Australia & New Zealand: Water surpluses persist in E Australia

21 February 2022

THE BIG PICTURE
The 12-month forecast through October indicates widespread water surpluses in Australia’s east. Anomalies reaching extreme intensity are expected south of Rockhampton, Queensland, and a pocket in Paroo Shire in South West Queensland. Widespread moderate to severe surpluses are forecast in New South Wales and Victoria with surpluses expected from the eastern Murray-Darling Basin to the coast. Surpluses are also forecast along the paths of the Middle Darling and Lower Murray.

On Queensland’s northern coast a pocket of intense deficit is expected between Cairns and Townsville. Intense deficits are also expected in South Australia along the coast from Adelaide to the Victoria border and on Kangaroo Island. Extreme to exceptional deficits will dominate western Tasmania, the Derwent Estuary, and Hobart.

In Western Australia, extreme to exceptional water surpluses are forecast in the Avon River catchment leading south. A pocket of deficit is expected on the west coast between Geraldton and Perth, and also near Busselton. In the northwest, surpluses are forecast stretching from Eighty Mile Beach. In the nation’s vast Outback, pockets of surplus are forecast in the Gibson, Great Victoria, and Simpson Deserts.

In New Zealand, moderate to extreme deficits are predicted for South Island, particularly on the west coast. In North Island, moderate deficits are expected in the Waikato River catchment, and surpluses in East Cape. Mixed conditions are forecast in New Caledonia.

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

The forecast through April indicates that, while downgrading overall surpluses will remain widespread in eastern Australia from Rockhampton through the Murray-Darling Basin. Anomalies will be intense south of Rockhampton. Surpluses on the path of the Darling River will retreat. Surpluses will persist in the Grampians of western Victoria. Moderate deficits are forecast on the coast from Melbourne into South Australia. In Tasmania, moderate deficits will persist in the state’s western half and intense deficits from the Derwent Estuary to Hobart. Western Australia (WA) will continue to see intense surpluses in the Avon River catchment. Deficits will persist along the coast around Busselton and south of the Blackwood River, but deficits elsewhere in the west will nearly disappear. A wide path of surplus will emerge on WA’s northwestern coast stretching from Eighty Mile Beach.

In New Zealand, deficits in South Island will downgrade but remain widespread. Moderate deficits will increase in North Island from the Waikato River through Taranaki region in the west. In New Caledonia, deficits will nearly disappear in the north and surpluses will emerge in the south.

From May through July, surpluses in eastern Australia will shrink considerably, lingering south of Rockhampton, in pockets of the eastern Murray-Darling Basin, and in the Lower Murray region. Some pockets of intense deficit will linger in western Tasmania, including around Lakes Pedder and Gordon. In WA, deficits will retreat from the southwestern tip, surpluses in the Avon River catchment will shrink, and surpluses spanning Eighty Mile Beach will moderate overall. Deficits will shrink considerably in South Island, New Zealand, persisting on the south coast and nearby Stewart Island (Rakiura). In North Island, however, deficits in the west will intensify and surpluses will increase in East Cape.

The forecast for the final months – August through October – indicates that surpluses will increase in the eastern Murray-Darling Basin, becoming widespread. Exceptional deficits will emerge in Arnhem Land, Northern Territory.

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

IMPACTS
The Australian air force came to the rescue after late January flooding left the Outback community of Coober Pedy, 850 kilometers north of Adelaide in South Australia, cut off from critical supplies. With portions of a major highway and railway under water, tons of food and water were delivered by air. With few expedient alternate routes, the damages also disrupted grocery supplies to the states of Northern Territory and Western Australia. It took two weeks before Stuart Highway was reopened to traffic after more than a meter (3.28 feet) of water covering the roadway receded.

January rainfall across the state of New South Wales was 41 percent above the 1961-1990 average. Dams in the Greater Sydney area were at 96.4 percent capacity at the end of the month.

Widespread flooding struck the Kimberley region of Western Australia where the coastal city of Broome received more rainfall in 48 hours - 564 millimeters (22 inches) - than in all of 2021. Just north of Broome, 652 millimeters (25.7 inches) fell during a 24-hour period.

Severely drier than normal conditions have prompted Hamilton city officials in New Zealand’s Waikato River region of the north to declare a water alert level three, banning sprinkler use. The Matamata-Piako District is also at level three.

The tiny nearby nation of Tonga is suffering a drinking water shortage after an underwater volcano eruption on 15 January deposited a layer of ash that contaminated local supplies.

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.

Subscribe to our monthly Water Watch List

Search blog categories

Search blog tags