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Flux towers help us understand Perth’s declining watertables

The past 20 years have seen a significant decline in the watertable in Perth’s most important groundwater recharge area. It’s happening not just in Perth: it’s an increasingly common problem in many parts of Australia.

A collaborative team is using TERN infrastructure installed at Gingin, north of Perth, to quantify the recharge and investigate why watertables might be falling, and, if they are, some of the ecological and social consequences.

Less rainfall, more evaporation and increasing demand for groundwater can combine to have dire ecological consequences. In the case of a woodland 90 km north of Perth, this situation has meant a significant decline in the watertable, leading to a substantial increase in tree death in the past two years. Similar stories are unfolding around Australia.

To address this growing problem, a collaborative project from TERN aims to increase our understanding of how climate, water and vegetation are interacting. To do this, those involved in the project will quantify groundwater recharge and surface–atmosphere exchanges of carbon-dioxide, water vapour and energy at the Gingin site.

The project utilises TERN’s OzFlux tower network and the nationwide CosmOz cosmic-ray soil-moisture-monitoring network to gather information on vegetation change, soil water content and soil heat exchange at Gingin. This information is combined with groundwater measurements to improve our understanding of how vegetation changes in response to a change in environmental conditions (called ecophysiology), in particular a changing climate and falling watertables.

Large amounts of data have already been collected and are being processed by the project team based at CSIRO Land and Water in Perth.

Key to the project’s success will be its collaborative nature. Project Site Leader Dr Richard Silberstein of CSIRO says he plans to work with and share data with the WA Department of Water, which is responsible for managing the region’s groundwater, to gain mutually beneficial project outcomes.

‘We are working closely with the Department of Water, and they are very interested in incorporating our data when they become available via the OzFlux Data Portal later this year. Our data and findings will assist the Department of Water in their management of groundwater by improving the region’s estimates of groundwater recharge’, he says.

Richard’s project team is also planning on working with the University of Western Australia’s International Gravity Observatory to assist it in understanding the effects of environmental noise interference on their gravitational radiation detector. Their goal is to improve the accuracy of their studies.

What’s exciting about this project is that it’s contributing to our understanding of changes in groundwater recharge in response to climate change.

Not only is this information vital in Perth’s most important groundwater recharge area, it is also essential for the rest of Australia, and around the world, as our concern over water scarcity increases and we look for improved water-management strategies.

 

OzFlux has a tower at Gingin to measure various gas exchanges between the ground and the atmosphere. The exchanges tell scientists a lot about how plants change in the face of a rapidly changing climate. (Photo courtesy of Trish Lambert)

 

Published in TERN e-Newsletter September 2013

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