The last few months have shown the dramatic swings that have long been a staple of Texas weather.
Since Sept. 1, DFW Airport has seen 15.95 inches of rainfall, leading to deadly flash flooding and water rising in places where it hadn’t been seen before.
For Dallas-Fort Worth, more than 23 of the 38 inches that have fallen this year occurred in just two months — February and September.
It has led to questions in Fort Worth, Arlington and Everman about the impacts of new development and how effective stormwater management has been in many North Texas cities.
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The cycle of flood-drought-flood also gives more fuel to the perception of Texas as a climate of extremes.
“I think that’s basically the story of Texas climate — we get more variability than other places in the United States or the rest of the world for that matter,” said Texas A&M state climatologist John Nielsen-Gammon.
Statewide, the three wettest months on record have taken place in the last three-and-a-half years.
“It could be evidence of a trend of more extreme monthly rainfall,” Nielsen-Gammon said. “There has been a general upward trend of a 10 percent increase in overall rainfall over the last century.”
But can you blame heavier rainfall on climate change? That’s a far more tricky proposition.
“In Texas, the computer models aren’t anywhere close to unanimous on the impact of climate change on rainfall,” Nielsen-Gammon said. “They tend to project a decrease rather than an increase.”
But if the climate warms, it could make the drought-flood cycle even more extreme with droughts and floods being even more intense.
“It’s important for planners to factor in a margin of error because climate change may lead to more extreme flooding,” Nielsen-Gammon said.
Fort Worth’s stormwater problems
Fort Worth officials say they don’t have data to know if storms are worsening, but they do know the stormwater system is out-of-date in many older neighborhoods.
With about $10 million a year for improvement projects, the stormwater department is limited in what it can work on, Ranjan Muttiah, a senior stormwater engineer, said while discussing the city’s flash flood alert system.
“That’s not a lot of money to resolve systemic problems,” Muttiah said.
The department frequently looks to other projects — utility or road improvements — that can include stormwater enhancements.
Parker Henderson Road along Prairie Dog Park in southeast Fort Worth frequently floods in a low area, Muttiah said. This spring a culvert will be added when the road is repaved. Small projects like that help mitigate flooding, but Muttiah said the official list of stormwater system improvements approaches $1 billion dollars.
Flash floods have worsened across Tarrant County.
West of Fort Worth, Marys Creek was one area that didn’t experience serious problems in the latest round of flooding — but it’s one of the biggest areas of concern for future development.
The creek runs from Parker County through Benbrook and Fort Worth before dumping into the Clear Fork of the Trinity River near Southwest Boulevard.
A 2013 U.S. Army Corps of Engineers study showed the 100-year flow for Marys Creek from 32,000 cubic feet per second to 42,000 cubic feet per second by 2055 because of development upstream. The levees along the Clear Fork can handle flows of 75,000 cubic feet per second, which is considered far greater than a 100-year flood, said Rachel Ickert, Tarrant Regional Water District’s water resource engineering director.
“It’s an area of interest to us,” Ickert said. “It’s mostly unregulated. There’s not a reservoir on that reach. There’s nothing to stop that flow.”
The North Texas Council of Governments is spearheading a study, largely funded by FEMA, which will look at the impacts of development on a 17-mile stretch of the creek. Parker County, Tarrant County, Fort Worth, Benbrook and TRWD are also kicking in funds for the study, said Edith Marvin, director of Environment and Development at the Council of Governments.
The study could start in early 2019 if all of the interlocal agreements work out.
“It’s not a given that results will end up on the FEMA flood plain maps but it is encouraged,” Marvin said. “It becomes the property of the municipality or county that helped pay for it.”
They have also been working to educate counties that the state water code allows them to enforce stormwater rules on developments in unincorporated parts of the county.
The Council of Governments also has its voluntary integrated stormwater management program. The program encourages cities to participate in a program that promotes best practices for stormwater management.
Fourteen cities in the 16-county North Texas region have joined the program. By far, Tarrant County has the most representation with Fort Worth, Azle, Benbrook, Kennedale, Mansfield, Hurst, Southlake, Lakeside and Grand Prairie all taking part.
“When you look at the map of those who have implemented it, we’re not satisfied,” Marvin said. “We went out and did meetings with clusters of city managers and we got a lot of responses but we didn’t see a rise in applications coming in.”
In Arlington, 175 homes and businesses have flooded over the last month.
Along Canongate Drive near Gunn Junior High School, residents have seen the street flood four times over the last month and they’re blaming a new football field for messing up the drainage system in the area.
Maryhelen Bronson, who has lived on the corner of Canongate and California Lane since 2003, called the recent flash floods “horrifying and terrible.”
Water has reached her front door, bringing sand into her garage and flooding her pool.
“It looks more like the Trinity River,” she said, surveying the cloudy pool water she said has cost more than $1,000 to fix.
Her neighbor, Li Wang, said water rushed into her house and down the hall, flooding two bedrooms, an office and the dining room. Her garage door buckled from the force of the water.
Meanwhile down the street closer to the junior high, Iris Thornton said a sloped front yard created a berm that for years protected her home from water in the street. In September it wasn’t enough and water came into her garage.
“Someone’s going to have to do something about this,” she said. “They’re still going to ask us to pay taxes at the end of the year, you know.”
Arlington city officials didn’t respond to requests about flooding concerns around the school. Arlington spokeswoman Susan Schrock said the City Council is expected to receive a presentation on flooding issues at next week’s City Council meeting.
The area is not historically flood prone, and Bronson said she was shocked to see water nearly over-topping mailboxes in early September. She and neighbors point to the new football field, which is raised and drains into a retention pond. That water then flows out directly onto Canongate, where it pools before making its way to storm drains in front of Bronson’s home.
“As soon as I saw the water, I knew where it was coming from,” she said.
Leslie Birdow, an Arlington school district spokeswoman, said the district has taken steps to reduce the flow of water. The retention pond was made bigger and baffles were added to the spillway to slow the speed of water.
“We are making some changes at Gunn, but there are many areas that have flooded that never did before,” she said.
Rainfall raised suspicions about the impact of new development for other residents too.
Development near Randol Mill
Property owners along Fort Worth’s Randol Mill Road expect flooding from time to time when the Trinity River swells, but this year they’re seeing flash flooding along the roads.
Mark Singletary and others in the area blame two large housing developments — Trinity Oaks, a D.R. Horton project, and Oakridge by LGI Homes. Increased water in the area’s bar ditches is flowing from the development, he said. At Trinity Oaks, D.R. Horton cut down most of the trees, which would have helped soak up rainfall and LGI had not yet built retention ponds and other systems before September’s first heavy rains.
This week Singletary and other residents, backed by Fort Worth City Councilwoman Gyna Bivens, asked for a voluntary moratorium on building in the developments until a plan to mitigate flooding is reached, he said.
“They say the ground is oversaturated and that’s part of the problem, but it’s common knowledge asphalt, shingles and concrete driveways are a lot less permeable than saturated soil,” he said.
And officials should take into account the fact that flash floods are part of the Texas climate and likely aren’t going away whether you’re a believer in climate change or not.
“I will definitely say say when we talk to the water districts or other municipal organizations we definitely highlight what could potentially happen not just on the drought side but also how they need to address the runoff and flooding concerns,” said National Weather Service meteorologist Dan Huckaby. “As we become increasingly urbanized, there are more challenges. Concrete doesn’t soak up water very effectively.”