Masters Theses

Date of Award

12-2001

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering Technology

Major Professor

Robert S. Freeland

Committee Members

Ronald E. Yoder, John T. Ammons

Abstract

With increasing technological advances in subsurface surveying and geographical positioning, the ability to efficiently and accurately produce maps of subsurface features is a reality. The use of technological equipment is expensive, but surveying costs can be reduced by enhancing the advantages and utility of the equipment. In particular, technological advances in geophysical equipment are leading to efficient protocols in subsurface data acquisition. In order to effectively map and analyze data, especially in a geographically referenced environment, exact geographical positions of sample data must be obtained. With the widespread availability and dropping costs of differential global positioning systems (DGPS), commercial and institutional fields alike are turning to this surface surveying technology for a variety of applications. Coupling geophysical instrumentation with DGPS technology extends the limits of subsurface surveying accuracy and efficiency.

When compared to traditional intrusive techniques like soil-core analysis and well monitoring networks, geophysical instrumentation, especially non-intrusive instrumentation, has the ability to collect more samples, over the same area, and in the same amount of time. Increasing the efficiency of geophysical surveying with mobility and maintaining data integrity yields accurate results and better management decisions. Preservation of existing environmental conditions is inherent to non-intrusive geophysical surveys. This is especially important for cases in which temporal observations have to be made on the same landscape and repeated ground disturbances could affect natural processes like groundwater flow. One disadvantage inherent to geophysical equipment is the introduction of error caused by interference from a variety of sources, both natural and anthropogenic.

Focusing on the advantages of non-intrusive geophysical surveying, this study provides a description and analysis for the utility of two mobile survey systems utilizing electromagnetic induction (EMI) and ground-penetrating radar (GPR). Mobility of both systems was possible with the use of an all-terrain utility vehicle. The vehicle was used to tow an instrument cart while operating the mobile EMI survey system and an antenna skid while operating the mobile GPR survey system. The objective of this study was to provide increased survey area coverage using EMI and GPR with no loss in survey accuracy. Interference and efficiency studies were conducted on the mobile EMI survey system and the mobile GPR survey system. Results of these tests indicate nominal interference from the system components. Efficiency studies were also conducted on both survey systems. These tests indicate that both systems are highly effective for rapidly acquiring geographically referenced subsurface feature data. In fact, data show that the mobile EMI survey system is 100 times faster than a traditional manual survey and the mobile GPR survey system reduced data-acquisition and post-processing times by half. The final product in both systems is the ability to produce subsurface feature maps in a GIS environment. For both systems, the final mapping utilizing data from the mobile survey system was found to be more efficient than mapping with data acquired using traditional techniques. In fact, data from this study suggest the mobile GPR survey method is 400% more efficient in GIS integration and mapping.

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