THE CORRELATION AND DISTORTION BETWEEN ELECTRICAL RESISTIVITY DATA AND TRADITIONAL METHODS OF MAPPING AND MEASURING CAVES AT THE UPPER GREEN RIVER BIOLOGICAL PRESERVE

The Upper Green River Biological Preserve is located in western Kentucky, about 4 miles northeast of the Mammoth Cave National Park boundary, there are multiple caves that have not yet been studied or even viewed by human eyes. Two students were sent into one of these caves to sketch and take measurements in a more traditional fashion. An Electrical Resistivity array was conducted on the small cave to produce a 3-D model showing the cave in the subsurface. An objective of the project was to compare and correlate the data gathered and modeled from the Electrical Resistivity array and the traditional method of mapping a cave and then depicting the cave through sketches. The main objective was to determine if there is any sort of distortion between the 3-D model and the traditional styles.

The array used was a 55 foot by 25 foot rectangle with 5 foot spacing between electrodes. A total of 72 electrodes were used and allowed for approximately 16.5 feet of depth. This allowed for the modeling of the full cave along with adequate resolution. The resolution is determined by taking half of the spacing between electrodes. With the 5 foot spacing, we achieved approximately 2.5 feet of resolution. EarthImager 3D was then utilized to model the resistivity data collected.

The data that was collected from both data sets is comparable and was correlated. It was found that there is a minor amount of distortion between the 3-D model and the sketches. This could result from a multitude of factors: one could be due to the vegetation and rock on the surface. Due to this, some of the array lines were not fully straight and could have led to the distortion. In addition to the surface variations, we were unaware of how the cave conduits traveled underground. Future work for this project is in the planning stages. Another array is being designed to assist with the determination of the amount of distortion between the methods.