Tree-Ring Reconstructions of Streamflow for the Tennessee Valley

Abstract

This study reports the preliminary results from a statistical screening of tree-ring width records from the International Tree-Ring Data Bank (ITRDB), to evaluate the strength of the hydrological signal, in dendrochronological records from the Tennessee Valley. We used United States Geological Survey (USGS) streamflow data from 11 gages, within the Tennessee Valley, and regional tree-ring chronologies, to analyze the dendroclimatic potential of the region, and create seasonal flow reconstructions. Prescreening methods included correlation, date, and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that large numbers of regional tree-ring chronologies were significantly correlated (p ≤ 0.05) with the May–June–July streamflow. Stepwise linear regression was used to create the May–June–July streamflow reconstructions. Ten of the 12 streamflow stations were considered statistically skillful (R2 ≥ 0.40). Skillful reconstructions ranged from 208 to 301 years in length, and were statistically validated using leave-one-out cross validation, the sign test, and a comparison of the distribution of low flow years. The long-term streamflow variability was analyzed for the Nolichucky, Nantahala, Emory, and South Fork (SF) Holston stations. The reconstructions revealed that while most of the Western United States (U.S.). was experiencing some of its highest flow years during the early 1900s, the Tennessee Valley region was experiencing a very low flow. Results revealed the potential benefit of using tree-ring chronologies to reconstruct hydrological variables in the Southeastern U.S., by demonstrating the ability of proxy-based reconstructions to provide useful data beyond the instrumental record.

Changes in southeastern USA summer precipitation event types using instrumental (1940–2018) and tree-ring (1790–2018) data

“…Pederson et al (2012) reconstructed PDSI for the Apalachicola-Chattahoochee-Flint River Basin to examine early 21st century droughts, finding recent droughts were not atypical. Harley et al (2017) reconstructed streamflow for the Suwanee River in Florida, finding that historic variations exceeded current instrumental values, while Anderson et al (2019) found mixed results when comparing current flow extremes in their longterm reconstructions of rivers in the Tennessee Valley. These studies provide context to examine hydroclimate and demonstrate that current changes are not unusual when placed in a multi-century context.…”

Reconstrucción dendrohidrológica de escurrimientos en la subregión hidrológica Coahuayana, estado de Jalisco

“…La integración de una red de series dendrocronológicas compuesta por diversas especies ha permitido analizar en diversas regiones geográficas del continente la reconstrucción de índices de sequía (Cook et al, 2010;Stahle et al, 2016), índices de ENSO (Stahle et al, 1998) y de flujos en amplias regiones de Norteamérica (Woodhouse et al, 2006;Anderson et al, 2019) y de México (Villanueva et al, 2017;Martínez-Sifuentes et al, 2020). La cronología regional de madera temprana registró una asociación significativa con los volúmenes acumulados del período enero-junio; esto indica que la precipitación ocurrida en las estaciones de invierno, primavera y principios de verano, de la cual dependen los volúmenes escurridos, define el crecimiento de la madera temprana en el occidente de México.…”

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

“…While dendrochronological reconstructions of hydroclimate, including streamflow, have been widely utilized in the western United States (US) due to the arid, moisturelimited environment [6,7,[16][17][18][19][20][21][22][23][24][25][26][27][28], until recently, similar studies have been relatively limited in the southeastern US [3,8,14,[29][30][31][32][33][34]. However, Crockett et al [2] established TRCs to be useful and statistically significant proxies even in the humid subtropical climate of northern Florida.…”