Controls on Well Yields in the Fractured Bedrock Aquifers of Northwestern North Carolina

Northwestern North Carolina is a region of growing seasonal population. Part-time residents populate the region during the summer months, when water levels are typically low. These residents also primarily use groundwater resources pumped from fractured bedrock aquifers as domestic water supply. These aquifers have limited hydrogeologic data and have been historically understudied. A recent drought in this region has prompted the assessment of the local groundwater supply in order to better understand the regional hydrogeology. We analyze correlations between well yield and various topographic and hydrogeologic parameters within the Boone, North Carolina, 7.5-minute quadrangle. We identify these parameters throughout the quadrangle using a GIS environment. We then determine the value of these parameters at 201 wells of known well yield and location (Huffman et al., 2008, USGS Open-File Report 2008-1104). The physical parameters that we examine include bedrock lithology, elevation, well depth, depth to first fracture, sediment thickness, land slope and curvature, distances to the nearest faults, streams, lithologic contacts, lineaments and fracture-correlated lineaments, and upstream drainage area. Analyses of correlations between well yields and each of these parameters suggest that distance to lineaments, distance to fracture-correlated lineaments, and bedrock lithology are the primary predictors of well yield. Elevation, well depth, land slope and curvature, and sediment thickness show no discernable correlation with well yield. Assessing groundwater potential with these methods throughout the region will allow for more effective and sustainable options for development and water use in northwestern North Carolina.