Australia & New Zealand: Water surplus in SE & far north Australia

21 November 2021

THE BIG PICTURE
The 12-month forecast through July 2022 indicates extreme to exceptional water surpluses in Western Australia in the Avon River catchment leading south. Deficits are forecast nearby along the southwestern coast, moderate near Geraldton but extreme to exceptional from Busselton around the nation’s southwestern tip.

Deficits are also expected in pockets of Australia’s coastal south on the Eyre Peninsula, Kangaroo Island, and nearby on the mainland to Melbourne, and will be intense in some areas. Intense deficits are forecast in western and southern Tasmania. In South Australia near the Lower Murray River, surpluses and transitional conditions are expected. Severe surpluses are expected in the Grampians region of western Victoria and pockets of moderate surplus in the Australian Alps.

In eastern Australia, moderate to severe surpluses are forecast for the Macintyre River region of northeastern New South Wales. In the nation’s north, surpluses are expected at the tip of the Cape York Peninsula in Far North Queensland and in Northern Territory’s Barkly Tableland, Arnhem Land, and the islands off Top End.

Normal water conditions are expected overall in New Zealand with surpluses north of Auckland and on the points framing the Bay of Plenty. Moderate deficits are forecast along the southeastern coast of South Island. Mixed conditions are forecast in New Caledonia.

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

The forecast through January 2022 indicates normal water conditions in much of the region. Deficits will retreat across Australia’s north, transitioning to moderate surplus in Far North Queensland, Top End Northern Territory, and the Kimberley region of Western Australia. In southeastern Australia, moderate surpluses are forecast in the Macintyre River area in New South Wales, from Canberra through the Australian Alps to the coast, and pockets in eastern Tasmania. Surpluses will reach severe intensity north of Grampians National Park in Victoria and will be exceptional in the Lower Murray River region of South Australia. In Western Australia, intense surpluses will persist in the Avon River catchment east of Perth and extending south into the Upper Blackwood River region, but deficits will persist in the nation’s southwestern tip along the coast from Busselton. Surpluses are expected to re-emerge in Western Australia in the Lake Carnegie region southwest of the Gibson Desert.

Deficits are forecast in southeastern New Zealand and surpluses north of Auckland and around the Bay of Plenty. Near-normal conditions are expected in New Caledonia.

From February through April 2022, intense surpluses will persist from the Avon to Blackwood River regions in Western Australia, but surpluses elsewhere will shrink. Exceptional deficits are forecast to emerge near Lake Eyre in South Australia. Anomalies in New Zealand will shrink, and mild surpluses will emerge in New Caledonia.

The forecast for the final months – May through July 2022 – indicates pockets of surplus in the Macintyre River region, the Avon River Watershed, and the Barkly Tableland. Exceptional deficits will emerge around Lakes Pedder and Gordon in Tasmania.

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

IMPACTS
Outback Queensland is celebrating increased rainfall this November, a welcome relief for the region’s livestock farmers. Bedourie in Channel Country received almost 100 millimeters (nearly 4 inches) over the course of 48 hours, and Birdsville near the Simpson Desert received 27 millimeters (1 inch), its highest November precipitation in over two decades.

The precipitation has not been welcome, however, in parts of New South Wales, Australia, where farmers are worried about losing crops and pastures to flooding. The water level has been rising on the Lachlan River through November, spreading quickly across its floodplain. Floodwaters have already inundated much of the land around the town of Forbes, where damage to agriculture and property is still being tallied. Cash crops were within just days of harvest and with grazing areas submerged, ranchers are facing high feed costs.

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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