Australia & New Zealand: Water deficits in New Zealand will shrink

20 August 2021

THE BIG PICTURE
The 12-month forecast through April 2022 indicates extreme to exceptional water surpluses in Western Australia in the Avon River catchment, while in the state’s southern tip deficits are expected in Busselton and the lower Blackwood River region. In eastern Australia, moderate to severe surpluses are forecast for the Macintyre River region of northeastern New South Wales.

Surpluses, generally moderate, are forecast for some pockets in Victoria, South Australia, and scattered across Australia’s northern regions. Near the Lower Murray River, intense surpluses and transitional conditions are expected.

ISciences_Australia_New_Zealand_Composite_Adjusted_202105-202204_12mo_twitter.png

Deficits are expected in a few pockets along the southern coast including the west coast of the Eyre Peninsula and Kangaroo Island. Deficits will be more intense in Tasmania, extreme near Hobart and around Lakes Gordon and Pedder and severe throughout much of western Tasmania.

In New Zealand, moderate deficits are expected around Hawke’s Bay in the north and moderate surpluses in the Fiordland region of South Island. New Caledonia’s northern half will experience severe deficits.

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

The forecast through October indicates that surpluses in southeastern Australia will shrink, persisting in the Macintyre River region in northeastern New South Wales and north of Grampians National Park in Victoria. Intense surpluses will persist in Western Australia in the Avon River catchment east of Perth and extending to the southern coast. Surpluses are expected to re-emerge in Western Australia from the Gibson Desert leading south, and around Katherine in Northern Territory. Also in the north, exceptional deficits will emerge in eastern Arnhem Land in Top End, Northern Territory, and in Queensland at the base of the Gulf of Carpentaria and tip of the Cape York Peninsula. Surpluses in the Peninsula will recede. In Tasmania, deficits will retreat from the Derwent Estuary but will intensify in the west, becoming exceptional. While shrinking overall in New Zealand, deficits are forecast around Hawke’s Bay in the north and a few pockets in the south. Surpluses in Fiordland will moderate. In New Caledonia, deficits will increase but downgrade from exceptional to moderate or severe.

ISciences_Australia_New_Zealand_Composite_Adjusted_202105-202204_3mo_twitter.png

From November 2021 through January 2022, moderate surpluses will increase between the Macintyre and Macquarie Rivers in New South Wales and will emerge from Canberra to the coast. Intense surpluses are forecast in the Lower Murray River. In the west, surpluses will remain intense in the Avon River Watershed and southwest of the Gibson Desert. Across Australia’s northern reaches, deficits will disappear and moderate surpluses will increase in Top End. Surpluses will emerge in a small pocket on the east coast north of Rockhampton and mild surpluses are expected in the Cape York Peninsula. Near-normal water conditions are forecast for Tasmania, New Zealand, and New Caledonia.

The forecast for the final months – February through April 2022 – indicates that surpluses will nearly disappear in the nation’s southeast, remain intense in Western Australia’s Avon River Watershed, shrink in Top End, and emerge in the Ord River region of Western Australia and Northern Territory. Some pockets of moderate surplus will emerge in northern Queensland and moderate surpluses are expected in New Caledonia.

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

IMPACTS
Perth, Australia experienced its wettest July in 60 years, including heavy rainfall at the end of the month that brought flash flooding to the region and windspeeds up to 135 kilometers per hour (84 miles per hour), ripping trees from the ground and rooves from houses. Over 20,000 homes and businesses lost power, train travel was disrupted, and one local park turned into a lake. Flooding earlier in the month turned streets into rivers, trapping some drivers in their cars.

Heavy rain fell on already saturated ground in Armidale, New South Wales in early August, flooding many city streets. The state’s dams were at 97 percent capacity at the end of July, prompting water authorities to order controlled releases in anticipation of continued precipitation.

A recent report by Australia’s federal agricultural research agency indicates that climate change has reduced farm profits in the nation by 23 percent over the last 20 years, about $29,000 per farm, compared to the period between 1950 and 2000. Since 2000, Australia has become warmer overall and drier in the southwest and southeast.

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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