State Water Resources Research Institute Program

Project ID: 2007OK80B
Title: Determination of Fracture Density in the Arbuckle-Simpson Aquifer from Ground Penetrating Radar (GPR) and Resistivity Data
Project Type: Research
Start Date: 3/01/2007
End Date: 2/28/2008
Congressional District: 3 & 4
Focus Categories: Water Supply, Hydrology, Models
Keywords: Fractures, GPR, Resistivity
Principal Investigators: Cemen, Ibrahim; Halihan, Todd (Oklahoma State University)
Federal Funds: $ 24,987
Non-Federal Matching Funds: $ 49,974
Abstract: The ground water resources of Oklahoma are vital to the economic well being of the state. In order to properly manage these resources, an understanding of the discharge and recharge of aquifers is necessary. Fractures in aquifer rocks affect the flow of water. Therefore, numerical modeling of the fluid flow requires an understanding of the nature of fractures that have a great influence on the discharge and recharge mechanisms. In the State of Oklahoma, the Arbuckle-Simpson aquifer is a major source of drinking water for communities in the south-central part of the state. In outcrops, the carbonate units of the Arbuckle-Simpson are highly fractured. The basement rocks underlying the Arbuckle-Simpson aquifer are also highly fractured in outcrop. For example, the granites exposed in the Devil's Den area near Tishomingo, Oklahoma exhibit extensive fracturing and faulting. The characterization of fractures in the basement is also important for ground water modeling.

The scope of the present project is three-fold. The first phase will begin by identifying fracture patterns and major faults in outcrop. A high resolution 3-D GPR survey will be conducted with 450 MHz transmitter and receiver antennas. In addition, a few 2-D GPR lines will be acquired with the 200 MHz transmitter-receiver antenna pair to determine how well this system works in mapping fractures in comparison to the 450 MHz system. If the results from the 200 MHz system are satisfactory, then a detailed 3-D GPR survey will be conducted with this system because of the greater depth of penetration than the 450 MHz system. The second phase of the project will focus on the acquisition of resistivity data and its interpretation. Initially, only 2-D resistivity lines will be acquired to match the GPR data acquired in Phase 1. The decision to acquire 3-D resistivity data will be made based on our ability to image fractures from this data, and the difficulty of planting electrodes in carbonate rocks of the Arbuckle-Simpson group and the granitic basement. The third phase will include repeat surveys for both GPR and resistivity data acquisition under wet rock conditions. A comparison of the data acquired in dry and wet conditions may help us in determining whether the fractures are open or closed.

The results of this research could be beneficial to the ground water modeling work currently underway at both the Oklahoma Water Resources Board (OWRB) and the United States Geological Survey (USGS). Therefore, mapping fracture density from geophysical data such as Ground Penetrating Radar (GPR) and Resistivity would provide timely information for these modeling studies.

Progress/Completion Report, PDF

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