CHARACTERIZING AQUIFERS IN NATIONAL PARKS USING CONTINUOUS GROUNDWATER-LEVEL RECORDS: A COMPARISON OF THREE UNIQUE GEOLOGIC SETTINGS

Groundwater supports important natural and cultural resources in many parks in the national park system. Observation wells are available where monitoring the status and trend in groundwater quality and quantity is considered important for tracking the overall health of park resources and/or impending threats. Groundwater levels are primarily monitored to identify long-term trends. These data, however, can also be used to better understand the hydraulic response of an aquifer system to various stresses and to differentiate multiple stresses. Continuous measurements collected at hourly or higher frequencies using automated recording instruments are available from wells and water bodies in three unique geologic settings: the Black Hills of South Dakota, the Arbuckle Mountains in south-central Oklahoma, and the western flank of Hualalai Volcano on Hawaii Island. Groundwater forms several underground lakes in Wind Cave, which penetrates the Madison aquifer in Wind Cave National Park in South Dakota. Groundwater discharge from the Arbuckle-Simpson aquifer maintains baseflow to springs and streams in Chickasaw National Recreation Area in Oklahoma. Groundwater discharge from the Keauhou Aquifer System creates estuary-like conditions in the inland and nearshore marine waters of Kaloko-Honokohau National Historical Park in Hawaii. Continuous groundwater-level records from these sites were evaluated using spectral analysis. The data were used to identify aquifer type and the stresses responsible for high-frequency water-level changes. The results of the analyses are compared and the implications for resource management are discussed.