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Australia is back in the midst of a big flood! Torrential rains hit the southeast coast of Australia, forcing thousands of people to flee their homes due to the risk of flooding and landslides in a region that has been hit by severe flooding four times in the past 18 months. Parts of New South Wales have seen months of rain in recent days, causing rivers to burst their banks and Sydney's main dam, Warragamba, to release water. The Insurance Council of Australia estimated that flooding in March and April in New South Wales and southeast Queensland resulted in A$4.8 billion (€3.1 billion) in insured damages. Australia has been hit by the Pacific La Niña weather event for two consecutive years, which typically brings above average rainfall on the east coast. According to the Bureau of Meteorology, the La Niña event ended in June, but there is a 50/50 chance it could happen again later this year. High ocean surface temperatures and another phenomenon, the Indian Ocean dipole, are bringing wetter than normal weather. In June, the Met Office reported that the Indian Ocean dipole index turned negative in May, raising the chance of above-average winter and spring precipitation across much of Australia. During a negative Indian Ocean dipole, the eastern Indian Ocean is warmer than normal and the western Indian Ocean, near Africa, is colder, resulting in more humid air flowing into Australia. Mortlock said it's difficult to link any single flood to climate change, as the increase in heavy rainfall is in line with what can be expected from climate change as warmer air holds more moisture in the atmosphere. “Most climate models suggest an increase in the frequency of rain in Australia,“ he said. According to the NSW Public Emergency Service, the Hawkesbury Nepean Valley in Western Sydney is a floodplain prone to dangerous flooding due to the “bathtub effect“. The valley is fed by five tributaries and has bottlenecks that restrict flow to the sea, so during heavy rains, water accumulates. Torrential rains caused by La Nina over the past two years have soaked the ground and filled in levees, setting the stage for flash floods. “In the watersheds on the east coast, there is little to no filtration capacity,” Mortlock said. Sydney's rapid population growth over the past few decades has pushed development into the floodplain. Prior to the recent floods, there had been no major flooding for about three decades, which meant that officials approving land development applications could assume there was little risk of flooding. “When you don’t have it for a long time, there’s a lot of complacency,” said Ian Wright, an environmental scientist at the University of Western Sydney. “Our bridges are not high enough,” he said. “Escape routes in case of flooding are few and inadequate.“ Residents and emergency workers are still recovering from the wildfires of 2019-2022 and the floods of last and this year amid the Covid-19 pandemic. Wright said the lack of building materials and labor means thousands of people are waiting for repairs after previous natural disasters. Adding to the vulnerability, many low-income residents of western Sydney cannot afford flood insurance. Emergency Situations Minister Murray Watt said the new Labor government wants to be more proactive in dealing with disaster risk. “Most of the time, cheap floodplain land is not inhabited by wealthy people, but by people who cannot afford to live on top of the hill,” Watt said last week. The Government plans to establish a Disaster Preparedness Fund that will allocate up to A$200 million a year to disaster prevention and resilience programs.
