While parts of Texas have a reputation for drought and dryness, a large stretch of the state has been deemed “Flash Flood Alley.”
The area follows Dallas-Fort Worth along the I-35 corridor through Austin and San Antonio in the Hill Country and curves toward Del Rio in southwestern Texas.
Flash flooding is a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event, according to the National Weather Service.
This type of flooding can be dangerous and deadly, killing more people than many other weather threats combined.
The region is prone to flash floods because of its steep terrain, shallow soil and intense rainfall rates, according to the Texas Water Development Board. The heavy rain can turn into walls of fast-moving water and can be destructive.
These factors, especially in the Balcones Escarpment landscape in Central Texas, make Flash Flood Alley one of the most flood-prone regions in North America.
The alley, which includes some of the fastest-growing cities in the nation, could have an increased risk of flash flooding in the future as development continues adding impermeable surfaces to the landscape, creating more runoff.
Texas published its first-ever State Flood Plan in August 2024, which combines findings from 15 river-basin-based regional flood plans and makes legislative and floodplain management recommendations to guide flood control policy. The ultimate goal is comprehensive planning to reduce flood risk and take a broad look at flood hazard.
This reporting is part of the Future of North Texas, a community-funded journalism initiative supported by the Commit Partnership, Communities Foundation of Texas, The Dallas Foundation, the Dallas Mavericks, the Dallas Regional Chamber, Deedie Rose, the McCune-Losinger Family Fund, The Meadows Foundation, the Perot Foundation, the United Way of Metropolitan Dallas and the University of Texas at Dallas. The News retains full editorial control of this coverage.