Texas Hill Nation is understood for its landscapes, the place shallow rivers wind amongst hills and thru rugged valleys. That geography additionally makes it one of the most deadliest puts within the U.S. for flash flooding.
Within the early hours of July 4, 2025, a flash flood swept via a space of Hill Nation dotted with summer time camps and small cities about 70 miles northwest of San Antonio. Greater than 130 folks died within the flooding. Nearly all of them had been in Kerr County, together with greater than two dozen women and counselors at one summer time camp, Camp Mystic. Dozens extra folks had been nonetheless unaccounted for every week later.
The flooding started with a heavy downpour, with greater than 10 inches of rain in some spaces, that despatched water sheeting off the hillsides and into creeks. The creeks poured into the Guadalupe River.
A river gauge at Hunt, Texas, close to Camp Mystic, confirmed how briefly the river flooded: Round 3 a.m. on July 4, the Guadalupe River used to be increasing about 1 foot each and every 5 mins on the gauge, Nationwide Climate Provider knowledge presentations. By way of 4:30 a.m., it had risen greater than 20 ft. Because the water moved downstream, it reached Kerrville, the place the river rose even quicker.
Flood professional Hatim Sharif, a hydrologist and civil engineer on the College of Texas at San Antonio, explains what makes this a part of the rustic, referred to as Flash Flood Alley, so bad.
What makes Hill Nation so liable to flooding?
Texas as an entire leads the country in flood deaths, and via a large margin. A colleague and I analyzed knowledge from 1959 to 2019 and located 1,069 folks had died in flooding in Texas over the ones six a long time. The following best overall used to be in Louisiana, with 693.
Lots of the ones flood deaths had been in Hill County. It’s a part of a space referred to as Flash Flood Alley, a crescent of land that curves from close to Dallas all the way down to San Antonio after which westward.
The hills are steep, and the water strikes briefly when it floods. It is a semi-arid space with soils that don’t take in a lot water, so the water sheets off briefly and the shallow creeks can upward thrust rapid.
Flash Flood Alley is the sunshine inexperienced crescent. The background colours display the slope of the land, with purple the sharpest upward thrust.
Zhongyu Han and Hatim Sharif, GIS Utility: Flood Possibility Control, 2020
When the ones creeks converge on a river, they may be able to create a surge of water that wipes out houses and washes away vehicles and, sadly, somebody in its trail.
Hill Nation has observed some devastating flash floods. In 1987, heavy rain in western Kerr County briefly flooded the Guadalupe River, triggering a flash flood very similar to the only in 2025. Ten youngsters being evacuated from a camp died within the speeding water.
San Antonio, on the japanese fringe of Hill Nation, used to be hit with a flash flood on June 12, 2025, that killed 13 folks whose vehicles had been swept away via prime water from a fast-flooding creek close to an interstate ramp within the early morning.
Why does the area get such robust downpours?
One reason why Hill Nation will get robust downpours is the Balcones Escarpment.
The escarpment is a line of cliffs and steep hills created via a geologic fault. When heat air from the Gulf rushes up the escarpment, it condenses and will sell off a large number of moisture. That water flows down the hills briefly, from many alternative instructions, filling streams and rivers beneath.
As temperature upward thrust, the hotter surroundings can dangle extra moisture, expanding the downpour and flood chance.
A excursion of the Guadalupe River and its flood chance.
The similar impact can give a contribution to flash flooding in San Antonio, the place the massive quantity of paved land and loss of up to date drainage to regulate runoff provides to the chance.
What will also be performed to enhance flash flood protection?
First, it’s necessary for folks to grasp why flash flooding occurs and simply how briskly the water can upward thrust and waft. In lots of arid spaces, dry or shallow creeks can briefly refill with fast-moving water and turn out to be fatal. So folks must pay attention to the dangers and be aware of the elements.
Making improvements to flood forecasting, with extra detailed fashions of the physics and water speed at other places, too can lend a hand.
Probabilistic forecasting, as an example, can give a spread of rainfall situations, enabling government to arrange for worst-case situations. A systematic framework linking rainfall forecasts to the native affects, similar to streamflow, flood intensity and water speed, may additionally lend a hand decision-makers put in force well timed evacuations or street closures.
Training is especially very important for drivers. One to 2 ft of shifting water can wash away a automotive. Other people might assume their vehicles and SUVs can undergo anything else, however fast-moving water can turn a truck and lift it away.
Officers too can do extra to barricade roads when the flood chance is prime to stop folks from using into hurt’s method. We discovered that 58% of the flood deaths in Texas during the last six a long time concerned cars. The typhoon on June 12 in San Antonio used to be an instance. It used to be early morning, and drivers had deficient visibility. The vehicles had been hit via fast-rising floodwater from an adjoining creek.
This text, firstly printed July 5, 2025, has been up to date with the demise toll increasing.
