Five Centuries of Groundwater Elevation in North-Central Florida

Authors: Evan Larson*, University of Wisconsin - Platteville, Thomas C Wilding, University of Wisconsin-Platteville, Thomas Mirti, Suwannee River Water Management District
Topics: Water Resources and Hydrology, Biogeography, Natural Resources
Keywords: groundwater, reconstruction, water resources, longleaf pine, Pinus palustris, Florida
Session Type: Paper
Day: 4/12/2018
Start / End Time: 3:20 PM / 5:00 PM
Room: Grand Ballroom C, Astor, 2nd Floor
Presentation File: No File Uploaded

Tree ring-based hydrologic reconstructions have extended records of water resources in numerous regions of the world and advanced understanding of the drivers of hydrologic variability. Many early reconstructions focused on relatively xeric environments where water was clearly limited for parts of any given year, yet as the science of dendroclimatology matured efforts extended to more mesic environments where recent droughts have amplified concern for water scarcity in areas with growing human populations. Here, we report 1) the enhancement of an existing longleaf pine (Pinus palustris) tree-ring record for Goethe State Forest in north-central Florida and 2) development and analysis of a new reconstruction of groundwater elevation within the Suwanee River Water Management District. The 532-year long tree-ring chronology spans the years 1472–2004 with an overall mean series-intercorrelation of 0.57 and a robust signal beginning in 1490. A principle-components-based regression model from current year and lagged values of earlywood, latewood, and total ring widths explains 55% of the variance in groundwater elevation above sea level when calibrated on instrumental well data that span 1958 to the present. Split calibration indicates a significant weakening of the relationship between tree growth and ground water elevation since the 1990s. The difference between reconstructed and instrumental groundwater elevations during this period correlates significantly with a similar difference in the relationship between instrumental precipitation and groundwater elevation. These results suggest a growing disconnect between groundwater and precipitation and that recent extreme lows in groundwater elevation may be unprecedented in at least the past 500 years.

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