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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGEMENT AND TREATMENT OF DRAINAGE WATERS FOR WATER QUALITY PROTECTION AND SUSTAINABILITY OF AGRICULTURAL PRODUCTION IN THE MIDWEST U.S. Title: A Gpr Agricultural Drainage Pipe Detection Case Study: Effects of Antenna Orientation Relative to Drainage Pipe Directional Trend

Author
item Allred, Barry

Submitted to: Journal of Environmental & Engineering Geophysics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 18, 2012
Publication Date: March 1, 2013
Repository URL: http://handle.nal.usda.gov/10113/58170
Citation: Allred, B.J. 2013. A GPR agricultural drainage pipe detection case study: Effects of antenna orientation relative to drainage pipe directional trend. Journal of Environmental & Engineering Geophysics. 18(1):55-69.

Interpretive Summary: Locating buried drainage pipes is a difficult task confronting farmers and land improvement contractors, especially in the Midwest U.S., where the removal of excess soil water using subsurface drainage systems is a common farm practice. Previous research supports the feasibility of using ground penetrating radar (GPR) to find buried agricultural drainage pipes. One aspect of GPR drainage pipe location and assessment needing further investigation is the response associated with GPR antenna orientation either perpendicular or parallel to drain lines.Results from this study show that antennas aligned perpendicular to the drain lines provide the strongest GPR drainage pipe response for agricultural field conditions with moderately dry soils and empty, air-filled drainage pipes, such as would be present during periods of limited rainfall and high drying rates.Antennas parallel to the drain lines provide the strongest GPR drainage pipe response for agricultural field conditions with wet soils and water-filled or partially filled drainage pipes, such as would occur during, directly following, and a few hours or days shortly after large rainfall events. This information will improve the efficiency and success of investigations designed to locate drainage pipes.

Technical Abstract: Locating buried drainage pipes is a difficult task confronting farmers and land improvement contractors, especially in the Midwest U.S., where the removal of excess soil water using subsurface drainage systems is a common farm practice. Enhancing the efficiency of soil water removal on land containing a functioning subsurface drainage system typically involves installing new drain lines between the old ones. Before this approach can be attempted, the older drain lines have to be mapped. Previous research supports the feasibility of using ground penetrating radar (GPR) to find buried agricultural drainage pipes. However, one aspect of GPR drainage pipe location and assessment needing further investigation are the GPR pipe response effects associated with GPR antenna orientation relative to drainage pipe directional trend. Therefore, a field research study was carried out at a specially designed test plot to evaluate the effect on GPR drainage pipe detection due to the antenna-to-pipe orientation. Antenna orientations perpendicular and parallel to drain lines were tested using 250 MHz antennas. The GPR data was collected under moderately dry and very wet soil conditions. Overall study results indicate that there can be substantial differences in the strength of the GPR drainage pipe response for an antenna orientation perpendicular to a drain line versus an antenna orientation parallel to a drain line. Under moderately dry soil conditions, a GPR antenna orientation perpendicular to the drain line provides the best GPR drainage pipe response. Conversely, under very wet soil conditions, a GPR antenna orientation parallel to a drain line provides the best GPR drainage pipe response. Consequently, these findings indicate that on-site assessment of soil moisture conditions and knowledge of general drain line directional trend can be employed with the GPR system antenna set-up and formulation of a GPR survey plan to improve GPR drainage pipe detection and assessment capabilities.

Last Modified: 12/19/2014
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