This article has been republished with authorization from The Conversation, a digital platform dedicated to sharing the latest academic insights.

The Texas Hill Country, renowned for its picturesque scenery with meandering shallow rivers and rugged valleys, is also one of the most hazardous locations in the United States for sudden, severe flooding.

On the early morning of July 4, 2025, a devastating flash flood struck the Hill Country region, about 70 miles northwest of San Antonio, affecting summer camps and small communities. In Kerr County alone, the flood claimed the lives of at least 75 individuals, and 10 girls from a local camp were reported missing as of July 7. Additionally, several other fatalities were reported in surrounding counties.

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The flood initiated from a torrential downpour, causing runoff from the hills to surge into streams and further into the Guadalupe River.

A river gauge in Hunt, Texas, close to the affected camp, recorded the rapid rise of the river. According to the National Weather Service, at around 3 a.m. on July 4, the Guadalupe River’s water level was rising by approximately one foot every five minutes. By 4:30 a.m., it had surged over 20 feet. As the floodwaters advanced downstream, they reached Kerrville, escalating even faster.

Hatim Sharif, a hydrologist and civil engineer at the University of Texas at San Antonio, explains that this area, known as Flash Flood Alley, is particularly prone to such disasters.

What Makes Hill Country Highly Susceptible to Flooding?

Texas is the leading state in flood-related fatalities in the nation, with a significant margin. Research analyzing data from 1959 to 2019 revealed that 1,069 people died due to flooding in Texas during this period, followed by Louisiana with 693 deaths.

Many of these fatalities occurred in Hill County, part of the notorious Flash Flood Alley, which extends from near Dallas down to San Antonio and westward. The region’s steep hills cause water to flow rapidly during heavy rains, and the semi-arid soil does not absorb water well, leading to quick runoff and swift rises in creek levels.

When these creeks meet a river, they can generate a powerful surge of water capable of destroying homes, sweeping away vehicles, and tragically, people.

Past events include a tragic incident in 1987, when intense rainfall in western Kerr County led to a rapid rise in the Guadalupe River, resulting in a deadly flash flood that killed ten teenagers being evacuated from a camp. Another recent disaster struck San Antonio on June 12, 2025, when a flash flood claimed the lives of 13 people whose vehicles were swept away by the swiftly rising waters of an overflowing creek.

Why Does the Region Experience Intense Rainfalls?

One major factor contributing to the intense rainfalls in Hill Country is the Balcones Escarpment, a geological fault line marked by cliffs and steep hills. Warm air from the Gulf of Mexico ascends the escarpment, condenses, and releases significant amounts of moisture, which then rapidly descends the hills, filling the streams and rivers below.

As temperatures climb, the atmosphere can retain more moisture, further elevating the risk of heavy downpours and subsequent flooding. This effect also contributes to flash flooding in San Antonio, where extensive paved surfaces and inadequate drainage systems exacerbate the situation.

Enhancing Safety Against Flash Floods

Understanding the mechanics of flash floods and the rapidity with which floodwaters can rise is crucial. In arid regions, even dry or shallow creeks can quickly become deadly torrents following heavy rain, so awareness and vigilance are key.

Enhanced flood forecasting can also aid in preparedness. Probabilistic forecasting, which provides a range of potential rainfall scenarios, can help authorities anticipate the worst and plan accordingly. A scientific approach that connects rainfall forecasts to local impacts—like streamflow, flood depth, and water velocity—could also support effective emergency responses, such as timely evacuations and road closures.

It is particularly important for drivers to understand that even one to two feet of moving water can carry away a vehicle. Despite the ruggedness attributed to trucks and SUVs, they are not immune to being overturned and swept away by fast-moving floodwaters.

Authorities could also intensify efforts to barricade roads when flooding is likely, preventing drivers from entering dangerous areas. Our findings indicate that 58% of flood deaths in Texas over the last six decades involved vehicles, often during conditions of poor visibility like those during the early hours of June 12 in San Antonio, when vehicles were caught by rapidly rising waters from a nearby creek.

This article was initially published on The Conversation. Read the original article.