Houston Fears Warming Will Cause Catastrophic Flooding
By Tom Dart, The Guardian
Sam Brody is not a real estate agent, but when his friends want to move home they get in touch to ask for advice. He is a flood impact expert in Houston — and he has plenty of work to keep him busy.
The Texas metropolis has more casualties and property loss from floods than any other locality in the U.S., according to data stretching back to 1960 that Brody researched with colleagues. And, he said, “Where the built environment is a main force exacerbating the impacts of urban flooding, Houston is number one and it’s not even close.”
A road floods in Houston, Texas after rains from Hurricane Ike in 2008.
Near the Gulf Coast, Houston is also at annual risk from hurricanes: it is now into the start of the 2017 season, which runs from this month to November. Ike, the last hurricane to hit the Houston region, caused $34 billion in damage and killed 112 people across several states in September 2008.
There is little hope the situation is going to get better any time soon. Earlier this month, days after Donald Donald Trump announced the U.S. will withdraw from the Paris accord on climate change, a new report warned that rare U.S. floods will become the norm if emissions are not cut.
Brody, a professor in the department of marine sciences at Texas A&M University’s Galveston campus said the requests for help in Houston from people moving homes inspired him to create a forthcoming web tool so that people can type in an address and get a risk score.
“If you can see your crime statistics, shouldn’t you be able to see your flood risk also? And other risks as well, human-induced risks?” he said. The site will be named Buyers Be-Where.
In May 2015, eight people, many of them motorists, died in Harris County when a storm dropped 11 in of rain in parts of the city in 10 hours.
Last year, another six lost their lives in an April storm that hurled 240 billion gallons of water at the Houston area. An inch of rain fell over the county in only five minutes, with a peak of 16.7 in in 12 hours.
The events damaged thousands of homes, turning major freeways into canals and piling up vehicles as if they were in a junkyard. The 2016 flood cost an estimated $2.7 billion in losses and prompted more than 1,800 high water rescues.
Significant rains have always been a feature of life in south-east Texas. What bothers Brody and local environmentalists is the extent to which human activity is making things worse.
Flooding at a gas station in Houston, Texas.
Credit: Todd Dwyer/flickr
“Houston is situated in a low-lying coastal area with poorly draining soils and is subject to heavy rainfall events and storm surge events, which makes it very prone to flooding. And the climate is changing. In Galveston Bay the sea level is rising. We know the area is experiencing more heavy downpours,” Brody said.
“It pales in comparison with the other driving force, which is the built environment. If you’re going to put 4 million people in this flood-vulnerable area in a way which involves ubiquitous application of impervious surfaces, you’re going to get flooding.”
In other words: there is a lot of concrete in Houston. In 2000, 4.7 million people lived in the Houston metropolitan area. Now the population is about 6.5 million. While efforts are under way to densify and improve public transport in the urban core, much of the growth has been suburban, where houses are big and cheap and commuters drive long distances on some of the world’s widest freeways. The city keeps loosening its belt: a third ring-road cuts through exurbs some 30 miles from downtown, spurring more expansion.
To the west, idyllically named middle-class subdivisions sprout on former farmland, served by new retail complexes and multi-lane roads. Here, 3,500 square foot homes can be bought for less than $400,000, helping to explain the region’s population explosion. But it may be coming at a price — one paid downstream.
The Bayou City’s vein-like network of creeks and rivers are one of its defining features, but heavy rains turn them from subdued to seething. The Buffalo Bayou’s light brown waters meander 50 miles from west of the city through downtown to large bays in the east. The threat of catastrophic overflowing is mitigated by two dams built in the 1940s that the Army Corps of Engineers has classified as having an “extremely high risk” of failing and is now repairing.
The danger is lessened, too, by the natural defence of the western plains — but here, water-retaining grasses are being replaced by non-absorbent surfaces, which encourage water to travel downstream. Brody calculates that each new square metre of pavement in Houston on average adds $4,000 worth of flood damage.
Founded in 1992, the Katy Prairie Conservancy, a not-for-profit land trust, has a field office in bucolic land an hour’s drive from the skyscraping oil industry headquarters dotting central Houston. The Katy Prairie was once estimated at 500,000 to 750,000 acres, before Houston boomed. The Conservancy owns about 14,000 acres — an area roughly the size of Manhattan. It helps protect another 6,000, quietly working to shield fields from sprawl in a city and state better known for damaging the environment through oil and gas production than for preserving its natural resources.
“We may not be able to stop flooding but we ought to be able to better manage it,” said Mary Anne Piacentini, the executive director. “Our grasses are great water-holding reservoirs. Initial studies that we were doing with the Harris County Flood Control District show that our prairie grasses can hold up to about 8 in of water.”
Her colleague, Wesley Newman, likens tall grass prairies to an upside-down rainforest: the grass can grow to 6ft to 8ft above ground and two or three times as much below. “We’ve come to realise that the grassland, the tall grass prairie, is maybe even more important than the wetlands,” Piacentini said. “The more that we can restore, the more likely it is that we will be able to increase the water-holding capacity of what we do, and that affects directly downstream Houston.”
Inside Houston’s second ring road, 30 miles east, a photo album sat on a table in Dean Bixler’s living room. It was not filled with happy family portraits, but murky images of the flood-ravaged rooms of his house, with sofas elevated on chairs above coffee-coloured water.
The 60-year-old bought it in 1996, not imagining that his renovation budget would ever need to take the cost of pumps into account. Bixler said his house, built in 1960, has flooded three times since 2009, submerging his long front lawn and invading his home. “You could not see any grass. That’s a lot of frickin’ water,” Bixler said. In 2015, the repairs took about five months. In 2016, his flood-proofing measures kept water infiltration to an inch and a half.
Flooding closes a road in Texas.
Bixler is a member of Residents Against Flooding, a group that last year filed a lawsuit against the city and a local infrastructure authority alleging that poorly mitigated developments are causing hundreds of homes to flood.
“The truth is that most of the flooding in Houston is manmade,” said Ed Browne, another member, pointing out that many people who get flooded, Bixler included, are not in the 100-year floodplain — an area calculated to have a 1 percent annual chance of flooding.
But Bixler’s part of town has in the past decade been extensively redeveloped, with new shopping malls, office blocks, homes and apartment complexes, many designed, critics say, with flood-control strategies such as elevation that appear to prioritise self-protection with little overall plan as to what happens to the diverted water.
It is a worrying vision of the future: stronger and more frequent storms with fewer natural barriers, while rapid and haphazard urban development with limited oversight creates new at-risk zones or worsens drainage in known problem areas.
The Harris County flood control district did not respond to requests for comment; its executive director, Russ Poppe, told the Houston Press last year that there are regulations to stop builders from increasing flood risks and that it is difficult to protect against exceptionally violent storms.
While residents battle for local improvements, there are predictions worthy of a disaster movie for what could happen if a powerful hurricane barrels directly into Houston’s industrial east. “If we get 20ft plus of water up the Houston Ship Channel it will be apocalyptic. I think all of us that have studied hurricanes are absolutely petrified about a big storm flooding the Houston Ship Channel and basically causing a number of those storage tanks to become unmoored and releasing their contents,” said Jim Blackburn, an environmental attorney and co-director of the Severe Storm Prediction, Education, and Evacuation from Disasters (SSPEED) Center at Rice University.
“There’s a lot of very dangerous materials that are generally handled, all things considered, fairly well, but they’re not designed against 20ft floods and if we have that it’s just going to be an incredibly bleak situation,” he said.
The coastal area from Galveston to Houston is home to several hundred thousand people, Nasa’s Johnson Space Center, the U.S.’s second-biggest seaport in terms of total tonnage, some of the nation’s largest refineries and its biggest petrochemical complex.
It is not lost on environmental activists that those refineries, as part of the fossil fuels industry, may be imperiled by extreme weather linked to climate change.
As a ProPublica/Texas Tribune investigation pointed out last year, had Ike been a little stronger and not changed course at the last minute in 2008, Blackburn’s nightmare scenario might have become reality.
According to the SSPEED Center, a 24 ft storm surge along the Ship Channel would cause about 90 million gallons of crude oil and chemical substances to rush into neighbourhoods and Galveston Bay — an event that a 2015 report claims “could easily become the worst environmental disaster in U.S. history”.
To say nothing of the economic impact on the region and the nation — a lengthy shutdown of south-east Texas’s facilities would be felt all over the country as products such as gasoline and jet fuel would become scarcer and more expensive.
A multibillion-dollar coastal barrier has long been on the wish list — but is far from being realized, since there is as of yet no consensus over the design, implementation and funding. “If you look historically at major hurricane enters Galveston Bay every 15-20 years, so it’s going to happen,” said Brody, the professor.
“It is something that keeps me awake at night every June that rolls around, hurricane season, because it’s not if, it’s just when — and every year we put more people and critical assets in harm’s way. We keep rolling the dice and the stakes become higher.”
Reprinted with permission from The Guardian.
Source:: Climate Central