Natural Environment GN

Climate

The climate in the Goldfields-Nullarbor subregion is arid to semi-arid, with hot summers and mild winters. Summers in this subregion are extremely variable; daily temperatures exceeding 40°C can be followed by cloudy days with temperatures in the low 20’s. The mean average summer temperature ranges from 16°C to 34°C.The mean average winter temperature ranges from 4°C to 17°C.

Within the subregion there is a rainfall gradient; in the southwest area there is a winter rainfall regime of about 300 mm annual rainfall while in the northern Nullarbor area there is a non-seasonal regime of about 150 mm annual rainfall. Tropical cyclones influence the region in the form of rain-bearing depression and can often result in large rainfall events. The average yearly evaporation exceeds the average yearly rainfall and is about 2400 to 2800 mm.

Goldfields - Nullarbor Enviro Photo

View from Mt Jimbalana. Photo by Tiffany Bennett

Rivers

The Goldfields-Nullarbor subregion is almost completely devoid of major riverine landform features and there are no permanent watercourses. Most of the river systems within this subregion are short and all of them are ephemeral and infrequently, flowing briefly following large episodic rainfall events like tropical cyclones. Three ‘wild rivers’ have been identified within this region; these are Savory Creek, Herbert Wash and Ponton Creek.

Wetlands

The Goldfields-Nullarbor subregion has no permanent watercourses; however, there are numerous salt lakes of varying sizes throughout the area.

Coastline

The coastline and marine environment of the Goldfields-Nullarbor subregion is poorly researched. It is known that the subregion is an important habitat for marine mammals and that offshore areas feature algal beds and seagrass meadows.

The subregion hosts a number of species which are of commercial and/or recreational value, these species include Southern Rock Lobster (Jasus edwardsii), several abalone species, scallops, snapper, trevally, cod and leatherjackets.

Flora and Fauna

The Coolgardie IBRA subregion is especially important as a biogeographic interzone between the moist south-west and the arid interior of the state. This IBRA subregion contains floristic elements of both zones and as a result exhibits high levels of ecological community diversity as well as a high level of species diversity.

This subregion contains 30 spcies of Declared Rare Flora (DRF), 100 Priority One Flora, 57 Priority Two Flora, 112 Priority Three Flora and 36 Priority Four Flora and 63 threatened or priority animal species. No known threatened ecological communities occur within this subregion.

Vegetation

In the Goldfields-Nullabor subregion there are 5 broad types of vegetation community. The treeless Nullarbor Plain and its surroundings are dominated by low halophyte and saprophyte communities sometimes. The arid regions of the central north and north-east consist of areas of hummock grasslands with various tree and shrub associations as well as areas of low open mulga woodlands. The central west and north-west are predominantly mulga woodlands with smaller areas of shrubland and hummock grasslands. The south west part of the subregion has a complex mix of vegetation types, this includes tall woodlands as well as areas of shrub-heath and tall shrubland. These woodlands are globally unique and are the largest remaining area of intact mediterranean climate woodland on Earth. The coastline and eastern margins are colonised with a range of shrubland and low woodlands dominated by acacia and eucalyptus.

IBRA Subregions

The Goldfields-Nullarbor contains three IBRA sub-regions: Nullarbor, Hampton and Coolgardie. To read more about IBRA subregions, and to access the Australian Government's detailed descriptions of each, see the IBRA subregions page.