TEMPORAL AND SPATIAL VARIABILITY IN GROUNDWATER FLOW AND CHEMISTRY ALONG THE CUMBERLAND RIVER, ARTEMUS, KENTUCKY

Groundwater availability in the Appalachian region of eastern Kentucky is constrained by physiography and lithology, with low, rugged mountains and narrow valleys developed on fractured clastic bedrock. We are delineating lithostratigraphy, groundwater flow, and water chemistry in the alluvial aquifer along the Cumberland River in Knox County, Kentucky. We seek to understand seasonal variability in groundwater-river interactions and water quality, with the goal of siting one or more water-supply wells on a 580-acre Army National Guard training facility.

Eleven monitoring wells (14.0-44.5 ft below land surface [bls]) were installed by direct push with core collection and hollow-stem auger in December 2016. The top ~ 0.5 ft of each core was composed of loam, underlain by silty clay to fine sandy clay, transitioning to clayey sands or fine to medium sands toward the bottom. Coarser-grained cores were located in the western half of the site, where the floodplain is wider. Hydrometer and sieve analyses on coarser-grained intervals identified samples as moderately well sorted to uniform sand. Hydraulic conductivity values estimated using HydrogeoSieveXL ranged from 3.81-39.9 ft/d across the western half of the site.

Depth to the water table in January, April, and July 2017 ranged from 1.78 (April) to 18.9 (July) ft bls. Groundwater flowed toward the river, with a steeper gradient along the eastern half of the site. Water levels were monitored hourly in two wells located ~170 and ~1,320 ft from the river. Stage data were obtained from gages located 6 mi downstream and 13 mi upstream. The well closer to the river showed five hydraulic gradient reversals associated with stage rises, with the longest gradient reversal lasting 3 days. Responses to stage rises in the well farther from the river were attenuated and dampened.

Groundwater samples collected in January and April 2017 were relatively dilute, acidic, and suboxic, with total solutes < 200 mg/L, pH values < 6.7, and dissolved O₂ < 2 mg/L for most samples. Major-ion facies were predominantly mixed cation-HCO₃. Samples were within EPA drinking water standards, except for Fe and Mn in several wells in the western half of the site. Forthcoming isotope data will provide insight into recharge, discharge, and groundwater mixing. Monitoring will continue through January 2018.