Australia & New Zealand: Water surplus in Macintyre & Avon Basins

29 October 2021

THE BIG PICTURE
The 12-month forecast through June 2022 indicates extreme to exceptional water surpluses in Western Australia in the Avon River catchment. Deficits are forecast along the southwestern coast, severe near Geraldton and extreme to exceptional from Busselton around the nation’s southwestern tip.

Deficits are also expected in pockets of the coastal south on the Eyre Peninsula, Kangaroo Island, and nearby on the mainland to Melbourne, and will be intense in some areas. Intense deficits are forecast in western and southern Tasmania. In South Australia near the Lower Murray River, surpluses and transitional conditions are expected. Severe surpluses are expected in the Grampians region of western Victoria, and pockets of moderate surplus in the Australian Alps.

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In eastern Australia, moderate to severe surpluses are forecast for the Macintyre River region of northeastern New South Wales. In the nation’s north, surpluses are expected at the tip of the Cape York Peninsula in Far North Queensland and in the islands off Top End in Northern Territory.

Normal water conditions are expected overall in New Zealand with a small area of moderate deficit north of Dunedin and severe surpluses on the points framing the Bay of Plenty. Mixed conditions are forecast in New Caledonia.

FORECAST BREAKDOWN
The 3-month maps (below) show the evolving conditions in greater detail.

The forecast through December indicates normal water conditions in much of the region. Moderate to severe surpluses are forecast in the Macintyre River area in northeastern New South Wales, moderate surpluses north of Grampians National Park in Victoria, and milder surpluses near the Australian Alps. Deficits will shrink and downgrade around Dubbo in New South Wales, west of Melbourne, and in Tasmania, though anomalies near Hobart will be severe. In Western Australia, intense surpluses will persist in the Avon River catchment east of Perth and extending south, but deficits of varying intensity are forecast along the coast from Perth well past Busselton. Surpluses are expected to re-emerge in Western Australia in the Lake Carnegie region southwest of the Gibson Desert. Some generally mild surpluses are forecast in the nation’s far north.

ISciences_Australia_New_Zealand_Composite_Adjusted_202107-202206_3mo_twitter.png

A few pockets of moderate deficit will skirt New Zealand’s southeastern coast and surpluses are expected on the points framing the Bay of Plenty on North Island. Moderate deficits are forecast in New Caledonia.

From January through March 2022, deficits will nearly disappear, persisting primarily in Australia’s southwestern tip. Surpluses will persist in the Avon River catchment in the west but retreat from the Lake Carnegie region. Moderate surpluses will continue near the Grampians and in the Macintyre River region, and increase east of the Australia Alps and in the far north. Deficits will retreat from New Caledonia as mild surpluses emerge.

The forecast for the final months – April through June 2022 – indicates persistent, intense surpluses in the Avon River Watershed while coastal deficits nearby nearly disappear. Surpluses elsewhere in Australia will shrink, persisting primarily in the Macintyre River region. Moderate surpluses are forecast throughout New Caledonia.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
Torrential rain and a tornado struck the Australian city of Armidale, located in the tablelands region of New South Wales, in mid-October. Over, 5,000 people were evacuated during the potent mix of destructive weather that included flash flooding, hail, and dangerous winds. The storm knocked out power to half of the city’s residents, flipped cars, and stripped roofs from houses.

Though drought has retreated from nearly all of Australia, a few isolated areas remain barren with one cattle farmer in central Queensland’s Longreach Region describing his area as a “moonscape.” The loss of pasture has been devastating. Farther east, the North Burnett Region has received about half its normal rainfall this year through September, the lowest on record.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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