Most cities inundated with up to 121 centimetres of rain would face severe flooding, but experts are saying that Houston is facing a particularly dire situation after Harvey.
About 30,000 residents in the Texas city were forced to flee as the massive hurricane swept through the region. The storm left behind thousands of flooded homes and streets. On Wednesday, officials confirmed that 20 people had died as a result of the natural disaster.
READ MORE: 20 Harvey-related deaths confirmed in Texas as storm moves on to Louisiana
University of Toronto civil engineering professor Jennifer Drake says the “unprecedented” amount of rainfall experienced by the United State’s fourth-largest city is largely to blame for flooding.
“This isn’t a normal situation,” Drake said.
Houston has a concrete problem
But Houston’s lagging infrastructure hasn’t helped the problem.
“The way the city’s grown and developed has amplified the situation,” Drake said, explaining that it’s largely concrete with a lack of natural infrastructure, such as wetlands.
According to The Associated Press, the city’s drainage grid, which was designed in the Depression-era, is another culprit.
The entire system is designed to clear out only 12 to 13 inches of rain per 24-hour period, Jim Blackburn, an environmental law professor at Rice University told The Associated Press.
“That’s so obsolete it’s just unbelievable.”
READ MORE: What Hurricane Harvey-level floods would look like in a Canadian city
Lack of regulations
Drake also notes that Texas doesn’t have a statewide flood control policy, which means there’s a lack of framework for cities to work together and co-ordinate efforts. The problem isn’t unique to the southern state.
“Many parts of North America don’t have integrated, holistic management,” Drake said.
One key aspect of a proper conservation policy would prohibit cities from developing flood-prone areas. Much of Houston’s developed areas are in flood plains because of lax regulations, a 2016 ProPublica article noted.
Do Canadian cities have the same problem?
The situation in Canada is better — at least in some parts of the country. In Ontario, for example, Drake says there’s a unified provincial regulatory body that works to manage floods.
The province maps out flood plains that can’t be developed, it works with cities to monitor at-risk areas and buildings.
READ MORE: What Hurricane Harvey-level floods would look like in a Canadian city
However, some areas in Canada don’t have similar organizations. Drake notes Calgary’s downtown core is largely built on a flood-vulnerable area.
How can cities better prepare for flooding?
Nick Reid, the executive director of Ryerson University’s Urban Water Centre, works to help metropolis areas better integrate natural infrastructure into big cities.
Cities need to move toward “low-impact development,” which means using Mother Nature to slow water down, he explains.
WATCH: Dramatic time-lapse footage shows just how quickly the floodwaters in Houston rose
“It’s about working with nature rather than against it.”
While overhauling a city’s infrastructure can be costly and take years, they can take smaller steps to improve the situation. Reid cites roof-top green spaces as one example.
At Ryerson University in Toronto, Reid says the engineering building’s roof has been converted into a farm, which means rainwater will be absorbed rather than lead to floods. The farm also produces 10,000 pounds of food.
— With files from The Associated Press