Recharge pathways and rates for a sand aquifer beneath a loess-mantled landscape in western Tennessee, U.S.A

•Investigated recharge to a regional aquifer beneath a loess-mantled landscape.•Vertical infiltration (∼10 mm/yr) beneath upland surfaces.•Annual water-table fluctuations (∼100–200 mm) require additional sources.•Infiltration through sandy stream beds drives lateral groundwater flow.•Recharge is controlled chiefly by lithology even given ample moisture. : Western Tennessee, U.S.A. : Recharge to aquifers that underlie loess and other fine-grained surficial deposits in western Tennessee as well as other areas is commonly impeded resulting in sensitivity in regard to sustainability of groundwater resources. This study investigates the role of preferential pathways of recharge to the regional Memphis aquifer in an area mantled by loess and fine-grained paleosols. : Data gathered through a vadose-zone chloride mass balance analysis and a year of monitoring physical hydrologic, water chemistry, and environmental and applied tracer data within an upland watershed in western Tennessee indicate that recharge to the Memphis aquifer is dominated by lateral recharge of infiltrated stream water sources rather than vertical infiltration through loess-covered uplands. The results from this research challenge prevailing models of recharge to the Memphis aquifer and aquifers mantled by loess or other fine-grained soils in other regions that envision vertical recharge through fine-grained soils to be the dominant recharge mechanism.