A flood expert explains why the area’s floods can become so dangerous
Published
July 7, 2025 7:34PM (EDT)
rescue workers search near debris looking for any survivors or remains of people swept up in the flash flooding. (Photo by Jim Vondruska/Getty Images)” decoding=”async” fetchpriority=”high”/>
Search and rescue workers search near debris looking for any survivors or remains of people swept up in the flash flooding. (Photo by Jim Vondruska/Getty Images)
This article was originally published on The Conversation.
Texas Hill Country is known for its landscapes, where shallow rivers wind among hills and through rugged valleys. That geography also makes it one of the deadliest places in the U.S. for flash flooding.
In the early hours of July 4, 2025, a flash flood swept through an area of Hill Country dotted with summer camps and small towns about 70 miles northwest of San Antonio. At least 75 people died in Kerr County, and 10 girls from one camp were still unaccounted for, officials said on July 7. At least 19 deaths were reported in other counties.
The flooding began with a heavy downpour that sent water sheeting off the hillsides and into creeks. The creeks poured into the Guadalupe River.
A river gauge at Hunt, Texas, near the camp, showed how quickly the river flooded: Around 3 a.m. on July 4, the Guadalupe River was rising about 1 foot every 5 minutes at the gauge, National Weather Service data shows. By 4:30 a.m., it had risen more than 20 feet. As the water moved downstream, it reached Kerrville, where the river rose even faster.
Flood expert Hatim Sharif, a hydrologist and civil engineer at the University of Texas at San Antonio, explains what makes this part of the country, known as Flash Flood Alley, so dangerous.
What makes Hill Country so prone to flooding?
Texas as a whole leads the nation in flood deaths, and by a wide margin. A colleague and I analyzed data from 1959 to 2019 and found 1,069 people had died in flooding in Texas over those six decades. The next highest total was in Louisiana, with 693.
Many of those flood deaths have been in Hill County. It’s part of an area known as Flash Flood Alley, a crescent of land that curves from near Dallas down to San Antonio and then westward.
The hills are steep, and the water moves quickly when it floods. This is a semi-arid area with soils that don’t soak up much water, so the water sheets off quickly and the shallow creeks can rise fast.
When those creeks converge on a river, they can create a surge of water that wipes out homes and washes away cars and, unfortunately, anyone in its path.
Hill Country has seen some devastating flash floods. In 1987, heavy rain in western Kerr County quickly flooded the Guadalupe River, triggering a flash flood similar to the one in 2025. Ten teenagers being evacuated from a camp died in the rushing water.
San Antonio,