Publication Date

Fall 2021

Advisor(s) - Committee Chair

Dr. Jason Polk (Director), Dr. Stuart Foster, Dr. Christopher Groves

Degree Program

Department of Earth, Environmental, and Atmospheric Sciences

Degree Type

Master of Science

Abstract

Epikarst systems have complex recharge – discharge processes in telogenetic karst systems, including highly variable storage, flowpaths, and mixing dynamics. This research aimed to characterize the epikarst zone using hydrogen and oxygen isotopic tracers of these processes within south-central Kentucky’s Crumps Cave system located in the Pennyroyal Sinkhole Plain. Data and statistical analyses were applied to highresolution rainfall (RF), lysimeter (10 cm, 20 cm, 30 cm depths), and an epikarst Waterfall 1 (WF1) isotope data collected on a weekly basis between 2011-2018. These data were coupled with WF1 discharge measurements and weather station data collected at Crumps Cave Preserve during that same period.

Rainfall isotopes demonstrated seasonal variability with isotopes becoming depleted during major storm events. A large response in lysimeter isotope values was observed post-hurricane storm event causing more depleted isotopes. Furthermore, lysimeter isotopic values were more depleted with increasing in soil depth, but at times underwent a homogenizing effect. WF1 isotopic values demonstrated a similar effect, with clustering data points on the local meteoric water line (LMWL), thus, indicating a mixing dynamic taking place between the soil and epikarst layer. The recharge dynamics of the epikarst varied based upon storm event (i.e. intensity, amount, longevity, etc.). Many peak rainfall months showed less response at WF1, in comparison, to months with lower rainfall amounts. This could be due to the lag effect of the hydrologic year versus of the epikarst varied based upon storm event (i.e. intensity, amount, longevity, etc.). Many peak rainfall months showed less response at WF1, in comparison, to months with lower rainfall amounts. This could be due to the lag effect of the hydrologic year versus the calendar year of the plot. Implications on contaminant transport are understood to vary based on the agricultural land use and magnitude of the storm event. Intense rain events will allow contaminants to directly infiltrate into the groundwater system through direct pathways, such as cracks and fractures in the surface or bypassing storage by exceeding the storage threshold. This makes a karst system, such as Crumps Cave, more vulnerable to contaminant transport from agricultural landuse, therefore, causing significant water resource issues for the entire watershed. Future implications depend on more research regarding the recharge dynamics of karst systems, but the results from this study provide information needed to improve best management practices for agricultural practices in karst environments.

Disciplines

Geology | Hydrology

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