Nearly 350,000 moved because of floods in Rio Grande do Sul
More than half (53.2%) of households in areas affected by the 2024 floods in Rio Grande do Sul suffered some damage. Among homes in the hardest-hit areas, 11.7% were heavily damaged or destroyed. Nearly 350,000 people moved because of the climate disaster. Seven out of ten affected households (67.5%) had at least one person whose mental health was shaken.
The data is part of the Special Survey on the Floods in Rio Grande do Sul (PEERS), carried out by the Brazilian Institute of Geography and Statistics (IBGE), which provides a picture of the consequences for residents of 133 municipalities mapped as the most affected among the state’s 497 municipalities.
This is the first time IBGE has interviewed residents of regions hit by a climate disaster about its impact on their lives. The survey was inspired by studies of other climate disasters around the world, such as Hurricane Katrina in the United States in 2005.
“Unfortunately, climate disasters are occurring more and more often. Even with the difficulty of data collection, IBGE created a methodology to apply in surveys on environmental disasters,” says PEERS coordinator Juliana Vasconcellos.
In this survey, IBGE faced problems collecting the data, which was gathered entirely by telephone, but says the results are statistically reliable.
The group of 133 selected municipalities met criteria such as the declaration of a state of public calamity or emergency, depending on population size and the share of households in the most affected areas.
Under this methodology, the total number of households in the areas most affected by the floods was estimated at 2.328 million, while the total number of residents in the survey area was calculated at 6.333 million.
Based on the physical condition of households after the floods, 81,200 homes (3.5% of the total) were assessed as destroyed, while 190,200 were classified as heavily damaged (8.2%). As a result, 11.7% of homes reached the highest level of precariousness. By contrast, 46.8% of households suffered no damage.
Of the 6.333 million people in the affected areas, 24.9% lived in households whose overall living conditions at the time of data collection were worse than those experienced in the month before the floods. Of all residents, 66.8% lived in households with monthly income of up to R$5,000.
According to the survey data, 349,400 people (5.5% of residents) changed addresses because of the floods. The survey also found that 88% of households in the most affected areas experienced some form of disruption due to the climate disaster. The most frequent were interruptions in water and electricity supply (66.3%).
The survey also investigates consequences for personal life. The highest percentages were observed in the following situations: shaken mental health (67.5%); interruptions in social life or contact with family or friends (58.4%); and difficulty commuting to work, school, or day care (57.3%).
In the publication, IBGE acknowledges the problems faced during the collection phase. Only 18% of households in the survey sample (6,100 of 33,900 homes) completed the questionnaires.
“Telephone data collection has specific conditions; people are wary of answering calls. IBGE designed the sample size [of households] taking this non-response into account. Some cross-tabulations were not released because of a high coefficient of variation, and we had to aggregate certain data, but the survey is statistically reliable,” says study coordinator Juliana Vasconcellos.
With the exception of the Demographic Census, in which all households are visited, surveys are conducted using a sample of households whose profiles are similar to those of the total population. In this case, the sample reflects those affected by the 2024 floods in Rio Grande do Sul.
This survey, however, was conducted only by telephone, while others combine in-person interviews, which are the majority, with telephone interviews. The floods themselves also limited efforts to locate residents in the most affected areas. According to Vasconcellos, the survey’s pilot test had already indicated a high non-response rate.
To indicate possible differences between the sample results and the total population or households, statistical techniques estimate a coefficient of variation (CV). This coefficient is a measure of precision, presented as a percentage, indicating how much a given piece of information is subject to sampling error. The higher the percentage, the lower the precision of the data.
In PEERS, some indicators have a coefficient of variation of nearly 50%. All information in the survey, however, indicates the equivalent percentage. “We indicate in the table some imprecisions, where the use [of the data] should be handled with caution. But all of them are reliable,” says Vasconcellos.
Translation: Todd Harkin
