Australia & New Zealand: Water surplus in E Australia will persist

17 March 2022

THE BIG PICTURE
The 12-month forecast through November indicates widespread water surpluses in eastern Australia from Rockhampton, Queensland through eastern Victoria.

Anomalies will be widespread in New South Wales reaching exceptional intensity in the North Coast region and severe to extreme intensity in Sydney. Surpluses are also forecast along the Lachlan and Murray Rivers.

Some areas of intense deficit are expected across northern Australia. Deficits will be severe to exceptional in the Victoria River catchment of Northern Territory, along the western corner of the Gulf of Carpentaria, and from the Gregory Range in northern Queensland to the coast near Townsville. Deficits of generally lesser intensity are forecast east of Darwin in coastal Top End, Northern Territory, and pockets in the Kimberley in Western Australia. In the nation’s southwest corner, severe to exceptional water surpluses are forecast in the Avon River catchment leading south, and deficits will skirt the coast near Busselton.

Severe to exceptional deficits will dominate western Tasmania, the Derwent Estuary, and Hobart. Deficits are also expected on Kangaroo Island off mainland Australia near Adelaide and in the Limestone Coast region to the east.

In New Zealand, moderate to extreme deficits are predicted for South Island’s southern half, and surpluses in coastal areas of the north. Surpluses are also expected in North Island from Wellington to East Cape. In New Caledonia, moderate surpluses are forecast in the south.

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

The forecast through May indicates that while downgrading, surpluses will remain widespread in eastern Australia from Bundaberg on Queensland’s coast through the Murray-Darling Basin and coastal regions into Victoria. Anomalies will be moderate to severe. Surpluses will shrink in the Shire of Paroo in South West Queensland, but persist in the Grampians of western Victoria, and intense surpluses will re-emerge in the Lower Murray region. Deficits will linger on the coast west of Melbourne and are also forecast on northern Queensland’s coast between Cairns and Townsville and near Rockhampton. Western Australia will continue to see intense surpluses in the Avon River catchment and deficits will persist in Busselton. In Tasmania, moderate deficits are forecast in the south and moderate surpluses will emerge in the northeast corner. In New Zealand, deficits are forecast in South Island’s southern tip and nearby Stewart Island, and surpluses are forecast in the island’s northern half and across Cook Strait into North Island from Wellington through East Cape. Surpluses are also forecast in the southern half of New Caledonia.

From June through August, surpluses in eastern Australia will continue to shrink and downgrade but will remain widespread in eastern New South Wales. Anomalies will be mild to severe. In Top End, Northern Territory, small pockets of exceptional deficit will emerge in coastal Arnhem Land, in the Victoria River catchment, and also in the northern Kimberley region of Western Australia. In Tasmania, moderate deficits are expected in Hobart and the Derwent Estuary and exceptional deficits near Lakes Gordon and Pedder. Deficits will linger in South Island’s southern tip, and surpluses are expected in Christchurch and coastal extremes in North Island. Moderate surpluses will persist in southern New Caledonia.

The forecast for the final months – September through November – indicates that surpluses will increase in southeastern Australia, moderate overall but severe to extreme from Dubbo to Armidale in New South Wales. Deficits will retreat. Surpluses will increase in North Island and New Caledonia.

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

IMPACTS
After weeks of widespread flooding in the nation’s east, the Australian government declared a national emergency earmarking millions of dollars in flood aid including AU 2,000 (USD $1,460) per person. Flooding has claimed 22 lives so far in the affected areas of southeastern Queensland, northern New South Wales, and the metropolis of Sydney. Around 7,000 defense personnel have been deployed to help with flood recovery. Nearly a year’s worth of rainfall inundated the flood regions in just a week, with more in the forecast. Evacuation orders were issued for 60,000 people in Sydney alone with the possibility of up to 500,000 being warned throughout New South Wales and Queensland. Current estimates of flood costs have risen to AU $1.62 billion (US $1.19 billion.)

An outbreak of Japanese encephalitis in Australia has prompted the government to allocate AU $69 million to combat the mosquito-borne illness, including AU $28 million for additional vaccines. Climatic conditions favoring wetter weather provide breeding grounds for water birds who transfer the virus to mosquitoes, leading to human infections.

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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