An examination of methodologies to assess high-resolution noninvasive sensing of near-surface perched water

Author

Joseph Cole Reagan

Date of Award

12-1997

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering Technology

Major Professor

Robert S. Freeland

Committee Members

John T. Ammons, Robert T. Burns

Abstract

Previous studies have proven the rate that pollutants move through the soil is directly related to the rate that water moves through the soil. The rate that water moves through the soil increases under saturated conditions due to increased macropore flow. When an impermeable layer exists in a soil, the downward movement of water is restricted. If a saturated layer of soil exists above an unsaturated layer, a perched water table forms. A perched water table creates saturated conditions and increased macropore flow above the impermeable layer in the soil profile. Therefore, a perched water table may provide a rapid pathway for pollutants to nearby water resources.

Ground Penetrating Radar (GPR) is proposed as a tool that will noninvasively sense underground perched water. The research objectives of this study are to identify a perched water table in a shallow sandy loam soil lying atop sandstone bedrock, and to validate statistically the developed technique with the use of blind tests. Previous exploratory studies at the Environmental Research Tract (Plateau Experiment Station) are built on, refined, and developed to map morphological features that influence subsurface perched water. Perched water produces an area of signal scatter that occurs near the perched water surface within GPR data. Extensive lab processing of the data attempts to apply filtering methods to the data. The filtering processes aspire to divide the data into low and high frequencies, thus better distinguishing the actual perched water table surface and the orientation of this surface (e.g., slope). Blind tests are used to validate the filtering techniques developed in the lab and to ensure a non-biased interpretation. At present, results have not provided a repeatable method that can enhance the perched water surface so that it can be accurately measured.

Recommended Citation

Reagan, Joseph Cole, "An examination of methodologies to assess high-resolution noninvasive sensing of near-surface perched water. " Master's Thesis, University of Tennessee, 1997.
https://trace.tennessee.edu/utk_gradthes/10688