Officials in Texas are under scrutiny for a string of refusals to fund early warning systems for flash floods in an area where sudden, intense rainfall is frequent.
Those measures could have included river gauges and warning sirens that could have alerted people that their lives were in imminent danger. The floods that raged down the Guadalupe River eight days ago killed at least 121 people, including at least 36 children.
But global experts in early warning systems said that there are few examples of places around the world that have mastered the choreography of forecasting and communication needed to prevent loss of life in extreme rain events. And in many cases, like in Texas this month, accurate forecasting alone is not enough to prevent calamity.
“Flash floods are the hardest kind of disaster to prevent,” said Erin Coughlan de Perez, who studies disaster risk management at Tufts University. She said that both rich and poor countries have grappled with funding for systems that ultimately either fail or create enough false alarms to erode public confidence.
For instance, in Valencia, Spain, a lack of sufficient warnings contributed to a catastrophe where more than 200 people died in flash floods last year. An alert system was in place, but was not activated until it was already too late.
“When the alert came, my grandpa had already drowned,” one resident told The Times.
“There’s a major ‘cry wolf’ issue because flash floods are so hard to predict,” Dr. Coughlan de Perez said. “And they are pretty infrequent in most places, so it’s hard to motivate investment. But of course, with climate change, they are also getting stronger and more common.”
One country that experts agree has done a better job than others is Japan.
Japan is among the world’s most disaster-prone countries, primed for earthquakes, tsunamis, typhoons and more. And the nation’s steep mountain ridges, fast-flowing streams and heavy rains make flash flooding a particular threat.
Yet heavy investment in storm infrastructure and advanced early warning systems have helped Japan significantly curb deaths from natural disasters.
Supercomputers, weather satellites and radar feed advanced weather forecasts and warnings that are then beamed within minutes to local television and radio networks, a network of loudspeakers, and cell phones. (J-Alert, an early warning system primarily used for quakes, tsunamis and North Korean missile alerts, but also for the most serious extreme weather events, is designed to send out nationwide alerts within seconds.)
Local municipalities are responsible for issuing evacuation orders and other directives, accompanied by the swift opening of evacuation centers at schools and other public buildings, which are supplied with futons and other emergency provisions.
But tragedies still occur, especially as climate change fuels more extreme weather. In 2020, 14 people perished in widespread flooding on the southern island of Kyushu after a botched evacuation at a nursing home, reflecting the challenges facing older populations.
Flooding in urban areas is also on the rise: In recent days, torrential rain in Tokyo inundated roads and disrupted train services. (No casualties have been reported.)
And the Japanese public risks becoming a victim of the country’s success in addressing disasters, said Yukiko Takeuchi, a professor at Kumamoto University on Kyushu who specializes in regional disaster prevention. In a survey published in 2024, more than half of all municipalities said only 10 percent of residents complied with recent evacuation orders. For almost a quarter of municipalities, the evacuation rate was less than 1 percent.
“People who’ve been shielded from past disasters tend to assume they’ll be fine,” she said. “Then they risk getting stranded.”
The United Nations has set a target for the entire world to be covered by early warning systems for all kinds of natural disasters by the end of 2027. Right now, only about half of the world’s countries have implemented such systems, though that represents a near-doubling of the number over the past decade.
In Bangladesh, a low-lying country that sees some of the highest rainfall in the world, officials have been trying to improve their flash flood early warning systems for a quarter of a century, said Shampa, a hydrologist at the country’s Institute of Water and Flood Management, who goes by one name.
“We are able to tell people about three to five days ahead but so far still more than half of our warnings end up being false alarms,” she said.
The majority of the country’s flash floods originate across the border from hills in India, necessitating close international cooperation. The government works with mosques, local community organizations and telecom providers to get urgent messaging out in as many ways as possible.
“But relying on text messages is hard because heavy rain often causes power cuts and people’s phone are not charged,” Shampa said. “And if they get the message, do they understand what a certain level or velocity of river means? Or what it means for their land in particular?”
Researchers in wealthier countries have partnered with governments in poorer ones, like Uganda, to try to expand the kind of high-tech systems that have a higher success rate.
Liz Stephens, a professor in the meteorology department at the University of Reading in England, said that researchers were working in Uganda, Nepal and elsewhere to use satellite monitoring to predict flash floods.
It was necessary in Uganda because some flash floods were so strong that rivers carried boulders along with them, crushing river gauges that had been installed.
And in Nepal, where some flash floods are caused by the collapse of lakes held back by glaciers, work is underway to understand better how those collapses are triggered. Last week, floods in Nepal washed away the main bridge connecting the country to China.
Most early warning systems are put into place only after disasters strike, Dr. Coughlan de Perez said. And responses often assume that the next disaster will look like the last, but with climate change intensifying, that is a shaky assumption.
“We’re driving forward while looking in the rearview mirror,” she said.
Max Bearak is a Times reporter who writes about global energy and climate policies and new approaches to reducing greenhouse gas emissions.
Hiroko Tabuchi covers pollution and the environment for The Times. She has been a journalist for more than 20 years in Tokyo and New York.
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