A Paleo Perspective of Alabama and Florida (USA) Interstate Streamflow

Melanie Vines,Emily Elliott,Jonghun Kam,Leigh Terry,Grant Harley,Joni Corbin,Sahar Sadeghi,Matthew Therrell,Glenn Tootle

doi:10.3390/w13050657

Abstract

Seasonal reconstructions of streamflow are valuable because they provide water planners, policy makers, and stakeholders with information on the range and variability of water resources before the observational period. In this study, we used streamflow data from five gages near the Alabama-Florida border and centuries-long tree-ring chronologies to create and analyze seasonal flow reconstructions. Prescreening methods included correlation and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that several regional tree-ring chronologies were significantly correlated (p ≤ 0.05) with March–October streamflow, and stepwise linear regression was used to create the reconstructions. Reconstructions spanned 1203–1985, 1652–1983, 1725–1993, 1867–2011, and 1238–1985 for the Choctawhatchee, Conecuh, Escambia, Perdido, and Pascagoula Rivers, respectively, all of which were statistically skillful (R2 ≥ 0.50). The reconstructions were statistically validated using the following parameters: R2 predicted validation, the sign test, the variance inflation factor (VIF), and the Durbin–Watson (D–W) statistic. The long-term streamflow variability was analyzed for the Choctawhatchee, Conecuh, Escambia, and Perdido Rivers, and the recent (2000s) drought was identified as being the most severe in the instrumental record. The 2000s drought was also identified as being one of the most severe droughts throughout the entire reconstructed paleo-record developed for all five rivers. This information is vital for the consideration of present and future conditions within the system.

Highlights

Introduction published maps and institutional affilTree-ring based reconstructions of streamflow are advantageous to water planners and policy makers because they extend gage records beyond the observational period, which in turn provides a better understanding of the full range of natural flow variability and the associated climatic drivers within the hydrological system
The number of retained Tree-ring chronologies (TRCs) varied by streamflow gage, but out of the original 148 TRCs, 14 TRCs were retained in the Perdido River, 17 were retained in the Choctawhatchee River, were retained in the Escambia River, and were retained in the Choctawhatchee River and Conecuh correlation analyses
variance inflation factor (VIF) values for all models were within the acceptable ranges (1.0–1.2) and the sign test results were insignificant (p ≥ 0.10) for all the calibration models, indicating that the models were balanced with no significant bias

Summary

Introduction

Tree-ring based reconstructions of streamflow are advantageous to water planners and policy makers because they extend gage records beyond the observational period, which in turn provides a better understanding of the full range of natural flow variability and the associated climatic drivers within the hydrological system. To develop a reliable model of past streamflow conditions, the accuracy and length of the streamflow gage records are crucial for both validating and bias correcting the reconstructed values to that of the observed period. Most streamflow gage data for rivers unimpaired by human activity consist of 60 years of data or fewer, which fails to capture the full range of climate variability, limiting the reliability of the overall modeled streamflow. Tree-ring chronologies (TRCs) often date back centuries and are used as a surrogate for iations

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