After Harvey dumped more than 9 trillion gallons of water onto Houston in two days, it is an understatement to say the city has faced stormwater challenges this year. But even when a historic storm is not ravaging the city, Houston faces stormwater challenges.
"Houston is not designed to handle this kind of rainfall," Professor Sam Brody, an expert on urban and floodplain management at Texas A&M University, told CNN.
City planning and water experts are analyzing Houston’s particular stormwater challenges in the wake of Harvey. Experts told CNN that urban sprawl, weak regulations, and poor reservoir and land management increased the damage Houston will face after the storm.
“Houston poses both a typical and an unusual situation for stormwater management. The city is enormous, stretching out over 600 square miles. It’s an epitome of the urban sprawl characterized by American exurbanism, where available land made development easy at the edges. Unlike New Orleans, Houston is well above sea level, so flooding risk from storm surge inundation is low. Instead, it’s rainfall that poses the biggest threat,” The Atlantic reported.
Bayous, which are slow-moving rivers, provide large-scale drainage to the area. Drainage channels, sewers, outfalls, on-and off-road ditches, and detention ponds also play a critical role.
As Thomas Debo, an emeritus professor of city planning at Georgia Tech and author of a popular textbook on stormwater management, told The Atlantic: “There is no silver bullet for stormwater management.”
Roadways, meanwhile, provide overrun. “The dramatic images from Houston that show wide, interstate freeways transformed into rivers look like the cause of the disaster, but they are also its solution, if not an ideal one. This is also why evacuating Houston, a metropolitan area of 6.5 million people, would have been a terrible idea,” the report said.
Other factors challenging stormwater management in Houston include the city’s “almost dead-level topography, constrained stormwater-management capabilities and adverse soil conditions,” The Washington Post reported.
The Post explained:
Houston’s stormwater system simply cannot handle the volume of rainwater dumped on the city by Harvey. Making matters worse, the amount of surface water that Houston’s open, vegetated land can absorb is limited. The high clay content of soils impedes absorption. And close to bayous, bays, rivers and the Gulf of Mexico, the underground water table is not far below grade, which is why most homes in Houston are built without basements. Consequently, many Houston neighborhoods have limited capacity for retaining and evacuating rainwater. Runoff collected in drainage swales or fed into underground pipes ultimately has nowhere to go except into slowly draining creeks and bayous. A heavy, persistent rainstorm can rapidly fill natural waterways and storm systems to overflowing, with rainwater backing up onto neighborhood streets and properties.
Stormwater management rarely grabs public interest — except when hurricanes and major storms occur.
“One problem is that people care about flooding, because it’s dramatic and catastrophic. They don’t care about stormwater management, which is where the real issue lies. Even if it takes weeks or months, after Harvey subsides, public interest will decay too. Debo notes that traffic policy is an easier urban planning problem for ordinary folk, because it happens every day,” The Atlantic reported.
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Image caption: Texas National Guard soldiers conduct rescue operations in flooded areas around Houston, Texas 27 August, 2017. (Photo by 1Lt. Zachary West, 100th MPAD)
Image credit: "Texas National Guard," The National Guard © 2017, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/