Wellington Caves as natural laboratories for groundwater and climate research

Posted 10 June 2010

Stalagmites and stalactites

UNSW has commenced a major new research initiative investigating how to obtain more accurate records of past climatic and environmental change from the mineral deposits that form in caves.

The new project at Wellington Caves, NSW, takes advantage of the nearby National Centre for Groundwater Research and Training (NCGRT) teaching and research facility, and groundwater and surface climate monitoring facilities supported by funds from the Federal Government Groundwater Environmental Infrastructure Fund (EIF).

Stalagmites and stalactites found within limestone caves can be viewed as 'time capsules' that preserve records of the past. Formed from the mineral calcium carbonate, they can contain evidence of surface and cave climate as well as the overlying soil and vegetation and can be precisely dated using the decay of naturally occurring isotopes of uranium. Stalagmites, stalactites and other carbonate mineral formations found in caves are collectively known as speleothems (meaning 'cave deposits').

Speleothems grow over time from groundwater percolating into the parts of caves that are above the water table (in the unsaturated zone of an aquifer).

Because the growth of speleothems is directly linked to the groundwater supply, and this supply is influenced by climate and environmental changes that affect the rate of groundwater flow over time and the nature of the groundwater flow path into the cave, speleothems can provide a record of changes in climatic and environment conditions during the time periods when they formed.

Additionally, fluctuations in the water table over time may flood the caves and stop speleothems growing. It is possible to determine when these changes in water table occurred in the past by dating the timing of speleothem growth before and after these events.

The effects of groundwater flow paths into caves are poorly understood at present and are the focus of the current research that uses caves as 'natural laboratories' to investigate the properties of groundwater percolating into them.

At the Wellington Caves, UNSW researchers have for the first time installed a large number of state-of-the-art loggers that automatically measure the water flow rates from stalagmite-forming drip waters. This will allow them to quantify the variability of the flow and relate it to properties of the aquifer such as sedimentary structure and fracturing of the surrounding rock, as well as local and regional groundwater levels measured in flooded cave passages and boreholes.

This in turn will allow researchers to better understand the how to use the information obtained from stalagmites to interpret past changes in climate and vegetation, and to evaluate how well speleothems record groundwater variability.

The research team includes CWI staff Professor Andy Baker, Professor Ian Acworth, Dr Martin Andersen and Dr Matt McCabe; as well as research students and visiting researchers. Catherine Cockburn (MSc Hydrogeology) is investigating the sources of rainfall reaching the Wellington Region and PhD student Cecilia Azcurra is refining a limestone unsaturated zone isotope hydrology model in collaboration with visiting researcher Dr Chris Bradley (University of Birmingham, UK).

Links:

Latest news

Ancient water to drain from farmland without ongoing joint management

Ancient water to drain from farmland without ongoing joint management

1 July 2020

The management of withdrawals of ground water in the Central West remains an area of hotly-contested debate. Associate Professor of Hydrogeology Bryce Kelly has spent over a decade studying groundwater in the Central West, and has credited groundwater with “saving rural communities from collapse”, but its potential for future drought-proofing depends on how successfully it’s managed. He says current withdrawals “will only be sustainable if the Narromine region gets flooded frequently enough to balance the volume of groundwater extracted."

Read more…

GWI Global Water Matters Podcast

21 June 2020

The UNSW-GWI Global Water Matters Podcast was launched in 2020 to share interesting and important water-related developments and insights from global experts across the broad spectrum of water-related disciplines. Born from the demand to continue the Water Issues Commentary seminar series under the constraints of social distancing, new episodes are released monthly.

Read more…

The mystery of Thirlmere Lakes

The mystery of Thirlmere Lakes

22 May 2020

During the past decade, water levels in the Thirlmere Lakes have varied from full in 2016 to completely dry between October 2018 and February 2020. These variations have raised concerns with the local community and left them wondering; "Where has all the water gone in Thirlmere Lakes?"

Thirlmere Lakes National Park, located south-west of Sydney in an ancient river meander, contains five lakes – Lake Gandangarra, Lake Werri Berri, Lake Couridjah, Lake Baraba, and Lake Nerrigorang. 

Two WRL research teams (EcoEng and Connected Waters) have investigated the water balance budget and surface-groundwater interaction in Thirlmere Lakes. These investigations were supported by coordinated research projects with ANSTOUniversity of Wollongong, and the NSW Department of Planning, Industry and the Environment (DPIE). In collaboration with these groups, WRL engineers undertook extensive fieldwork between 2017 and 2020 to monitor the site, including remote sensing bathymetry surveys, deploying micro-meteorological stations for measuring evapotranspiration, and installing a piezometer network for groundwater investigations.

Read more about the research findings here.  


Read more…

Subsidies drive Murray-Darling Basin extractions as environment loses

Subsidies drive Murray-Darling Basin extractions as environment loses

21 May 2020

Subsidised irrigators extracted up to 28 per cent more water than those who received no funds under a national Murray-Darling Basin irrigation efficiency program, a new study has found.

Read more…

Groundwater resources in Africa resilient to climate change

Groundwater resources in Africa resilient to climate change

8 August 2019

Groundwater – a vital source of water for drinking and irrigation across sub-Saharan Africa – is resilient to climate variability and change, according to a new study.

Read more…