Palaeohydrology in climatological context: Developing the case for use of remote predictors in Australian streamflow reconstructions

The dry continent of Australia experiences frequent periods of devastating regional drought, making high quality palaeohydrological reconstructions essential for water resource management and planning. In other parts of the world tree-rings form a core component of such reconstructions. Yet for much of Australia, annually resolved palaeohydrological reconstructions derived from tree-rings have proven elusive. The island state of Tasmania in the far south is an important exception, with over 50 tree-ring chronologies available. Coupled ocean-atmosphere processes that drive precipitation across mainland Australia also influence Tasmanian precipitation. Here, we provide a basic analysis of how geographic relationships between important drivers of seasonal Tasmanian streamflow and potential streamflow predictors such as tree-ring chronologies may extend the spatial applicability of Tasmania's tree-ring predictors beyond the local context. We find clear geographically and seasonally defined patterns in Tasmanian streamflow that are reflected in the relationships between individual Tasmanian tree-ring chronologies and their relationships with streamflows. We find strong evidence that quality Tasmanian summer (DJF) streamflow reconstructions based on tree-rings are possible. Evidence also suggests that streamflow reconstructions for other seasons are also likely to be possible, especially as additional chronologies based on wood properties such as tracheid radial diameter, microfibril angle, density and cell wall thickness become available. Based on the relationships between streamflows and tree-ring chronologies, and between streamflows and major precipitation drivers across Australia, we conclude that Tasmanian tree-ring chronologies are likely to prove useful as predictors for seasonal streamflow reconstructions, particularly in eastern Australia. Successful streamflow reconstructions for a much broader portion of Australia than currently available will be invaluable for future water resource management and planning.