BBCcom_Content_Index_for_July_14_2021.txt
The flood warnings that save lives.txt
The cálculo probabilidade quinaflood warnings that save lives7 August 2025ShareSaveIsabelle Gerretsen, Jocelyn Timperley and Michael MaigaShareSaveGetty ImagesThe intensity and frequency of floods is increasing worldwide due to climate change (Credit: Getty Images)When floods hit, getting clear, timely warnings out to people becomes lifesaving, but too often these messages fail. The BBC asks disaster experts about how to get it right.In the Texan town of South Bend, people used to mark on a concrete pillar where floodwaters had reached in the past, disaster communications expert Keri Stephens recalls."It served as a reminder that water has been this high before. These visual warnings and community memories are very powerful," says Stephens, a professor at the University of Texas in Austin. Now, she says, the watermarks have faded.Texan communities have long had to live with the threat of flooding, which is becoming worse with climate change. When fatal flash flooding hit the state in 2025, questions were raised about whether adequate flood warnings had been provided. While warnings did go out, some residents said they did not understand the seriousness of the situation. For some in the hardest-hit areas, the warning alerts were delayed. Others said that they didn't receive any warnings at all, according to the New York Times.Alerting people about floods in time for them to act plays a critical role in saving lives and evacuating communities. Of course, warnings are only one part of protecting people from disasters: weather forecasting, long-term resilience measures and emergency responses are also incredibly important. But getting the messaging right about the risks and what to do is a crucial part of the puzzle. Sometimes all it takes is a shift in focus, says Stephens who has found that some people are more likely to respond to a call to protect their car than themselves. With climate change making floods more frequent and intense, the BBC looks at what it takes to get these messages right, and save lives in the process.Getty ImagesIt can be challenging to warn people about the danger they face due to flooding (Credit: Getty Images)Clear instructionsThe challenge of getting the right messaging can be particularly difficult for floods. "We're not taught in schools about responding to floods," says Stephens. "In the US, it is common to have 'stop, drop and roll' drills for fires, but we don't have drills for flood warnings."Rising floodsFloods are the world's most common natural disasters, and their number is increasing. From 1980 to 1999, there were 1,389 major flooding events; this almost doubled in the next 20 years to 2019. In the US, the National Weather Service (NWS) issues six different types of flood warnings, from "flash flood watch" to "flood warning". These reflect different types of risk at different severities.Existing flood warnings can be confusing, says Joseph Trujillo-Falcón, a professor in the department of climate, meteorology, and atmospheric sciences at the University of Illinois Urbana-Champaign. "If we're taking all this time trying to make sense of what [the warning] even means, it can delay protective actions and not encourage as many people to seek shelter when needed. We need more plain-language statements that really outline the hazard and get straight to the point." Research testing warning messages shows they are most effective if they include several critical components: a clear description of the hazard, information about the specific location, and concrete guidance on how and when to act. They also must come from what is seen as a credible source.Visual warnings and community memories are very powerful – Keri Stephens"We need to be more precise with our geography [in warnings], especially in areas with mixed topography," says Stephens. Messages should also make it clear that they are only being sent to communities at risk, rather than the entire region.Getty ImagesAlerting people about floods in time for them to act plays a critical role in saving lives (Credit: Getty Images)The key thing, Stephens adds, is for warnings to tell people whether they should evacuate or stay where they are. "One of the big challenges we have with floods is that when sirens go off, people don't know if they're supposed to shelter in place or evacuate," she says. "You must tell them an action at the end [of the warning]. Just saying 'You're in danger' or 'This is happening in your community'. People read that message and go, 'Ok, what do I do with this?'" The impact of floodsGlobally, roughly 5,000 people are killed each year in flooding events, and in the US, the yearly average is 127 people. But flooding events also cause lots of other disruption to people's lives: they destroy homes, businesses and crucial infrastructure, ruin financial prospects and can rob people of a life's worth of personal possessions. They can also have lasting impacts on health, spreading infectious diseases and cause post-traumatic stress disorder (PTSD).Psychologists at the University of Houston recently tested an update of a flood warning system available on a popular Houston weather blog. One hundred people living on the Gulf Coast were asked how likely they were to take protective measures, such as gathering supplies or charging phones, after being given a warning. The alerts for one group came from the previous colour-coded rating system which told them only the flood risk faced (for example, "1 green" was "street flooding only" and "5 purple" was "historic regional flooding"). The other group was given a new version with examples of how to act for each stage of flood risk, for example, "never drive into flooded roadways" or "be prepared to shelter in place for multiple days". People in the second group did a better job of planning for the storms, the researchers said.Targeted alerts But even if there are clear instructions about what to do, it's important that the type of communication is tailored to different users, says Liz Saccoccia, water security associate at the World Resources Institute, a non-profit based in Washington DC. "Women, disabled, elderly, different levels of literacy, and those without phone service or radio communication will need different communication methods," she says. The content of the message "also needs to be tailored to groups' specific risk tolerance", says Saccoccia. For example, Stephens, who is carrying out (as yet unpublished) research into flood communication in Texas, has found that the NWS warning phrase, "Turn around don't drown" doesn't tend to resonate with young men.In her focus groups, some young men responded to this message by laughing and saying: "I'm not going to die, I've got a big truck," Stephens says. "When we have a message [like turn around don't drown] that people don't feel applies to them, they're not going to take it seriously," says Stephens. In the US, men are much more likely to die in floods than women, according to a 60-year national analysis of flood fatalities. Men are more likely to drive through floodwater and more likely to exhibit risk-taking behaviour, the analysis found. But Stephens says the warning "Keep your car high and dry" does seem to appeal to young men. "I tested [this] message in groups and it worked beautifully," she says. Getty ImagesMultilingual warningsIn many parts of the US, multilingual warnings are also crucial, says Trujillo-Falcón, who researches these warnings."We have a very significant multilingual population in the United States, 67.8 million people speak a language other than English at home," he says. "That's one in five Americans." In a state like Texas, he adds, where there are a lot of Spanish-speaking communities, multilingual flood warnings can "be the difference between life and death". A 2022 study by Trujillo-Falcón and other researchers found that the urgency of weather warnings often gets lost in translation. US Spanish speakers were asked to indicate the urgency they felt when shown different Spanish words used in translations of weather "watch", "warning" and "advisory" alerts. They consistently rated "aviso", the translation of "warning" used by US organisations responsible for sending out alerts, as less urgent than many other alternatives. In fact, they found that "advertencia", the translation of "advisory", communicated more urgency than both the "watch" and "warning" translations.Community members and word of mouth can help disseminate crucial information in multiple languages, says Trujillo-Falcón. "They can be language brokers. We should depend on the community more, because not only are we getting the warnings out, but there's also increased trust."Getty ImagesIn flood-prone Peru, community participation has been life-saving (Credit: Getty Images)Word of mouthIn fact, again and again community connections have proven crucial in ensuring people act appropriately when floods and other disasters hit. This is especially important in rural areas which may be harder to reach via official channels.A 2021 review of flood warnings found that word of mouth warnings, delivered for example via door knocking, transmitted a greater sense of urgency and authority and made recipients more likely to follow recommended actions. More widely, speech-based warnings (face-to-face, via radio, TV or telephone) were more effective than sirens, text alerts, websites and social media. Bangladesh, one of the most disaster-prone countries in the world, has been especially praised for developing an advanced early warning system with relatively few resources. Its approach includes text messages, radio announcements and thousands of formal shelters which double up as schools and community centres. It also has a large number of volunteers – half of them women – who patrol streets with megaphones to disseminate the warnings and go door-to-door to help and encourage people to evacuate. (Read more about Bangladesh's trailblazing early warning system here).We should depend on the community more, because not only are we getting the warnings out, but there's also increased trust – Joseph Trujillo-FalcónIn Peru, climate change is worsening flood risk including due to glacial retreat and in 2023, devastating floods left over 800,000 people in need of assistance. In flood-prone regions community participation has been lifesaving, according to Miluska Ordo?ez, a risk management specialist at UK-based non-profit Practical Action, who spoke to the BBC in 2022. Several settlements along the Rimac watershed faced an unmistakable flood risk, she says, but were also resistant to the government's attempts to relocate them. Practical Action involved three of these communities in mapping flood risk and helped set up community flooding brigades which alert people via word of mouth. Forty brigade members helped evacuate hundreds of people when floods hit during Cyclone Yaku in March 2023, Ordo?ez says. Evacuating people at risk from floods is difficult to do with technology alone, she adds. While a community-led network broadcasts alerts via WhatsAppto at risk communities, it's people who have been engaged with, listened to and included in the creation and maintenance of warning systems who are the most responsive, Ordo?ez says. In most cases, she says, community leaders are men, and especially older men, but it's important to listen to younger people and women as well, which often includes adapting to their needs and schedules. "What has worked for me a lot is listening," says Ordo?ez.Overall, says Trujillo-Falcón, getting the word out through various mediums will always be incredibly important. "I do think that is the future of flood warning communication systems, that just as much as we're relying on these formal systems to warn us, we should depend on the community more," he says. "Because at the end of the day, we're here to help each other out."--For essential climate news and hopeful developments to your inbox, sign up to the Future Earth newsletter, while The Essential List delivers a handpicked selection of features and insights twice a week.For more science, technology, environment and health stories from the BBC, follow us on Facebook and Instagram. Extreme weatherEarthFuture PlanetClimateEnvironmentCommunicationPsychologyWaterNatural disasterScienceFeatures
