Earth and Atmospheric Sciences, Department of
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
First Advisor
Irina Filina
Committee Members
Erin Haacker, Doug Hallum, Jesse Korus
Date of this Version
8-2025
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Earth and Atmospheric Sciences
Under the supervision of Professor Irina Filina
Lincoln, Nebraska, August 2025
Abstract
Groundwater is an important resource in the state of Nebraska for supporting industries and ecosystems. Monitoring this vast resource ensures its continued availability for generations to come. However, monitoring utilizes well data, and if a well is not present in a desired location, geophysical methods can be explored. This project tests the capability of repeated gravity surveys over Nebraska’s aquifers to monitor groundwater levels throughout 2024.
Two study areas were selected in Eastern Nebraska. The first is in Oakland, Nebraska, over a confined aquifer system. The second is in Plymouth, Nebraska, and exhibits unconfined conditions. Four sites were chosen to collect data in the Oakland study area, and only one in Plymouth, each with an observation well for comparison with the gravity data. Data collection began in April 2024 with measurements once a month during the recovery seasons (April-May, October-December), and twice a month during the irrigation period (June-September).
The results from the Plymouth survey show a strong correlation between the change in gravity and the groundwater level variations in the well (R = 0.75), which is consistent with the unconfined conditions of the aquifer. In addition, specific yield in a range of 25% to 29% was estimated for the aquifer, which aligns with published estimates for the area (20-25%). In Oakland, all four surveys exhibit similar trends in gravity. However, two sites show no correlation (R = -0.05) with gravity readings, which is expected for confined aquifer settings. The other two show a moderate correlation (R = 0.56) which suggest either a nearby recharge area or a leaky confined aquifer for these sites. This project also summarizes recommended guidelines for future gravity surveys, which are beneficial to further develop this methodology over unconfined aquifers in Nebraska. Overall, gravity surveying proved efficient for monitoring local aquifers in unconfined settings.
Advisor: Irina Filina
Comments
Copyright 2025, Kaitlin M. Steinauer. Used by permission