ADVANCING KARST HYDROLOGIC UNDERSTANDING THROUGH LONG-TERM MONITORING OF STORM RESPONSES IN A COMPLEX AQUIFER SYSTEM

The Lost River Karst Aquifer (LRKA) system has two sites where long-term monitoring of storm event responses and their associated discharges and hydrogeochemistry provide insight to responses of a continuous telogenetic karst aquifer system with multiple access points for monitoring. Over the past several years, advancement in the monitoring technology and adaptation of it to improved understanding of these systems, including the use of secondary data and additional types of data collection technology now available, has allowed for a deeped investigation of methods by which to calculate drainage basin area and effective recharge in rapidly responding karst systems in both urban and rural settings. Under a changing climate, this is particularly important, due to changes in flood frequency planning, groundwater residence times, and stormwater infrastructure lagging behind the variability of storm events and their associated impacts. Methods include collecing precipitation totals from ASOS, COOP, KYMN, Onset HOBO, and CoCoRAHS weather stations within the same drainage basin, which were compared to discharge totals from Lost River Rise (LRR) and Blue Hole Four (BHF). Data were measured and collected for 32 continuous months, with evapotranspiration being accounted for at the monthly resolution. Statistical analysis was conducted for storm events to determine predictive flood modeling between the primary output (LRR) and the upstream conduit (BHF). So far, a large difference between the drainage basin area calculated for LRR and BH4 exists. The historic discharge rating curves of previous studies at LRR are being examined in depth, so that the current one can be updated and compared to with respect to landuse, data collection resolution, and storm event intensity, as these may also be contributing to a difference. This research, combined with similar investigations underway at other sites, including Crumps Cave, in south-central Kentucky, can be very useful in determining the amount and duration of precipitation during storm events necessary to cause groundwater-induced flash floods and improve predictive models for planning and emergency response.