The potential for tree ring hydrologic reconstructions in Australia - what does the future hold?

Understanding how rainfall and streamflow have varied in the past is key to placing recent and future events in context, however it is unlikely that the short instrumental record captures the full range of natural climate, or accurately represents return periods of extreme events (i.e. floods and droughts). As planning and allocation of water is most often based on probabilities of historical events reoccurring, the brevity of the instrumental records in Australia represents a crucial issue for the local water industry. However, proxy records from natural archives of climate (e.g. tree rings, corals, ice cores, speleothems and lake sediments) can be used to extend the hydrological record. While tree rings in particular have provided invaluable information at the catchment scale in regions such as North America, dendrochronology has not been widely applied in hydroclimatological analyses in Australia. This is partially due to the perceived lack of long-lived Australian species with annual rings that can be cross-dated. However, recent advances in the field have identified new species that may be suitable for dendrochronology if alternative structural parameters such as wood density, cell diameters and stable isotope analysis are used to identify annual growth and to develop chronologies. This paper aims to highlight the significant potential for expansion of dendroclimatological research and its application in Australia. To achieve this, we present a new ∼1000-year summer inflow reconstruction for Lake Burbury in western Tasmania, which exhibits significant centennial scale variability. We then develop a Source model that represents the Lake Burbury hydro-electric water supply system to explore the implications of 'alternate hydrological histories' derived from the inflow reconstruction. Importantly, our findings place recent reduced inflows in a long-term context and demonstrate the potential for sequences of flow, spill rate and storage level recovery outside the observed record. Finally, we map locations with significant potential for new chronologies to be developed. This information could be used as a roadmap for future research and proxy data development.