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Streamflow Measurement at TxDOT Bridges

What Was the Need?

Flash flooding is the leading cause of weather-related deaths in Texas. If we could predict ahead of time which rivers and streams will flood and make roadways impassable, we could greatly increase the safety of Texas motorists and emergency crews. One way to predict rising waters is through the National Water Model, which uses data from 550 gages in Texas to take measurements of streamflows. However, researchers needed to ensure that the model gives accurate forecasts of water levels—an urgent need, as 27,000 Texas bridges cross streams whose levels are measured by the National Water Model.

What's the Solution?

The Center for Water and the Environment (CWE) at the University of Texas at Austin, who originally worked with the National Weather Service to develop the National Water Model, were brought in to examine the feasibility of a broader streamflow measurement program on TxDOT bridges. For this pilot implementation project, the CWE team installed gages at 20 water crossings along Interstate Highway 10 (I-10) between San Antonio and Beaumont. These gages use radar to measure both the water elevation and velocity without the devices touching the water. Water velocity data are useful in the coastal zone, such as on I-10 in the Beaumont District, where all the gage sites have a stream bed elevation below sea level. The gages transmit water level and velocity data every 15 minutes through a cellphone connection. The CWE team developed a method to analyze any errors found in National Water Model forecasts. Applied to a test case in the Navidad river basin, the methodology shows promise for improving the flow forecasts for about 15 miles upstream and 30 miles downstream of a gage. Implementing real-time flow forecasts from the National Water Model creates a firm basis for flood planning over a wide area, improving flood response on and near the highway, and allows a proactive (rather than reactive) approach to managing road closures during flood events.

Research Benefits

The gages are portable and relatively easy to install on the bridge; potentially their installation could be folded into any future bridge repairs or upgrades throughout the TxDOT bridge system to create a far denser and thus more accurate network to detect rising waters. This project creates a foundation for regional flood risk assessment of the highway system to identify areas most likely to need road closures during flood events.

Project Number

5-9054-01

Status

Completed

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