Brays project cut flooding risk, county says
District’s new maps expected to show area facing probability of such dangers has shrunk
Harris County officials expect new floodplain maps to show that a major Brays Bayou flood control project has reduced risks in recently inundated neighborhoods such as Meyerland and Bellaire.
The county Flood Control District’s update is expected to reflect a considerable reduction of Brays Bayou’s floodplain because of wider and deeper channels and detention ponds.
That does not mean homes removed from the floodplain will never flood. A significant amount of rain in the right place, and for the right amount of time, would put any of the county’s roughly 4.4 million residents at risk.
The revised maps are part of a broader effort that began more than six years ago to better understand how many people face the most danger from floodwaters in different parts of a rapidly changing county.
“We produce the maps to see what the risks are,” said Ataul Hannan, planning division director for the flood control district. The Brays Bayou floodplain map update began in October and is expected to be finished by 2021.
While floodplain maps have existed since the late 1960s, Harris County’s first comprehensive maps weren’t developed until 2007. That’s when a multi-year, $32 million overhaul of flood control data and practices concluded following the devastation of Tropical Storm Allison in 2001.
The effort showed that many earlier maps were not accurate. It prompted the flood control district to begin routinely reviewing floodplains.
Revised maps can provide a financial benefit to owners of homes along the county’s bayous, said Matt Zeve, chief operating officer for the district. Living in a 100-year floodplain — an area that would be flooded if the
bayou received a storm so severe that it occurs once every 100 years — requires homeowners to pay more for flood insurance; removing the floodplain designation lowers the premiums.
In May 2016, the district completed the remapping of Sims Bayou in southeast Harris County after a 25-year, nearly $400 million project widened and deepened parts of that bayou.
The new maps removed 4,400 homes and businesses from the floodplain, according to the district. Once the Brays Bayou project is completed, the district estimates that downstream of Beltway 8, 15,000 homes and business will be removed from the 100-year floodplain.
The district is also working on remapping White Oak Bayou’s floodplain, an effort that began in October 2015 and is expected to be completed by 2020.
Tom Ballestero, director of the University of New Hampshire’s Stormwater Center, said there are many benefits to remapping floodplains, especially in an area like Houston that is constantly changing due to private development and the construction of major flood control projects.
“The landscape isn’t static,” Ballestero said.
He said climate change has caused fluctuations in precipitation rates across the country, affecting how much water flows into bayous and creeks and how much would spill out in a severe storm.
Improved technology could refine how floodplains are measured. This is particularly important in the flat Houston region, where just inches of floodwaters can ruin homes.
Ballestero said understanding where floodplains begin and end could also help guide future development.
Across the country, he said, cities and counties discourage building homes or preserving homes in floodplains.
In Meyerland, where recent storms have repeatedly inundated hundreds of homes, people will feel more confident buying a house that’s no longer in a floodplain, said Ed Wolff, president of Beth Wolff Realtors Real Living, who lives and markets homes in the area. For some prospective homebuyers, Wolff said, floodplains are deal-breakers.
Wolff said his home, which flooded during the Memorial Day 2015 floods, will likely be removed from the floodplain because of the project along Brays Bayou. But enough rain, he said, will cause floods anywhere.
“You’re really looking at a difficult prospect to be in Houston anywhere and think that you don’t have the potential for flooding,” he said.