand driven by population growth and future socioeconomic conditions, assessing the long-term response of the aquifer is critical for sustainable groundwater management. Increased pumping to meet future demand may contribute to groundwater-level decline, intensified cones of depression, and altered groundwater-flow paths relevant to contaminant migration. This study addressed two research questions: (1) how projected changes in groundwater demand affect groundwater levels in the Mahomet Aquifer, and (2) how projected demand influences groundwater-flow paths relevant to contaminant migration. To address these questions, steady-state, three-dimensional numerical groundwater-flow model of the Mahomet Aquifer was developed using MODFLOW-NWT and calibrated to observed groundwater-level data for the year 2005. Projected groundwater-demand scenarios for 2030 and 2050 were developed from Shared Socioeconomic Pathway-based forcing scenarios and applied to the model to evaluate future groundwater response. Particle tracking using MODPATH was then used to assess changes in advective groundwater-flow paths and capture behavior under projected pumping conditions. The calibrated model reasonably reproduced the observed hydraulic head distribution, with a root-mean-square error (RMSE) of 4.01 m and an R² of 0.95. The validation results yielded an RMSE of 3.77 m and an R² of 0.97. Model results indicate that all future demand scenarios produced greater drawdown than the historical 2005 pumping condition, with maximum simulated drawdown ranging from 11 to 21 m. The strongest groundwater-level declines remained concentrated around existing pumping centers, while the spatial footprint of drawdown expanded under future demand growth. In general, the 2050 scenarios produced stronger and more extensive drawdowns than the corresponding 2030 scenarios, and among the evaluated scenarios, SSP2-4.5 in 2050 produced the strongest overall groundwater-level response. Sensitivity analysis showed that recharge and hydraulic conductivity of the Mahomet Aquifer were the dominant controls on simulated hydraulic heads. Particle-tracking results further indicated that projected demand growth increased local hydraulic control near pumping centers. These findings provide insight into balancing groundwater extraction while mitigating contamination risks. By integrating groundwater modeling with climate and socioeconomic projections, this study provides a useful framework for developing adaptive management strategies to support the long-term reliability and quality of the Mahomet Aquifer as a water resource in east-central Illinois.

Access Type

Thesis-Open Access

Download

Share

COinS