It is estimated that over 14-15 trillion gallons of rainwater fell over Houston and Southeast Texas, and more could fall before the end of the week.
Houston–the fourth largest city in the U.S.–has highways that now look like vast rivers. It’s hard to compare this storm to any other storm experienced. The devastating Hurricane Katrina saw 6.5 trillion gallons, and the two hurricanes are vastly different reports Vox: “Katrina brought destruction via storm surge and the crumbling of New Orleans levees. Harvey stalled over the coast after making landfall and dumped massive amounts of rain.” Though a number of other factors contributed to the unprecedented severity of Harvey.
Climate change
Rising sea levels in the Gulf, increased ocean temperature, and the summer heat and humidity in Texas all combined to make the storm worse. While massive amounts of rain fell on southeast Texas the flooding was particularly severe because of Huston’s topography and urban cityscape.
Huston’s topography
Houston and its surrounding suburbs are extremely flat. When rain water doesn’t have any low points to pool in the ground becomes inundated and unable to absorb water quickly enough so the flood water spreads out across the city according to the topography.
Urban Sprawl
Rapid urban expansion which has increased the square footage of paved surfaces. Under normal circumstances, rain gets absorbed by grasslands, parks or residential lawns–anywhere the soil is exposed. But when rain falls on concrete or asphalt, it cannot be absorbed into the ground and has nowhere else to go.
Ian Bogost of the Atlantic iterates, “The reason cities flood isn’t because the water comes in, not exactly. It’s because the pavement of civilization forces the water to get back out again.” In cities, up to 40 percent of the land is paved and impervious to water.
ProPublic documented this problem last year:
“As millions have flocked to the metropolitan area in recent decades, local officials have largely snubbed stricter building regulations, allowing developers to pave over crucial acres of prairie land that once absorbed huge amounts of rainwater. That has led to an excess of floodwater during storms that choke the city’s vast bayou network, drainage systems, and two huge federally owned reservoirs, endangering many nearby homes”
Infrastructure
As super storms hit with increasing frequency, it’s clear that city infrastructure is just not equipped to handle it.
In Houston, the freeways which people might use to evacuate the city are designed to capture run off water and divert it to holding locations. Bogost explains:
To account for the certainty of flooding, Houston has built drainage channels, sewers, outfalls, on- and off-road ditches, and detention ponds to hold or move water away from local areas. When they fill, the roadways 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 what makes evacuating a city like Houston so dangerous during a storm. In 2005, during hurricane Rita, Houston issued a mandatory evacuation for 2.5 million residents. People were stuck on the freeways for days and more than 100 people died while evacuating. Sending residents to sit in gridlock on freeways designed to become rivers during flooding would mean even greater disaster.
While it’s almost impossible to design for these unpredictable super storm scenarios, city planners now must look to design cities that can better withstand a storm’seffects andd support more effective evacuation routes and procedures.
Smart cities could offer solutions
“With new advancements in technology, cities have the opportunity to update their infrastructure, and improve their transportation and water supply systems,” says Chris Barker, a smart city and autonomous transportation expert. Smart city real time data can inform practices for maximizing the lifespan of buildings, road surfaces, bridge structures, and levees.
Increased green space and water management
Smart city infrastructure equips building rooftops with gardens that offers increased green space in the city and better water capture. Engineers in China are working on plans to combat urban flooding with “sponge cities”. Sponge city infrastructure consists of using water permeable materials and more green spaces to soak up rainfall and avoiding using concrete and asphalt wherever possible. Rivers, streams, and urban water diversion systems will also be interconnected so that water can flow away from flooded areas and not get socked up in a single waterway. Sponge cities also offer solutions to water shortages as well.
Traffic management
To improve traffic management for daily use as well as in planning evacuation routes, real-time traffic monitoring can be linked to vehicles and transit to commuter mobile devices enabling commuters to make dynamic route decisions based on roadway conditions and transit availability.
Safer evacuation routes
Smart city technology can use “3D modeling to help determine how to better evacuate people from urban corridors in the event of an emergency,” says Barker. “With improved vehicle-to-infrastructure communications, commuters are alerted to take the fastest, most convenient, or safest route”.
While the severity of super storms are largely unpredictable, they are proving to us again and again that our urban infrastructure and storm runoff systems are outdated and no longer equipped to deal with the quantity of rain released by storms like Harvey. The solutions offered by smart cities need to be implemented as we rebuild these deluged cities. The combination of climate change and rapid urban development make storms like these and their level of destruction an inevitable recurrence.
