The “Flash Flood Alley” of Hill Country
Texas’ Hill Country region lies within a notorious area known as the “flash flood alley,” explains Hatim Sharif, a hydrologist at the University of Texas in San Antonio.
Warm air from the Gulf rises over the Balcones Escarpment—a steep line of hills and cliffs arching southwest from Dallas. As it cools, the air releases torrents onto thin soils that quickly give way to rocky bedrock. Subsequently, the runoff flows through a dense network of arroyos.
“The water level will rise very, very quickly—in minutes or hours,” Sharif told AFP. “The first hours of July 4 demonstrated this.”
By 3 AM local time, a gauge near Mystic Campground in Hunt showed the Guadalupe River rising nearly 30 centimeters every five minutes. By 4:30 AM, the river’s level had surpassed 6 meters, according to data from the National Weather Service (NWS).
This was enough water to sweep away people, vehicles, and buildings. Shortly after 1 AM, the NWS issued an alert, but most campers were asleep. Phones were prohibited, and coverage was spotty, while darkness made escape routes unclear.
Sharif advocates for using hydrological forecasts that translate rainfall into probable river levels.
“Rainfall should translate to runoff,” he says. “If you get 25 centimeters, what will the river level be?”
Summer camps have long attracted visitors to the region for their natural beauty. However, with rising risks, Sharif warns that treating these places as safe or permanent havens is not prudent.
“We Need to Adapt”
A warmer atmosphere retains more humidity, fostering downpours.
According to a recent ClimaMeter analysis, the weather conditions preceding the floods—which recorded more than double the monthly average precipitation in a single day—cannot be explained solely by natural variability.
“Climate change is already affecting us, so we need to adapt,” says Mireia Ginesta, a climatologist at the University of Oxford and co-author of the research, funded by the European Union and France’s National Center for Scientific Research (CNRS).
“We also need to reduce our emissions and ensure adequate funding for forecasting services and climate change research overall,” she added.
This call comes as weather services, along with other agencies, have experienced deep staff cuts under Republican President Donald Trump’s administration.
Experts emphasize, however, that NWS meteorologists performed admirably under the circumstances.
Lack of Alert System
For years, Kerr County commissioners—the hardest-hit—considered flood warning sirens and digital alerts to replace the informal practice of campground staff communicating by radio and warning other shelters.
Minutes from a 2016 meeting show officials dismissed a feasibility study as “a bit extravagant,” suggesting sirens would mainly aid tourists and approved word-of-mouth.
“The idea of our beautiful Kerr County having these damn sirens blaring in the middle of the night makes me want to drink to endure it,” Commissioner H.A. Buster Baldwin reportedly said.
Following the disaster, Nicole Wilson, a San Antonio mother nearly sending her daughters to Mystic Campground, launched a Change.org petition urging Governor Greg Abbott to approve a modern alert system.
“Five minutes of that siren could have saved every one of those children,” she told AFP.
Key Questions and Answers
- What is the “flash flood alley” of Hill Country? It’s a region in Texas where warm air from the Gulf rises over the Balcones Escarpment, causing rapid flooding due to thin soils quickly giving way to rocky bedrock.
- How does climate change contribute to the floods? A warmer atmosphere retains more humidity, leading to heavier downpours. The recent ClimaMeter analysis suggests that natural variability alone cannot explain the extreme precipitation during these floods.
- Why didn’t warning systems prevent the tragedy? Kerr County commissioners considered flood warning sirens and digital alerts but deemed them unnecessary, favoring informal communication methods.
- What measures can be taken to improve flood preparedness? Experts recommend using hydrological forecasts that translate rainfall into probable river levels and implementing modern alert systems.
