From the FloodWorks website for the Emergency Operations Center.

The San Antonio River and its feeder creeks and tributaries have become an invaluable environmental and economic asset for San Antonio over the past decade. Commercial and residential development near the river is booming and on some weekend afternoons the Mission and Museum Reaches are almost too crowded.

But the river, like all rivers, is also an unpredictable force of nature. Casualties of human life and private and public property are too often left in the aftermath of a flood. San Antonio is no stranger to such devastation.

By linking rainfall radar data from the National Weather Service and other models, FloodWorks flood forecasting software recently implemented by the San Antonio River Authority (SARA) and the San Antonio Emergency Operations Center (EOC) could give emergency responders up to 24 hours of lead time to proactively prepare for floods.

Bexar County Flood Warning System on FloodWorks.
Bexar County Flood Warning System on FloodWorks.

“Before, it was all reactive,” said Russell Persyn, SARA’s watershed engineering manager. “Now we can simulate storms and structure resources where we know there will be issues.”

Most injuries and fatalities occur during the ramp-up of a flood, when people are caught off-guard, Persyn explained. The new technology, with a user-friendly interface and near real-time data simulations at the EOC located at Brooks City Base, allows the San Antonio Fire Department (SAFD) to deploy to neighborhoods or roadways where they are needed most.

FloodWorks Addressing a Real Need

“This is going to save lives,” said Fire Chief Charles Hood. “Not only help save citizens’ lives but also the lives of our first responders … swift water rescues (while not frequent) are the most dangerous.”

At the SARA Board meeting Wednesday, Hood relayed the story of a woman who was trapped in her car on a flooded road. Three firefighters went in after her and were able to break the window, but the vehicle turned over, flipping their boat. They were unable to save her, but managed to swim to safety.

From left: Fire Chief Charles Hood, SARA Engineer Wayne Tschirhart, and Russell Persyn, SARA's watershed engineering manager explain how the FloodWorks system works to the SARA Board.
From left: Fire Chief Charles Hood, SARA Engineer Wayne Tschirhart, and Russell Persyn, SARA’s watershed engineering manager explain how the FloodWorks system works to the SARA Board. Photo by Iris Dimmick.

Hood said he is confident that advanced warning could change the outcome of many scenarios like this.

“We can’t do it alone and we can’t do it without partnerships,” like this one with SARA and EOC, he said.

The SARA Board approved the purchase of FloodWorks for $2.1 million which includes the pilot program on Salado Creek initiated three years ago that provided “proof of concept” for full implementation, Persyn said. Yearly software maintenance costs of $20,000 have been allocated by the City through the EOC budget. 

FloodWorks allows SARA to monitor flood-prone areas including more than 183 creek and river miles and more than 140 low-water river crossings in Bexar County.

FloodWorks' points of interest map.
FloodWorks’ points of interest map.

Striking the right balance between deploying resources as quickly as possible and waiting to gather enough accurate data to determine where they should go will be the key to the operation, Persyn said. FloodWorks also allows for officials to save and analyze flood patterns. For instance, when each neighborhood or road floods at different water levels, that data will be stored for use in the next flood, so first responders can predict which places will need resources first or at all.

The system has three levels of warning: watch, minor, and major. The FloodWorks interface provides detailed floodplain maps and graphics with water surface levels, flows, velocities, and – in some cases – water depth.

A floodplain map produced by FloodWorks software.
A floodplain map produced by FloodWorks software.

SARA Board members and staff began thinking about finding a more advanced flood forecasting solution around 2005 when the Federal Emergency Management Agency (FEMA) required an update to the four-county basin including Bexar, Wilson, Karnes and Goliad counties.

After that $16.2 million modeling project, the board decided to take full advantage of the data and take it a step further, Persyn said. That’s when they came across United Kingdom-based FloodWorks system which has been used in London, Belgium, Ireland, and Egypt.

“It’s really to the core of our mission to provide flood protection,” said Sally Buchanan, SARA Board chair.

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Iris Dimmick

Iris Dimmick

Senior Reporter Iris Dimmick covers public policy pertaining to social issues, ranging from affordable housing and economic disparity to policing reform and workforce development. Contact her at