Bent Creek Groundwater Monitoring and Research Station
Buncombe County, NC
The Bent Creek Research Station (BCRS) basin is located within the Blue Ridge geologic belt (fig. 1), in the Ashe Metamorphic Suite, and is characterized by rugged, often steep terrain. The portion of the basin being investigated as part of REP is located within the 1.1 mi2 sub-basin drained by Boyd Branch (figure 2). Boyd Branch is one of 13 perennial 2nd order tributaries to Bent Creek. Elevation at the ridgeline boundary of the Boyd Branch sub-basin is about 3,200 feet above mean sea level, and elevation at the base of the sub-basin, where Boyd Branch discharges into Bent Creek, is about 2,180 feet above mean sea level.
The primary objectives of the hydrogeologic investigation are to: (1) characterize the ground water geochemistry in a pristine, mountain setting underlain by mica schist and evaluate changes over time and space within the local groundwater system; (2) evaluate the hydraulic communication between the shallow regolith and deeper bedrock flow systems and the local flow dynamics between ground and surface water in both recharge and discharge areas; (3) evaluate the regolith-bedrock transition zone and its role as a preferential groundwater flow pathway; (4) characterize aquifer properties in the regolith and bedrock in selected areas; (5) determine the age of groundwater and time of travel from a recharge area to a discharge area; and (6) track water level fluctuations over time, in response to fluctuations in evapotranspiration, rainfall, and seasonal climate.
The BCRS consists of one stream gage, 6 well nests, and 15 piezometers. Each well nest consists of three wells open to different zones within the ground water system: upper regolith, lower regolith, and fractured bedrock. The well nests are spaced 500 to 1500 feet apart along a mile long transect from topographic highs in recharge areas to lows in discharge areas. Numerous tests have been conducted on water quality, ground water movement, and hydrogeologic setting, including standard analytical tests, ground water age dating, oriented borehole geophysical surveys, water level measurements, continuous temperature measurements, 72-hour aquifer tests, and others. The gage, wells, tests, and analyses were used to evaluate ground water availability, movement, and quality in a regolith-fractured rock flow system dominated by mica schist.
NC DENR-DWQ-APS, 2090 U.S. Highway 70, Swannanoa, NC 28778