Australia & New Zealand: Intense water deficits will persist in Tasmania

18 February 2019

THE BIG PICTURE
The 12-month forecast through October 2019 shows widespread, exceptional water deficits in Australia’s Outback and South Australia, as well pockets in the north, Queensland, along Victoria’s shore, and western Tasmania.

Intense deficits are forecast south of Rockhampton in eastern Queensland and around Brisbane; around Darwin in Top End, Northern Territory and along the southern shore of the Gulf of Carpentaria; in the northern Kimberley region of Western Australia; and in the Blackwood River region near Busselton in the tip of Western Australia.

In the Murray-Darling Basin in the southeastern quadrant of Australia, deficits are expected to be moderate on the Lachlan River, primarily severe on the Murray, and severe to extreme on the Darling.

Some pockets of moderate to exceptional deficit are forecast in New Zealand, and extreme deficits in New Caledonia.

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

The forecast through April indicates that the intense deficits that have dominated many parts of Australia in prior months will nearly disappear. However, severe to exceptional deficits will persist in Tasmania; along Victoria’s coast, particularly around Melbourne; in the Strzelecki Desert in northwestern New South Wales (NSW) and the eastern portion of the Lake Eyre drainage basin; and in the Blackwood River region in the tip of Western Australia (WA). Primarily moderate deficits are forecast for southern South Australia and much of Victoria, but deficits are expected to be severe along the Murray River. Moderate deficits are also forecast for eastern Queensland (QLD) but severe to extreme pockets are expected in a path following the coast from Rockhampton through Brisbane and into NSW. Surpluses in pockets of northeastern QLD will moderate.

Moderate deficits will cover most of Australia’s northwestern quadrant, but deficits will be severe to extreme in some pockets including northern Kimberley in Western Australia (WA) and western Top End in Northern Territory (NT).

Deficits in New Caledonia will downgrade, becoming moderate to extreme. Primarily moderate deficits are forecast in pockets of New Zealand, but conditions may be more intense in the Tasman District of northern South Island and across Cook Strait in the Taranaki region of North Island.

From May through July, intense deficits will nearly disappear in the region leaving merely mild deficits in much of Australia though conditions will be more intense across the north. Moderate deficits with severe to exceptional pockets are forecast in Kimberley, WA; Top End, NT; and Cape York. Deficits in the tip of WA will downgrade to severe but moderate deficits will emerge in regions just north, including Perth. Some moderate deficits will linger in southeastern Australia, but nearly normal conditions are forecast for the Murray-Darling Basin. Moderate to extreme deficits will persist in Tasmania and are expected to be most intense in the Derwent River Valley. In New Zealand, some moderate to extreme deficits are expected, particularly in the Taranaki region of Northern Island. Deficits in New Caledonia will moderate.

The forecast for the final months – August through October – indicates that deficits in northern Australia will intensify with exceptional anomalies in Top End, NT and pockets in Kimberley and Cape York. Near-normal conditions are expected in much of the rest of the country with some severe deficits in Tasmania and in the tip of WA. Deficits will shrink and downgrade in New Zealand; moderate to severe deficits are forecast in New Caledonia.

(It should be noted that forecast skill declines with longer lead times.)

IMPACTS
A month following intense bushfires in drought-ridden Queensland, the state was pelted by Cyclone Owen with up to 681mm (26.8 inches) of rain, prompting floodwater rescues and official warnings to beware crocodiles lurking in the floodwaters.

Storm systems linked to Owen extended southward, dumping up to five times the average December rain totals within a week in Australia’s southeastern state of Victoria. Despite flood damage to some crops and pastures, the intense rain was largely welcomed by farmers, whose year was set to be the driest on record prior to the storm.

Queensland was again pelted by heavy rain for weeks on end in late January and early February, killing hundreds of thousands of drought-weakened cattle amid exposure to flooding, with some areas reportedly receiving over a year’s worth of rain in a week.

Western-Australian grain normally exported abroad was instead imported last month to the country’s eastern states, where intense drought in the last twelve months has prevented regional supply from keeping up with demand. This was the first export diversion since the Millennium drought ten years ago.

Adding a painful estimate of one million dead fish, the second substantial fish kill within a month occurred in the Lower Darling River near the Menindee Lakes in New South Wales, worrying experts that entire populations of Murray cod and other native fishes have been wiped out. At the time of the recent fish kill the water level in the lakes was just 2.5 percent. The incident sparked outrage and blame-throwing onto state-owned WaterNSW, which manages the Murray-Darling River system, and the cotton industry, which has been accused of over-extracting water resources. In what it admitted to be a ”band-aid solution,” the state announced plans to use battery-powered aerators to pump oxygen into the water to prevent further deaths.

For the last 18 months, New South Wales has faced what the state’s water management claims to be unprecedented drought conditions, threatening total drying of the Burrendong Dam and Namoi River. Experts contend, however, that water extraction permits have been far too liberal, given the perennial warnings of the collapse of the Murray-Darling Basin since the 1990’s.

In the outback of Australia’s Northern Territory, roughly 90 wild horses were found lying in a dried riverbed last month, dying or having died from starvation and dehydration.

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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