Understanding hydrological flow in karst to improve paleoclimate modelling of speleothems in SE Australia

Paleoclimate studies are an important tool to aid our current knowledge and understanding of past climatic conditions. This in turn can be used to make informed predictions about future climate change and improve natural resource management. In the last decade, paleoclimate research using speleothems has increased. Methods have been established and it has been demonstrated that they may be applied to successfully reconstruct paleoclimate records from stalagmites (Tan et. Al., 2003; Treble et. Al., 2003; Trouvet et. Al., 2009; Jex et. Al., 2011). A key parameter in the successful reconstruction of speleothem-based paleoclimate archives is the understanding of the karst hydrology influencing drip water that leads to calcite deposition (Baldini et. Al., 2006). The typically non-linear relationship between surface recharge and drip water response is highly complex and not yet fully understood (Baker and Brunson, 2003). For example McDonald et. Al. (2007) demonstrated that drips which responded simultaneously to recharge events still exhibited different delivery mechanisms and in turn exhibited discharge responses. To improve speleothems as a climate proxy, long term cave monitoring in two hydrologically different field sites in SE Australia (Wellington and Yarrangobilly caves) is being conducted. Drip water hydrology over a variety of flow regimes was characterised using over 30 drip water loggers. Distinct flow regimes and spatial variability were observed, indicating that drip waters experienced a wide variety of flow paths. It was evident that even over small spatial variations; surface to groundwater connectivity was considerably heterogeneous. To enhance the drip water study, a novel application was introduced to the cave monitoring program which used micro-temperature loggers to monitor heat signals in drip waters. This study is still in its infancy but has the potential to enhance current monitoring programs and produce greater information regarding flow regimes in speleothem formation