The feasibility of using tree-ring chronologies to augment hydrologic records in Tasmania, Australia

Abstract

Monthly streamflow records from 8 gauging stations in western Tasmania seasonalized to include either the 5 months, November through March, or the 12 months, April through March, were used as predictands in a series of multiple linear regressions. The predictors were treering eigenvector amplitudes derived from 11 chronologies, representing 4 species, from sites all over the state. Tree-ring widths in both the current and following years were significant in predicting runoff for the November-March period but not for the longer season. Canonical correlations and regressions calculated between the set of 8 runoff records and the set of 11 tree-ring chronologies accounted for 47% of the variance of the 5-month streamflow during the 1958-1973 calibration period. Estimates of seasonalized summer runoff back through 1776 at 8 gauging stations were obtained by applying canonical regression equations to the 198-year tree-ring record. Three of the reconstructed series were verified using runoff data recorded for at least 8 years outside the calibration period. The results of this first attempt to employ tree-ring chronologies to extend streamflow records in Tasmania show promise for more widespread future applications of the technique.