La Niña and monsoonal winds flood northern Australia

Wendy Zukerman in New Scientist: Blame the strong La Niña and a monsoonal low-pressure zone for the devastating floods in the Australian state of Queensland that have left towns and cities stranded this week. In some parts of the state flood waters are now slowly receding, while other areas continue to wait for river levels to crest. The region's Fairbairn Dam remains over capacity, spewing 99,705 megalitres of water over its spillway daily.

At its peak, early on 31 December, the dam was at 176 per cent capacity, with water overflowing at a rate of 373,016 megalitres a day. Pradeep Singh of Australia's Bureau of Meteorology says heavy rains early last month saturated central Queensland and raised stream levels above average. But the final trigger was a deluge on 26 and 27 December, which broke river banks and flooded half of Queensland's 1.1 million square kilometres. Flooding now affects an area larger than Texas, or the size of France and Germany combined.

Jonathan Nott, a geoscientist specialising in extreme natural events at James Cook University in Cairns, Queensland, says pockets of heavy rain are common in the state. But this time the rain was unseasonably widespread and fell over the entire catchment area. "All of the tributaries that flow into the trunk stream, Fitzroy river, have been completely soaked," he says….

A deserted farmhouse on the outskirts of Maitland, N.S.W., when the town was ravaged by a flood, 1955, shot by Ern McQuillan