Australia & New Zealand: Water surplus will increase in NSW

23 September 2022

THE BIG PICTURE
The 12-month forecast through May 2023 indicates moderate to severe water surpluses in eastern New South Wales, Australia, from the Central West region surrounding Dubbo to the coast including Sydney.

In Queensland, moderate surpluses are forecast in a few pockets west of Brisbane, west of Dalrymple Lake in North Queensland, and north of the Holroyd River in the Cape York Peninsula.

Elsewhere in Australia, surpluses are forecast in the Tiwi Islands near Darwin in Northern Territory and in the Upper Avon River catchment of Western Australia.

Deficits will be widespread and exceptional in western and southern Tasmania, and pockets of deficit are forecast in the coastal mainland in Cape Otway, Victoria, and from the Eyre Peninsula in South Australia through Kangaroo Island and the Limestone Coast. In Western Australia, severe deficits are expected in Perth, becoming more intense as they reach south along the coast to Albany.

In New Zealand, pockets of primarily moderate surplus are forecast near Christchurch and in the northern half of South Island, and on North Island near Wellington, around the Bay of Plenty, and north of Auckland. Deficits are expected in South Island’s Fiordland. Near-normal conditions are expected in New Caledonia along with some surpluses.

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

The forecast through November indicates that surpluses in eastern Australia will increase. Surpluses are forecast from Wide Bay-Burnett in Queensland (QLD) through eastern New South Wales (NSW) to Canberra. Anomalies will be especially widespread in NSW, moderate to severe overall but extreme in a pocket north of Dubbo, and will reach inland to the confluence of the Macquarie and Barwon Rivers. Moderate surpluses are forecast on the Darling River and a few pockets in Gippsland, Victoria. In northern QLD, surpluses are forecast in Cairns and the Atherton Tableland nearby, and in the Cape York Peninsula near Princess Charlotte Bay. A few pockets of deficit are forecast in Top End, Northern Territory (NT) and deficits will linger along the coast in Western Australia’s (WA) southwestern tip. Nearby, surpluses are expected to persist in the Avon River region. Along Victoria’s coast, intense deficits will persist in Cape Otway. Widespread deficits will persist in Tasmania and islands in the Bass Strait. Anomalies will be intense from the city of Devonport in the north through the middle of the Tasmania to Hobart.

In New Zealand, surpluses will linger in near Christchurch and northern areas of South Island, and near Wellington and north of Auckland in North Island. New Caledonia will transition from deficit to surplus.

From December 2022 through February 2023, widespread surpluses will persist in eastern Australia, increasing past Canberra through Gippsland, Victoria, and moderate surpluses will emerge on the Lachlan and Murray Rivers from their confluence. Anomalies will be severe near Dubbo and Canberra. Moderate surpluses will increase in the Cape York Peninsula (QLD), and emerge in Top End and the Tiwi Island, transitioning from deficit in some areas. Surpluses will continue in WA’s Avon River Catchment and moderate deficits will linger along the coast in the state’s southwestern tip. Deficits will nearly disappear from coastal Victoria and Tasmania. Near-normal conditions are forecast in New Zealand. Moderate surpluses are forecast in southern New Caledonia.

The forecast for the final months – March through May 2023 – indicates lingering moderate surpluses in the Central West region of NSW and intense surpluses in the Avon River region in WA. Deficits will linger in Cape Otway, Victoria. Moderate surpluses will persist in southern New Caledonia.

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

IMPACTS
As noted in the Australian Bureau of Meteorology’s drought summary issued 5 September, since December of last year western Tasmania has experienced precipitation shortfalls in the lowest 10 percent of historical records.

In early August, Hydro Tasmania, a renewable energy provider, acknowledged that Tasmania’s energy storage had dropped to 32.7 percent, a figure below what the company calls “Prudent Storage Level.” Adjustment plans include importing more energy, exporting less, and the possibility of bringing a shuttered combined cycle gas turbine online.

In New South Wales, Australia, flood warnings were issued throughout the northeast in late September after 150 millimeters (~6 inches) of rain fell in just a few hours in the Northern Rivers region. Over a dozen flood rescue operations were conducted, nearly 200 emergency calls came in, and one car was swept into a creek on the Coffs Coast.

Flooding on the Namoi River left the town of Wee Waa in the state’s New England region stranded when the Kamilaroi Highway became submerged. Helicopters were deployed to deliver supplies. Cropland in the region has flooded multiple times in the last 12 months, with farmers predicting declines in wheat output. Fallowed fields allotted for sorghum and cotton are under water.

Estimates for insurance claims from flooding in February and March in Queensland and New South Wales now total AU $5.28 billion (US $3.45 billion).

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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