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

17 December 2021

THE BIG PICTURE
The 12-month forecast through August 2022 indicates widespread water surpluses in eastern Australia from southern Queensland through New South Wales into Victoria. Surpluses will be moderate to extreme south of Rockhampton, Queensland, moderate to severe between the Macintyre and Macquarie Rivers in New South Wales, and moderate from Canberra into Victoria. Moderate surpluses will also follow the Darling and Barwon River.

Moderate deficits are expected from Melbourne reaching west along the coast, becoming exceptional across the border into South Australia and extreme on Kangaroo Island and the southern tip of the Yorke Peninsula. Likewise, intense deficits are forecast in western Tasmania.

In Western Australia, extreme to exceptional water surpluses are forecast in the Swan-Avon catchment leading south. Moderate deficits are forecast along the coast in the nation’s southwestern tip, but deficits will reach exceptional intensity farther north in a pocket near Geraldton. Pockets of surplus will form a broken path from the Great Victoria Desert’s western edge nearly to the coast, and small pockets are expected in the Hamersley Range and Eighty Mile Beach in the state’s northwest. Small pockets of surplus are also forecast across the north in Northern Territory and coastal Cape York, but a pocket of intense deficit is expected south of Cairn on Queensland’s northern coast.

Normal water conditions are expected overall in New Zealand with surpluses north of Auckland and in East Cape, North Island. Transitional conditions (pink/purple) and surpluses are forecast in New Caledonia.

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

The forecast through February 2022 indicates that surpluses will increase in eastern Australia, becoming widespread from Rockhampton, Queensland through the eastern Murray-Darling Basin. Anomalies will be extreme to exceptional south of Rockhampton and in Murweh Shire, South West Queensland; moderate to extreme between the Macintyre and Macquarie Rivers in New South Wales; and moderate to severe from Canberra into Victoria. Moderate surpluses will follow the Murray, Darling, Barwon, and Lachlan Rivers, becoming more intense in the Lower Murray region of South Australia. Deficits will linger west of Melbourne and anomalies in Tasmania will shrink considerably. In Western Australia, intense surpluses will persist from the Swan-Avon River catchment east of Perth to the Upper Blackwood River catchment though deficits will persist in the nation’s southwestern tip along the coast. Pockets of surplus will form a broken path from the Great Victoria Desert’s western edge leading south, and moderate deficits are forecast in the state’s Mid West region. In Top End, Northern Territory, moderate surpluses are forecast in a pocket east of the Victoria River.

Surpluses will linger in East Cape, New Zealand, and scattered deficits elsewhere along the east coast. Mild to moderate surpluses are forecast in New Caledonia.

From March through May 2022, surpluses in eastern Australia will shrink and downgrade, persisting primarily from Rockhampton to Dubbo. In the west, however, surpluses will remain intense from the Swan-Avon catchment to the Upper Blackwood while deficits in the southwestern tip shrink. Scattered pockets of moderate surplus are forecast across northern Australia. Primarily mild surpluses are forecast in New Caledonia. Surpluses will increase in northeastern New Zealand; deficits will nearly disappear.

The forecast for the final months – June through August 2022 – indicates lingering pockets of surplus in eastern Australia and in the Swan-Avon catchment in the west. Exceptional deficits will emerge in Tasmania around Lakes Pedder and Gordon.

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

IMPACTS
This past month was the wettest November Australia has ever recorded with much of that excess precipitation falling in the nation’s east where many regions of Queensland and New South Wales experienced flooding.

At least two deaths have been reported, including one near Brisbane as floodwaters swallowed a car leaving a fast food drive-through. Flooding inundated Goondiwindi QLD, forcing nursing homes and hospitals to evacuate. Farmers in New South Wales had been projecting bumper crops before the deluge destroyed much of their harvest and reduced what remained of the wheat crop to animal fodder, commanding a lower price. Some residents of New South Wales were left stranded on islands in the floodplains.

Scientists in New South Wales warn that the flooding will result in an increase of invasive species in the state’s waterways, predicting an explosion of the European carp population in the Murray-Darling Basin.

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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