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Unprecedented flooding hits Australia's Queensland

By: Dr. Jeff Masters, 10:57 PM GMT on December 29, 2010

Unprecedented flooding has hit the northeast Australian state of Queensland, thanks to a week and a half of torrential rains and the landfall of Tropical Cyclone Tasha on Christmas Day. Australian Prime Minister Julia Gillard stated yesterday, "Some communities are seeing flood waters higher than they've seen in decades, and for some communities flood waters have never reached these levels before [in] the time that we have been recording floods." The worst flooding occurred where Tropical Cyclone Tasha made landfall on Christmas Day. Though Tasha was a minimal tropical storm with 40 mph winds and lasted less than a day, the cyclone dumped very heavy rains of 8 - 16 inches (about 200 - 400 mm) on a region that was already waterlogged from months of heavy rains. According to the National Climatic Data Center, springtime in Australia (September - November) had precipitation 125% of normal--the wettest spring in the country since records began 111 years ago. Some sections of coastal Queensland received over 4 feet (1200 mm) of rain from September through November. Rainfall in Australia in December may also set a record for rainiest December. The heavy rains are due, in part, to the moderate to strong La Niña event that has been in place since July. While the rains have eased over Queensland over the past few days, some rivers will not reach peak flood stage until Friday. Approximately 1000 people have been evacuated from the affected area so far.

Figure 1. Rainfall in Queensland, Australia for the 7-day period ending December 29, 2010. Image credit: Australian Bureau of Meteorology.

Figure 2. Radar image of Tropical Cyclone Tasha as it moved inland over Queensland, Australia on Christmas Day (local time.) Image credit: Australian Bureau of Meteorology.

Figure 3. River conditions in Queensland as of 8:30am local time on December 30, 2010. Image credit: Australian Bureau of Meteorology.

Flood warnings are in effect for over twelve rivers, and the flooding has closed approximately 300 roads across Queensland, including two major highways into the capital of Brisbane. Evacuations are underway in Rockhampton, a city of 50,000 people on the coast. Damage to infrastructure in Australia has been estimated at over $1 billion by the government, and economists have estimated the Australian economy will suffer an additional $6 billion in damage over the coming months due to reduced exports, according to insurance company AIR Worldwide. Queensland is Australia's top coal-producing state, and coal mining and delivery operations are being severely hampered by the flooding. Damage to agriculture is curently estimated at $400 million, and is expected to rise.

Flooding woes hit New Zealand
Wild weather has also hit New Zealand this week. Golden Bay on the northern end of the South Island of New Zealand had its worst floods in 150 years this week, thanks to torrential rains that dropped up to 13.2 inches (337.5 mm) in just 24 hours on Monday at one mountain location.

Figure 4. Two webcam views of the Motueka River in New Zealand taken five hours apart on December 28, 2010, showing the dramatic rise in the river due to flooding rains. Image credit: Tasman District Council. Screen shots kindly sent to me by Matt Johnson.

Jeff Masters


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