Hydrochemical Delineation of Spring Recharge in an Urbanized Karst Basin, Central Kentucky

Alan E. Fryar, Benjamin J. Currens, Cristopher S. Alvarez Villa

Research output: Contribution to journalArticlepeer-review

Abstract

Because of well-integrated surface and subsurface drainage in karst terrains, springs can exhibit relatively rapid hydraulic, chemical, and thermal responses to storms. In urbanized karst basins, impervious cover, stream channelization, and utility infrastructure can alter infiltration, provide alternate pathways for subsurface flow, and affect ambient water quality. We combined continuous logging of electrical conductivity (EC) and water temperature with analyses of stable isotopes (deuterium and oxygen-18) to differentiate focused and diffuse recharge in a karst basin in Lexington, Kentucky, during 2018. Logging occurred at the McConnell Springs Blue Hole and a sinkhole that drains to it; isotopes, specific conductance, and temperature were manually monitored at those sites and along two losing stream reaches. Water temperature at McConnell Springs and stable isotope abundances showed seasonal variability. The Blue Hole responded within hours to stormwater infiltration at the sinkhole (∼2.1 km upgradient), with recharge events marked by colder stormwater in winter and warmer stormwater in spring to early autumn. Stable isotopes indicated that sinkhole infiltration was minimally affected by evaporation during periods of ponding (up to 9 days). Spring discharge appeared to represent a mixture of focused and diffuse, partly evaporated recharge, consistent with a simple hydrologic model of rainfall, runoff, and infiltration in the basin. EC spikes at the spring during January–March were consistent with pulses of road salt or brine in runoff or snowmelt. Despite limited monitoring data, results suggest that restoration of the sinkhole and its inlet stream were effective in stormwater management during an unusually wet year.

Original languageEnglish
Pages (from-to)203-216
Number of pages14
JournalEnvironmental and Engineering Geoscience
Volume29
Issue number3
DOIs
StatePublished - Aug 2023

Bibliographical note

Publisher Copyright:
© 2023 Geological Society of America. All rights reserved.

Keywords

  • Hydrogeology
  • Karst
  • Kentucky
  • Non-Point Source Pollution
  • Stable Isotope
  • Stormwater

ASJC Scopus subject areas

  • Environmental Engineering
  • Geotechnical Engineering and Engineering Geology
  • Earth and Planetary Sciences (miscellaneous)

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