Australia's deadly floods, October 2022

 Townsville, Qld

1.Riverine floods are the most common form. The two main contrib­ut­ors to riverine flooding are heavy rainfall and the land’s capacity to absorb water. When the land is satur­ated, the excess water flows into river systems and pushes the overflow onto the adjacent low-lying areas.

2.Flash floods occur from short intense bursts of rainfall, as during a thunderstorm. They can be particularly dangerous in ur­ban areas where drainage systems cannot cope with the amount of water. As the water rises quickly, the drainage system may have insuffic­ient capacity or time to cope with the downpour. Alth­ough flash floods are generally localised, they may pose a signif­icant threat because of their short duration and unpredictability.

3.Coastal floods happen when a low-pressure system or strong onshore winds force sea levels to rise above normal levels, creating a storm surge that floods low-lying areas. All type of floods can be class­if­ied as minor, moderate or major bas­ed on their impact on communit­ies and infrastructure.

Floods occur all over Australia, however different types of floods are common in different regions. Location determines what type of flooding is likely to experienced: river, flash or costal flooding or a combination. In the extensive flat inland regions, floods may spread over thousands of square ks and last sev­eral weeks.

The damage from floods can be varied, extensive and far reach­­ing. The immediate impacts of flooding include loss of human life, long term damage to property, crop destruction and loss of live­stock. The ongoing emotional impact is often terrible, as are the em­otional st­ress and physical illness from waterborne diseases. Floods also dam­age power transmission and sometimes power gener­at­ion, which then has knock-on effects caused by the loss of power.

The 2022 flooding was caused by a low pressure system over Queens­land's southern coast that dragged in moisture from the Coral Sea in the north, raising it over the Queensland coastline. The low press­ure trough delivered the rainfall but an area of colder air higher in the atmosphere was drifting in, making the atmosphere unstable and permitting moisture to be lifted up and dropped as heavy rain. 

The 2022 eastern Australia floods were one of the nation's worst re­corded flood disasters that occurred in S.E Queensland and in­to coast­­al NSW. Brisbane suff­ered major flooding, as did the cities of Maryborough, Sunshine Coast, Gympie, Cab­oolture, Too­woomba, Ips­wich, Logan City, Gold Coast, Murwillumbah, Mullum­bim­by, Grafton, Byron Bay, Ball­ina, Lis­more, Central Coast and Sydney. Clearly as the system headed south, it turned into an East Coast Low near New South Wales/NSW’s Central Coast and Sydney. It will not surprise anyone that Sydney received more rainfall this October than any other October total in almost 170 years of record-keeping.

22 people so far have died in the 2022 floods. Across S.E Queens­l­and, 1000 schools were closed in response to the flood­ing, evac­uat­ions were urgent and the public had to avoid non-essential travel. Food shortages occurred across the region due to the ensuing supply chain crisis in outback Queensland. The flooding caused the ground across S.E Queensland and Northern NSW to become saturated and vul­nerable to even small amounts of rain.

While the amount of rain was less than the huge volumes seen in eastern states earlier in the year, the situation in the southern state of Victoria was made worse by the ground already being sat­ur­ated. Victoria had experienced its wettest Aug since 2010, and Sept rainfall was above average across most of northern Victoria. 

A low pressure system travelled east over the nation, bringing the rain which hit southern Australia throughout Oct. As torrential rain swelled many of Victoria's major waterways to flood level, tran­­s­port routes were cut, homes were inundated and communit­ies were isolated. Victoria's floods were particularly severe along the Goulburn, Loddon and Campaspe Rivers, and on the Murray River. The third yearly La Niña event in a row was an important driver of rain in spring and summer. But the Indian Ocean electric dipole was really the main cause of the recent inland crisis.

South of the mainland in Northern Tasmania, some of the most signif­icant flooding that they’ve had for years have subsided. But the wea­th­er system that pushed through in October has again lifted some of the northern river levels. And many of the catchments that were affected weeks ago have already received warnings that more rain was coming. Tas­manian residents in regions hit by recent floods are now preparing again as storm fronts move over the island state. Moderate flood warnings are in place to northern towns near Launceston, places already flooded.