Some 41 people have drowned (including three missing presumed dead (mpd)) over the 2021–22 La Niña period November 2021 to 12 May 2022 (at time of writing) from floods across south-east Queensland (QLD), northern New South Wales (NSW), Greater Sydney and Victoria (VIC).
During La Niña episodes, interactions between ocean and atmosphere act to increase the chance of rain to northern and eastern Australia. November 2021 was Australia’s wettest on record. The tail end of the 2020–21 La Niña episode brought extreme rain events and associated flooding to the east coastal regions and resulted in three deaths in NSW and one in QLD (March 2021).
A previous series of consecutive La Niña episodes, 2010–11 and 2011–12, witnessed very heavy rain, especially in QLD, over 2010–11. A total of 48 flood deaths occurred from August 2010 to June 2011: three in VIC, four in NSW and 41 in QLD.
The 2021–22 La Niña episode
In this current La Niña episode (as at 12 May 2022), there were two deaths in VIC, 15 (incl. one missing presumed dead (mpd)) in NSW and 24 (incl. two mpd) in QLD. The age ranges have varied from 10–14 to 80–84, with the most deaths occurring in the 50–54 age group (n=7; 17%). A total of 28 males (68%) and 13 females (32%) died.
Two-thirds of the deaths (68%; n=28) were due to cars driving through and/or being engulfed by floodwaters (not shown). All of the victims who were in a house that was engulfed by floodwaters or mudslides (10%; n=4) occurred in the Northern Rivers region of NSW in Feb-Mar 2022.
In most cases, the reason for the activity at the time of death was known (not shown) but for some it was not – e.g. of the 28 who died due to their car being washed away by floodwaters (Figure 1), 16 entered the floodwaters deliberately, three were taken by surprise (by a sudden ‘wave’ of floodwater), four were passengers (therefore, it was another’s decision; this decision was to deliberately enter floodwaters in at least three cases) and this data was unknown for another five.
A decade of flood deaths
PerilAUS, Risk Frontiers’ database of natural hazard occurrences and impacts in Australia, has data on the circumstances surrounding deaths back to 1788 but with best records from 1900. PerilAUS was queried for flood deaths from the 2011 financial year (FY: 1 July 2010 to 30 June 2011) to 12 May 2022. In most of the charts below, the data is divided into deaths from the two most fatal years (FY2011 and FY2022) and deaths from all other years.
At least 168 flood deaths (including five mpd) have occurred in Australia from FY2011 to FY2022 (Table 1), 421 (25%) of which occurred during FY2022 and 48 (29%) in FY2011.
Most flood deaths have occurred in QLD (n=96; 57%), followed by NSW (n=48; 29%) but, in FY2011, a much greater percentage of deaths, 85% (n=41), occurred in QLD. In FY2022, 57% (n=24) of deaths occurred in QLD, 38% in NSW and 5% in Victoria.
Of the 168 total deaths, 120 (71%) were male and 48 (29%) female. In FY2022, the relative percentages were similar: 29 (69%) male and 13 (31%) female. In FY2011 the ratios were closer together: 28 (58%) male and 20 (42%) female (not shown).
The most common age range was 60–64 years (n=16; 10%), then 65–69 and 40–44 (both n=14; 8%), with deaths spread fairly evenly over most age ranges (not shown). The normalised2 age ranges (Figure 1) show those from 60 to 64 years and above as overrepresented.
Half of all deaths (n=86; 51%) occurred in or near a vehicle that was washed away (Figure 2). Another 14% of deaths (n=24) took place inside or near a house that was flooded or collapsed due to floodwaters or rain-induced landslides.
Figure 3 shows that 96 (57%) of decedents deliberately entered floodwaters and 41 (24%) either had no warning or were taken by surprise, either by the event or by the suddenness and/or intensity (height) of the event. In 11 (7% of) cases, it was another’s decision: this relates to passengers in cars and, in this category, 7 (4% of) cases were deliberately driven into floodwaters. Some 7 (4% of) cases were decision-impaired: i.e., the decedents were very young, mentally incapacitated, intoxicated or otherwise unable to make decisions.
Most commonly, the reason behind the activity being carried out was to attain a destination (n=67; 40%), followed by partaking in recreation (n=29; 17%) (not shown). Another 13 (8%) had mobility issues, 10 (6%), even though able, were overwhelmed by floodwaters and 10 (6%) were at work or en route to work.
The PerilAUS record shows that the current focus of emergency managers for those most at risk of dying in a flood should be:
- Males (71% of fatalities)
- Persons living or travelling in Queensland (57%) or NSW (29%)
- Persons who attempt to drive through floodwaters (51%)
- Persons who deliberately enter floodwaters, either to drive through, recreate in or other (57%)
- Persons aged 60+ (38% of fatalities)
- Persons who enter floodwaters to attain a destination (40%)
- Persons, especially the elderly and less mobile, whose house is situated at risk of major flooding (14% of fatalities)
The total of 41 deaths for the 2021/22 La Niña season to 12 May 2022 (42 for FY2022 in total) is tragically high but could have been much worse, were it not for the efforts of professional and volunteer rescue personnel, and the ad hoc and organised actions of the general public: it is a credit to all that the death toll was not much greater.
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1. FY2022 shows 42 deaths, not 41, as one death occurred July 2021 – before the La Niña period commenced
2. Normalisation – viewing fatality numbers against a background population of the particular group of interest (in this case, age range) – enables the comparison of fatalities over time and location, by taking into account any changes in population.