Willunga

Infrastructure at the Willunga site focusses in five main areas: surface water – groundwater interaction; monitoring of seawater intrusion; mountain front recharge (and flow across fault zones); managed aquifer recharge; and leakage through aquitards.

A total of 142 new piezometers have been installed at the site. This includes: 31 piezometers to monitor interaction between intermittent creeks and the groundwater system; 14 piezometers to monitor seawater intrusion; 12 piezometers installed across the fault zone between the hills and the plains to monitor mountain front recharge; 18 piezometers to monitor movement of artificially injected recharge; and 37 piezometers to monitor head gradients between the different aquifer layers, and the potential for inter-aquifer leakage. Most of these have been equipped with pressure transducers and data loggers to record water level fluctuations at fine temporal resolution.

A number of electrical conductivity sensors have also been installed. We have also installed six gauging stations on the Pedler Creek system to monitor river flow events, and four weather stations. A total of 49 soil moisture sensors have been installed beneath the creek system or in association with the weather stations. Studies of the water resources within the Willunga Basin involve strong collaboration with the NRM Board and the State Government. Infrastructure installed within the basin so far is being used by NCGRT PhD students Rachel Blakers (ANU), Michelle Irvine (FUSA) and Post-Doctoral Fellows Dr Sondoss El Sawah (ANU), Dr Michael Mitchell (CSU), Dr Jordi Batlle-Aguilar (FUSA), Dr Maria Pool, Dr Margaret Shanafield and Eddie Banks (FUSA). Dr El Sawah, Dr Mitchell and Mr Guillaume are building a socio-economic model and decision support system on top of this hydrological model, which will assist decision makers in the region. Dr Batlle-Aguilar is studying infiltration from intermittent streams into the groundwater system, and Dr Banks and Ms Irvine are working with CSIRO to develop tracer methods for measuring leakage through aquitards.

These projects are also being supported by international visitors to NCGRT, Dr Randal Hunt (United States Geological Survey), who is providing advice on development of the groundwater model, and Dr Suzanne Pearce (University of Texas), who is assisting the socio-economic study. However the infrastructure is also being used by researchers not directly affiliated with the NCGRT, and by the broader water industry. Data from stream gauging stations installed through the NCRIS project is currently publically available on the Adelaide and Mount Lofty Ranges NRM Board web site, and City of Onkaparinga Council have used streamflow data obtained from these stream gauges for flood mapping in the town of McLaren Vale. Rebecca Lester (Deakin University) is collaborating with researchers at ANU and CSU to modelling ecological response to groundwater extraction within the basin.