Monitoring infiltration water at Yarrangobilly Caves, NSW: implications for past recharge and speleothem paleoclimate reconstructions

Markowska, M; Treble, PC; Baker, AA; Andersen, MS

Monitoring infiltration water at Yarrangobilly Caves, NSW: implications for past recharge and speleothem paleoclimate reconstructions

Date

2013-09-20

Authors

Publisher

International Association of Hydrogeologists

Abstract

The Snowy Mountains region in New South Wales Australia is an area of national significance as it provides critical head waters for many important water courses, such as ~29% of the Murray River. Recently, this area has been identified as vulnerable to future climate change (Australian Alps National Parks, 2012), thus a better understanding of past recharge and baseline climate variability is highly desirable. This study presents an investigation of the modern karst hydrology at Yarrangobilly Caves, ~70 km from Tumut, NSW. Utilising caves as a natural observatory we can determine 1) vadose-zone flow regimes, and 2) when recharge occurs at Yarrangobilly. This information can improve our understanding of recharge at the site, and also serve as a means of identifying suitable speleothems in caves to reconstruct past climate and recharge variability, at least over the last few thousand years of similar mean climate state. A high-frequency, spatially-dense drip water monitoring campaign in Harrie Wood Cave, Yarrangobilly, was conducted over an 11 month period to characterise the flow regimes of 14 sites within the cave. Sites were monitored using acoustic drip loggers and temperature sensors recording at 15 minute intervals. This monitoring study revealed a moderate relationship between decreasing drip rates and increasing depth (r2 = 0.40), however discharge was still highly variable between sites. Complex controls unrelated to depth, such as unsaturated zone storage and mixing, appear to have a significant impact on vadose-zone flow regimes. This was evident in a hydrograph analysis comparing the drip response between sites to specific effective rainfall events, revealing differences in base flows, lag times and response magnitude. These findings may be applicable to other karst areas with mature limestones of low primary porosity and may also have important implications for the choice of speleothem material used for reconstructing past climate.

Description

Australian Alps National Parks. 2012. “ Water catchment in the Australia Alps". Department of Sustainability, Environment, Water, Populations and Communities. Canberra. Accessed 27/06/2012 http://www.australianalps.environment.gov.au/learn/pubs/water.pdf

Keywords

Water influx, Caves, Climatic change, Rivers, New South Wales, Australia, Hydrology, Rain, Alps, Paleoclimatology

Citation

Markowska, M., Treble, P., Baker, A., & Andersen, M. S. (2013). Monitoring infiltration water at Yarrangobilly Caves, NSW: Implications for past recharge and speleothem paleoclimate reconstructions. Paper presented to the IAH 2013, Perth, Australia : "Solving the groundwater challenges of the 21st century", International Association of Hydrogeologists, 40th International Conference, Perth, Western Australia, 15-20 September 2013, (pp. 205).