Australian Natural Resources Atlas

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Water resources - Overview - Queensland

Location map of Winton / Mackunda Formations

Groundwater Management Unit: Winton / Mackunda Formations

Introduction

The Winton and Mackunda Formations are located in one of Australia's most extensive sedimentary basins, the Eromanga Basin. The formations are geological units within the Rolling Downs Group of the Eromanga Basin Sequence. The Winton/Mackunda Groundwater Management Unit (GMU) covers an area of approximately 271180 sq km across South Western Queensland. The GMU boundary is defined by a combination of the extent of the geological outcropping of the Winton and Mackunda Formations, the Queensland State boundary and Shire boundaries. The towns of Barcaldine, Blackall, Longreach, Winton and Birdsville fall within this boundary. The GMU is drained in a south-westerly direction by the Diamantina, Thomson and Barcoo Rivers.

The Winton and Mackunda Formations overly the Great Artesian Basin (GAB). The GAB is very deep across most of the GMU and drilling into this groundwater resource is expensive. This means that for a great extent of the GMU, groundwater from the Winton and Mackunda aquifer systems is the only available water supply. Consequently, the sub-artesian groundwater resources in the Winton/Mackunda GMU are in high demand.

Groundwater in the Winton/Mackunda GMU is used for stock and domestic purposes with bore yields of less than 2.5 l/s. There is increasing concern over large geographical areas within the GMU about the suitability of the resource for such purposes with degrading water quality and reduced bore yields. The seriousness of the situation is depicted in the 41 % abandonment rate of bores.

The Winton/Mackunda GMU experiences a semi-arid to arid climate with unreliable rainfall and is prone to drought conditions. The annual average rainfall for the GMU is 410 mm with approximately 60 % occurring between the months of December and March, inclusive. There is a continual decrease in mean annual rainfall from the north-east, which receives 445 mm/yr, to the south-west of the GMU, 166 mm/y. The distribution and variability of rainfall promotes the perception that the groundwater resources are more reliable than the surface water resources.

Vital Statistics:

Area: 271,180 Km2
Total water allocated: no data
Total water consumed: 136,320 ML/yr
Average salinity: 3,041 mg/l
Sustainable yield: 24,000 ML/yr
Depth to top of aquifier: 79 m

Further Information

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