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Site Description

The Gnangara flux station is located in coastal heath Banksia woodland on the Swan Coastal Plain 70km north of Perth, Western Australia: (GPS coordinates: -31.3764, 115.7139; elevation: 51m), and 2km south of the University of Western Australia International Gravity Wave Observatory .

Climate summary taken from SILO DataDrill .

The site is a natural woodland of high species diversity. The overstorey is dominated by Banksia spp. mainly B. menziesii, B. attenuata, and B. grandis with a height of around 7m and leaf area index of about 0.8.

There are occasional stands of eucalypts and acacia that reach to 10m and have a denser foliage cover.

There are many former wetlands dotted around the woodland, most of which were inundated all winter and some had permanent water 30 years ago. The watertable has now fallen below the base of these systems and they are disconnected and are no longer permanently wet. The fine sediments, sometimes diatomaceous, hold water and they have perched watertables each winter.  There is a natural progression of species accompanying this process as they gradually become more dominated by more xeric species.

The soils are mainly Podosol sands, with low moisture holding capacity. Field capacity typically about 8 to 10%, and in summer these generally hold less than 2% moisture.

The watertable is at about 8.5 m below the surface, and a WA Dept of water long-term monitoring piezometer is near the base of the tower.

The instrument mast is 14m tall, with the eddy covariance instruments mounted at 14.8m.

Fluxes of carbon dioxide, water vapour and heat are quantified with open-path eddy covariance instrumentation. 

Ancillary measurements include temperature, air humidity, wind speed and direction, precipitation, incoming and outgoing shortwave radiation, incoming and outgoing long wave radiation, incoming total and diffuse PAR and reflected PAR. 

Soil water content and temperature are measured at six soil depths.  Surface soil heat fluxes are also measured.

A COSMOS Cosmic ray soil moisture instrument is installed, along with a logged piezometer, and nested piezometers installed with short screens for groundwater profile sampling.

To monitor the watertable gradient, piezometers will be installed 500 m esat and west of the tower.