Hurricane Harvey rocked the Gulf Coast, but Troy Kimmel, a meteorologist and University of Texas at Austin severe weather professor, said although it is 165 miles inland from Houston, Austin was “lucky” to come out unscathed.

Areas only 20 miles east of the capital city received 15-20 inches of rainfall—an amount that has had devastating results for Central Texas in the past, Kimmel said.

Austin’s rainfall may not have been the 50 inches of rain and “biblical flooding” experienced by Houston, but Austin has had its share of flooding disasters and due to its geography, remains particularly vulnerable to the destructive forces of Mother Nature. Kimmel said a storm like Harvey could hit Austin in the future.

October marks the two-year anniversary of the 2015 Halloween flood that placed some of South Austin underwater. It was the third of what would become four presidential disaster declarations in four years for Travis County between 2013 and 2016: the 2013 and 2015 Halloween floods, and the 2015 and 2016 Memorial Day floods.

As it continues its unprecedented rate of growth, the city is forced to strengthen its mitigation efforts in order to protect its citizens and most vulnerable areas.

‘Flash Flood Alley’

As North Austin resident Dorsey Twidwell remembers it, 2 1/2 years ago during the Memorial Day flood of 2015, he walked out the back door  of his home and—standing on his porch—he felt as though he was sailing on a ship, he said.

“There was water everywhere,” Twidwell said.

He recalls the water rising at a rapid rate. The level in his backyard, which sits parallel to Walnut Creek on Cedarbrook Court, peaked at about waist-deep and carried a dangerously forceful current downstream.

According to data from the Flood Safety Education Project, the geography of Texas makes it vulnerable to some of the heaviest rainstorms in the world. Travis County sits in an area of Central Texas nicknamed “Flash Flood Alley”—one of the most flash flood-prone areas in North America, according to Austin’s Office of Homeland Security and Emergency Management.

According to the National Oceanic and Atmospheric Administration, flash floods occur when heavy rainfall forces creek and river beds to overflow. Experts at NOAA consider flash floods the most dangerous flood variety because they combine the power of a flood with “incredible speed” and can occur with no warning.

Although Twidwell and his wife, Bunnie, survived with little to no structural damage to their home, structures throughout downtown Austin were left submerged under several feet of water.

For Mark Feist, a resident of the Aldridge Place neighborhood in Central Austin, one of those structures was his backyard garage apartment, which he said took in 2-3 feet of water. He said the floodwaters were powerful enough to wash cars down his street.

“It’s true flash flooding; it comes with fast-flowing, dangerous water,” Feist said. “It doesn’t stick around. You can have all this water come and go within 30 minutes.”

Feist said his property, which sits atop the underground tunnel that Waller Creek runs through, floods regularly.

Flash floods prompted by heavy rainfall were the major contributors in the four disaster declarations that resulted in loss of life and over $100 million dollars in damage in Austin.

‘A very disheartening situation’

Matt Hollon, manager of the Austin Watershed Protection Department’s Planning Division, said though the city is naturally prone to flash floods, early planning mistakes exacerbated the vulnerability in some areas of the city.

When Austin first received its flood plain maps from the Federal Emergency Management Agency in the late 1970s, Hollon said the technology used to develop the maps was in its early stages, and poor planning decisions were made.

“[The flood plain maps] weren’t delineated properly, and development occurred in unsuitable areas,” he said. “It was a very disheartening situation.”

This led to the development of thousands of properties within the 100-year flood plain, which is an area that FEMA calculates has a 1 percent chance of flooding per year—or a 26 percent chance of flooding over the lifetime of a 30-year mortgage.

According to the 2016 Watershed Protection Master Plan 1,981 structures lie within the Barton, Bull, East and West Bouldin, Little Walnut, Shoal, Waller and Walnut creeks watersheds’ 100-year flood plains, 773 of which the city estimates would be inundated in a 100-year storm.

Development within the flood plains has plateaued since the city’s flood plain ordinance went into effect in 1983, Hollon said.

“We’re basically seeing no new construction going down in these hazard areas, and you’re seeing all these sins of the past corrected,” he said.

Among the most dangerous aspects of flash floods are low-water crossings, areas where floodwaters commonly breach the roadway. According to Hollon, 75 percent of Austin’s water fatalities were due to low-water crossings. The master plan counts 1,866 low-water crossings in Austin, 189 of which fall within the aforementioned watersheds.

Efficiency of the city’s drainage infrastructure, namely storm drainpipes, also plays an important role in an area’s vulnerability to flooding. Poor infrastructure can turn a smaller storm into a 100-year flooding event. Of the 1,100 miles of drainage pipes running through Austin, roughly a quarter were built before modern regulations were put into effect. Nearly all the old, undersized piping lies within the urban core neighborhoods where development is most prolific,
Hollon said.

He said much of the old piping cannot handle more capacity. However, replacing old infrastructure is an expensive undertaking—city staff estimates a price tag close to $1 billion.

District 7 Council Member Leslie Pool sees stormwater and drainage infrastructure as a paramount issue as the city continues to grow.

“We were a sleepy little town,” Pool said. “The last 20 years have been this incredible expansion, and it’s expensive to keep up with. We just have to keep working at it day by day and not make things worse.”

‘Flood amnesia’

Following his Memorial Day 2015 experience, Twidwell began going to community meetings, communicating his experience and asking questions. However, he found that the community’s momentum around the issue faded as time passed.

“People around here suffer from flood amnesia,” Twidwell said. “It’s like my uncle used to say, ‘The roof only leaks when it rains.’”

Pool said the flood amnesia leaks into policy as well, which can make it difficult to continually prioritize the issue.

“People forget; policies erode; and the significant concerns that people have get dulled over time if the circumstances don’t repeat themselves or if it doesn’t happen to you,” Pool said. “If you have not been affected by flooding you don’t have the level of awareness and sensitivity to how destructive and dangerous flooding is.”

Putting Protections in Place

Twidwell said flood amnesia has not affected him; it has become what he calls “flood passion.” He has been working on the city’s Bond Election Advisory Task Force, placing an emphasis on funding stormwater and drainage infrastructure.

Previously he served as one of the 22 appointees to the Flood Mitigation Task Force, which in 2016 provided 11 recommendations to City Council on how to better prepare the city for the inevitable.

“It’s all about constant vigilance,” Twidwell said.

One of those recommendations, according to Hollon, is being proposed by the watershed protection department through CodeNEXT—the ongoing overhaul of the city’s land development code—for redevelopment regulations for large multifamily and commercial projects.

Currently the threshold for a new project is it must not contribute more stormwater runoff to the drainage system. Hollon said the new regulations would require those larger projects to provide substantial improvement and go “above and beyond” current regulations.

“We’ve had this no-harm rule for a long time,” Hollon said. “Folks have not been piling on and adding to the problems, but they haven’t really started to chip away and reverse the trend and try to improve it.”

The rules around flood plain development have also tightened significantly since the 1980s, but the city is still working to rid itself of the unregulated development of the past. Hollon said since 2012 the number of structures within the 100-year flood plain expected to flood has dropped nearly 25 percent, from 2,380 structures to 1,816.

The city has become more vigilant in its public awareness campaigns regarding flash flood warnings and low-water crossing closures. Hollon said the “Save yourself! Turn around—don’t drown” campaign has had success in educating people about the dangers of low-water crossings.

But when it comes to the forces of Mother Nature, Pool said there is “very little” society can do. Hollon agrees.

“We’re really just trying to make sure we’re prepared, and if a Harvey hits, we would do as well as we can,” he said. “It’s going to take years because all of these projects are expensive. But we’ve got to start.”