Geophysical Surveys at Lake Poinsett Dam, Poinsett County, Arkansas

Lake Poinsett is a 260-hectare (640 acres) lake located on Crowley’s Ridge in northeastern Arkansas, approximately 6 km southeast of Harrisburg, Arkansas within Poinsett County. The lake was built for recreation by the Arkansas Highway Department in 1960 by constructing a roughly 800-meter dam across the southern boundary of the Distress Creek watershed. The dam is currently operated by the Arkansas Game and Fish Commission (AGFC). AGFC and Arkansas Natural Resources Commission (ANRC) plan to drain the lake to allow access for a series of bank stabilization and dam safety improvements. Because none of the original blueprints exist, AGFC asked the U.S. Geological Survey (USGS) to conduct a series of differential global positioning system (GPS) and geophysical surveys to determine the lithologic framework of Lake Poinsett Dam as well as identify any anomalies that might need to be addressed while the dam was being restored. Three geophysical techniques were used in the investigation: (1) electrical resistivity measurements to evaluate the full thickness (~20 m) of the dam and the sediments that form the base of the dam; (2) Frequency Domain Electromagnetic Methods (FDEM) were used to map the clay core and any metallic anomalies of the dam structure; and (3) self-potential (SP) methods were used to map the zones of potential water movement and seepage within the dam. The methodology for the electrical resistivity, FDEM, and GPS surveys are described in Miller and others (2018). The SP method measures the natural voltage created by groundwater as it flows through porous media (Ikard and others, 2012; Ikard and Revil, 2014). The sensitivity of voltage measurements to groundwater flow is attributable to a direct correlation between the electric field at the surface and the hydraulic gradient in the subsurface. Thus, surface SP data are extremely useful for illuminating preferential groundwater flowpaths and seepage-prone areas within earthen dams and levees (Ikard and others, 2014; Ikard and others, 2015). The SP field is quasi-static in time, meaning that the field does not vary naturally in a transient sense over the short time scales of an engineering survey. Spatial variations in the measured field are independent of the physical gradients that generate streaming current flow. At Lake Poinsett Dam, the predominant physical gradient is hydraulic, and hydraulic gradient is regarded as the major contributor to the observed spatial variation in the SP data. This data release contains four types of data: electrical resistivity profiles, FDEM transects, SP profiles, and differential GPS surveys of the data locations and survey area. A data dictionary is included that defines the column headers/attribute information as well as their units.
References
Ikard, S.J., Revil, A., Jardani, A., Woodruff, W.F., Parekh, M., and Mooney, M., 2012, Saline pulse test monitoring with the self-potential method to non-intrusively determine the velocity of the pore water in leaking areas of earth dams and embankments: Water Resources Research 48, 1–17.
Ikard, S.J., and Revil, A., 2014, Self-potential monitoring of a thermal pulse advecting through a preferential flow path: Journal of Hydrology 519, 34–49.
Ikard, S.J., Revil, A., Schmutz, M., Jardani, A., Karaoulis, M., and Mooney, M., 2014, Characterization of focused seepage through an earthfill dam using geoelectrical methods. Groundwater 52(6), 952-964.
Ikard, S.J., Rittgers, J., Revil, A., and Mooney, M., 2015, Geophysical investigation of seepage beneath an earthen dam. Groundwater 53(2), 238-250.
Miller, B.V., Adams, R.F., Payne, J.D., Killion, W.F., and Kress, W.H., 2018, Geophysical Surveys at Bob Kidd Dam, Washington County, Arkansas, 2018: U.S. Geological Survey data release, https://doi.org/XXXXXXXXXXX (In Review).

Tags: arkansas, crowleys-ridge, electrical-resistivity, frequency-domain-electromagnetics, geophysical-survey, gnss-survey, inlandwaters, lake-poinsett, lake-poinsett-state-park, poinsett-county, self-potential, structure, usgs-5b7b23a4e4b0f5d578846073
Organization: Department of the Interior