Even before the devastating Central Texas floods that resulted in over 100 fatalities, Texas had already been the state with the highest number of flood-related deaths in the U.S. This can be attributed partly to its geographic features that can channel rainwater into lethal surges, as revealed by a long-term study.

Between 1959 and 2019, flooding claimed the lives of 1,069 individuals in Texas. This accounts for almost 20% of the 5,724 flood-related deaths recorded across the contiguous United States within that timeframe, based on a 2021 study published in the journal Water. This figure is approximately 370 more deaths than those reported in Louisiana, the state with the second-highest number.

Floods rank as the second leading cause of weather-related fatalities in the nation, next to heat, both in 2024 and across the past three decades. The National Oceanic and Atmospheric Administration reports an average of 145 deaths annually in the last ten years.

Other floods have turned deadly this year: Last month in San Antonio, 13 people died including 11 people who drove into water thinking they could get through, according to study author Hatim Sharif, a professor of civil and environmental engineering at the University of Texas at San Antonio who studies why people die in floods.

For several years Sharif has urged state and local officials to integrate better emergency action programs to use flood forecasts and save lives by alerting people and closing off vulnerable intersections where roads and water meet.

“I think in Kerr County, if they had an integrated warning system that uses rainfall forecasts to forecast real-time impacts on the ground, that could have saved many lives and could have also helped emergency crews to know which location would be flooded, which roads would be impassable,” Sharif said. “They could have taken action.”

The role of geography and terrain

Texas has so many deaths because of its geography, population and size, experts say. The area where the most recent deadly floods struck is known as flash flood alley because of hills and valleys.

“Steep, hilly terrain produces rapid runoff and quick stream rises, since the water will travel downhill at greater speed into rivers and over land,” said Kate Abshire, lead of NOAA’s flash flood services. “Rocky terrain can exacerbate the development of flash floods and raging waters, since rocks and clay soils do not allow as much water to infiltrate the ground.”

“Urban areas are especially prone to flash floods due to the large amounts of concrete and asphalt surfaces that do not allow water to penetrate into the soil easily,” she said.

Along with those hills, “you’ve got the Gulf of Mexico right there, the largest body of hot water in the entire North Atlantic most of the time,” said Jeff Masters a former government meteorologist who co-founded Weather Underground and now is at Yale Climate Connections. “So you’ve got a ready source of moisture for creating floods.”

Preventable driving deaths

Historically, many of the deaths were preventable across the nation and in Texas alike, according to experts. Masters said nothing illustrates that better than one statistic in Sharif’s study: 86% of flood deaths since 1959 were people driving or walking into floodwaters.

Nearly 58% of the deaths were people in cars and trucks. It’s a problem especially in Texas because of hills and low lying areas that have more than 3,000 places where roads cross streams and waterways without bridges or culverts, Sharif said.

“People in Texas, they like trucks and SUVs, especially trucks,” Sharif said. “They think trucks are tough, and that is I think a factor. So sometimes they use their big car or SUV or truck, and they say they can beat the flood on the street … especially at night. They underestimate the depth and velocity of water.”

Abshire said that not only do people ignore the weather service’s safety mantra, “Turn around, don’t drown,” but studies found that a number of these fatalities occur when people actively drive around barricades and barriers blocking flooded roads.

The latest Texas Hill Country flooding was less typical because so many of the deaths were in a camp where the water overtook the victims, not people going into the water, Sharif said. Only about 8% of flood deaths in the last 60 years happened in permanent homes, mobile homes or camping, according to the study.

The July 4th floods happened at night, a common time for flood deaths. More than half of deaths since 1959 have occurred at night, when it’s dark and people can’t see how much flooding there is or are not awake for the warnings, Sharif’s study found.

As far as demographics, about 62% of U.S. flood deaths were male, according to the study.

“Risk-taking behavior is usually associated with men,” Sharif said, adding that it’s why most fatal victims of car crashes are male.

___

The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.