Regional Velocity Variability through Eogenetic Karst: Integrating Data and Lessons from 122 Years of Applied Tracer Testing in the Upper Floridan Aquifer, Florida
Abstract
As an eogenetic karst aquifer, the Upper Floridan Aquifer (UFA) exhibits complex hydrologic, geochemical, and biological processes that vary over a wide-range of spatio-temporal scales. Knowledge of the complex flow paths and velocity variability in the UFA is of increasing economic and environmental concern as management decisions affect the primary drinking water supply for more than 90% of the population in Florida as well as the water source for the largest concentration of freshwater springs in the world. Between 1896-2018, there were at least 61 applied tracer releases, or injections, into the UFA associated with at least 32 distinct studies. A common motivation for these investigations was the characterization of flow paths and estimation of solute transport rates. However, without a single repository for information gained from decades of applied tracer tests within the aquifer, an incomplete synthesis of prior work has left new investigators with a dearth of data from which to classify regions with common transport characteristics or infer the range of transport conditions that exist across the aquifer. After the mean velocities were estimated from reported first tracer arrival times from the collection of studies (12,000 m/d; CV 1.3), 72 breakthrough curves were selected for additional quantitative analysis from six studies. The calculation of zeroth through third empirical temporal moments, as well as the fitting of parameteric distributions to all breakthrough curves demonstrated greater variability in the velocity distribution. Furthermore, when the dataset was compared to subregions of surface water drainage areas, spatial trends in velocities were observed that suggest conduit flow has greater control over transport in some drainage basins than others. This research offers the first integration of data and analysis of the collection of tracer studies for the characterization of transport characteristics at an aquifer scale in the UFA, allowing the description of common transport modes that may be expected across varying spatial scales in other eogentic karst settings. Because few other eogentic karst systems are likely to have a history of dye tracing as extensive as the UFA, this work provides a unique opportunity to gain insights into the velocity controls in similar hydrogeologic settings.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H52A..02W
- Keywords:
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- 1829 Groundwater hydrology;
- HYDROLOGYDE: 1831 Groundwater quality;
- HYDROLOGYDE: 1832 Groundwater transport;
- HYDROLOGYDE: 1880 Water management;
- HYDROLOGY