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

25 May 2022

THE BIG PICTURE
The 12-month forecast through January 2023 indicates widespread water surpluses in eastern Australia from Rockhampton, Queensland through eastern Victoria. Anomalies will be widespread in New South Wales reaching extreme to exceptional intensity in the North Coast region and around Sydney, and will be extreme in East Gippsland, Victoria. Surpluses will extend inland to the Macquarie and Lachlan Rivers, and moderate surpluses will trace the path of the Darling River. Surpluses are also expected in Far North Queensland north of the Holroyd River in Cape York Peninsula.

Deficits are expected across northern Australia from the Kimberley in Western Australia where anomalies will be moderate through the southern coast of the Gulf of Carpentaria where deficits will be more intense. Moderate to severe deficits are also forecast in the Victoria River catchment in Northern Territory.

In the nation’s southwest corner, moderate to exceptional surpluses are forecast in the Avon River catchment, with transitional conditions to the south leading to moderate deficits in Albany and along the coast to Busselton.

Severe to exceptional deficits will dominate western Tasmania, the Derwent Estuary, and Hobart.

In New Zealand, deficits of varying intensity are predicted for South Island’s southern half. Anomalies will be exceptional in parts of Southland. Moderate surpluses are expected in Hawke’s Bay Region on North Island, becoming intense in East Cape. Moderate surpluses are also forecast in Northland, New Zealand and in southern New Caledonia.

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

FORECAST BREAKDOWN
The forecast through July indicates that while downgrading, surpluses will remain widespread in eastern Australia from just south of Rockhampton, Queensland (QLD), through Brisbane and the Murray-Darling Basin into East Gippsland, Victoria. Anomalies will be moderate to severe overall but are expected to be extreme in a pocket north of Dubbo, New South Wales. Moderate surpluses will trace the Darling and Lachlan Rivers, but more intense surpluses are forecast in the lower Murray region. Surpluses will emerge in Far North QLD north of the Holroyd River in Cape York Peninsula and will intensify in a small pocket west of Cairns. Exceptional deficits will emerge in Northern Territory (NT) in the Victoria River region, around the town of Katherine, and near the southern coast of the Gulf of Carpentaria. In Western Australia (WA), surpluses will shrink in the greater Avon River region and pockets of moderate surplus will re-emerge in the Great Victorian Desert and western Nullarbor Plain. In Tasmania, intense deficits are expected in the west, Derwent Estuary, and Hobart.

Anomalies in New Zealand will shrink but intense deficits are forecast in South Island’s southern half, and surpluses will persist in Northland and Gisborne Region in North Island. Moderate surpluses are expected in southern New Caledonia.

From August through October, widespread surpluses will persist in eastern Australia, emerging in the Mackenzie River catchment west of Rockhampton and becoming severe on the Darling River. Extreme surpluses will emerge west of Brisbane and increase north of Dubbo. Surpluses will persist in the northern area of the York Peninsula and a pocket west of Cairns. Intense deficits in northern Australia will shrink considerably, lingering on the Gulf Coast. Near-normal water conditions are forecast for WA. Deficits will remain intense in Tasmania but will shrink somewhat. Anomalies in New Zealand will shrink considerably, leaving small pockets, and surpluses in New Caledonia will become merely mild.

The forecast for the final months – November through January – indicates that widespread surpluses will increase in eastern Australia and the Cape York Peninsula, and surpluses will emerge in Top End, NT and the Ord River region in WA.

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

IMPACTS
February through March flooding in Australia’s New South Wales and Queensland was the most costly in the nation’s history reports the Insurance Council of Australia. By early May, 197,000 claims were filed for flood damages with an estimated AU $3.35 billion (US $2.36 billion) in insured losses.

Damage estimates from February flooding in Brisbane alone total $660 million (US $467 million). Destroyed infrastructure includes 300 playgrounds, 863 parks, 106 sports fields, 285km (177 miles) of roads, over 4000 streetlights, and 198 community clubs.

Intense rainfall in mid-May claimed one life in Mount Ossa in Queensland’s coastal north. Rainfall totals reached 170 mm (6.7 inches) in 24 hours in some areas of the state. By 13 May, over 700 Queensland roadways were inundated. With reservoir levels high, authorities released water from several dams including the Wivenhoe Dam west of Brisbane.

Official drought designation in New Zealand’s Waikato and South Auckland regions has triggered a package of support for farmers including tax flexibility and feed coordination.

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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