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Don’t Blame Lack of Zoning Laws for Houston Floods

The rain in Houston has barely stopped and the flood waters have yet to fully recede, but already a narrative has been created in the media, led by ProPublica, but with a lot of people and publications playing follow the leader, that blame the severity of Harvey’s impact on the region squarely on the city’s lack of zoning codes.

Unfortunately, it’s nonsense.

First things first: Hurricane Harvey dumped a record amount of rain on Houston. According to the Los Angeles Times [1], the region received more rain in a few days than they normally get in a year. One of the meteorologists the Times interviewed said that it was over a trillion gallons of water and that the amount was unprecedented for the continental United States.

According to NOAA [2], only a handful of cities get more rain in a year than Harvey brought to Houston. No one could have planned for this devastation because no one ever anticipated it being a possibility. No storm drainage system in the country is built to handle that much rainfall in that little time.

As far as Houston’s lack of zoning goes, it’s a myth. Stephen Smith pointed out nine years ago [3] that Houston’s lack of normal land-use zoning has not prevented the city government from mandating minimum-parking requirements, setbacks, minimum lot sizes and all the other thousand ills that flesh is heir to. More than that, the main difference in the built environment of Houston and other cities that have experienced the bulk of their growth in the automobile era (one is tempted to write Anthropocene) is that infill development is much easier.

Houston, Dallas, San Antonio, Los Angeles, Phoenix, Jacksonville, and Tulsa all have downtowns with modern glass towers, acres of surface parking, subdivision after subdivision of single family detached residential on a hierarchy of streets feeding into a network of freeways.

Publications like ProPublica, Quartz, and Newsweek also have argued that zoning would have required developers to leave more of any given lot’s area as unpaved, preserving the wetlands and prairie that absorb water. But as Charles Marohn of Strong Towns [4] pointed out, the wetlands that were filled could have accommodated 0.02 to 0.1 percent of the rain Harvey brought.

Another fact that ProPublica’s narrative missed: Other cities, in addition to having zoning, have faced extreme flooding events from much less rain than Houston received this month. According to the Las Vegas Review Journal [5], for example, severe flash floods result from as little as two inches of rain in 25 minutes and enormous storm drains have been built under the city to cope. How big are they? Big enough that around 1,000 people live in them. Hurricane Sandy caused major flooding in New York and New Jersey with just seven inches of rain, according to NASA [6].  

Moreover, according to the Center for Neighborhood Technology [7], 92 percent of urban flooding takes place outside of designated floodplains, so restricting development within the floodplain is not effective. Flooding in cities around the country may not be as severe as that caused by Harvey, but urban flooding is still a national problem. Between 2007 and 2011, flooding in Cook County, Illinois, caused about $773 million in damage.

The relationship between impervious surface area and flooding seems to be very close, although the CNT found ambiguous evidence on this point. Only 10 of the 23 Cook County zip codes with the most flood insurance claims were also where the most impervious surface was. This is probably because they, like the people blaming building regulations for flooding, have got the short end of the stick: As two-thirds of the surface area in the typical American city is devoted to parking and roadway.

According to Charlie Gardner [8], around 20 percent of Downtown Houston is surface parking, while another 40 percent is devoted to streets—while in a typical city built before the 19th century, only about 15 percent of land would be devoted to roadway. This huge amount of urban land given over to asphalt dwarfs the amount of space available for housing and parks. Writing at Planetizen, Todd Litman [9] calculates that as much as 4,000 square feet of land per automobile is given over to roadway and parking—that’s a lot of land consuming taxes instead of producing them. For comparison, according to Michael Lewyn [10], until 1998 the minimum lot size in Houston for a new home was 5,000 square feet. This is important because standard planning practices are based around retaining storm water on site, meaning that buildings need large green space foot prints to absorb water, but if the effect of such regulation is to separate buildings, then they could lead to more driving and hence more asphalt.  

Even then, geography matters: According to economist Phil Magness [11], some of the worst flooding, in terms of water volume, occurred in the rural areas along the Brazos River.

What lessons can we learn from Harvey? Geography and geology are important to how cities handle severe storms and sea level rise. More importantly, cities do not need historic storms to suffer from flooding and the 60 percent of a city’s surface area devoted to parking and roadway likely exacerbate flooding more than residential or commercial development. Compact, walkable cities of the types advocated by New Urbanists should be better able to deal with urban flooding.

Matthew M. Robare is a freelance journalist based in Boston.

This article was supported by a grant from the Richard H. Driehaus Foundation.

18 Comments (Open | Close)

18 Comments To "Don’t Blame Lack of Zoning Laws for Houston Floods"

#1 Comment By Conewago On September 1, 2017 @ 5:47 pm

There is a reason that Russell Kirk called the automobile the “mechanical Jacobin.”

But most “conservatives” alive today in America are so acculturated to worship the car and car culture that they will surely lambast this article.

#2 Comment By Don N On September 2, 2017 @ 2:15 am

I agree with every single point in your article. Harvey was going to be a catastrophic flood whether it dropped it’s rains on 2017 Houston, 1996 Houston, or 1960 Houston. Still, that doesn’t mean that greater Houston hasn’t done a poor job of planning it’s drainage infrastructure to deal with the non- biblical flooding events that regularly plague the region. No appropriately planned city should have 3 five hundred year flood events in 4 years.

#3 Comment By polistra On September 2, 2017 @ 5:09 pm

No. Building in flood zones is responsible for flooded buildings. This is EXTREMELY SIMPLE, and well-disciplined cities have learned how to do it right. Houston was not well-disciplined, and Libertarians have been praising its idiocy for decades.

#4 Comment By Joe Beavers On September 3, 2017 @ 12:15 pm

Don’t forget elevation. Houston is about 50 feet above sea level, Beaumont (about 80 miles away) has an elevation of about 16 feet, Texas City (about 40 miles away) is 10 feet.

I lived just west of Beaumont when we had the last 500 year flood in Houston (2002) and we were hit with a wall of water as Beaumont is sort of the drainage ditch for Houston.

At less than a foot per mile of decline, and with clayish soil, the place would flood whether Houston was there or not.

#5 Comment By connecticut farmer On September 3, 2017 @ 1:00 pm

The most important point that has to be shoved back into the faces of the critics is the sheer volume of rainwater dumped on Houston and surrounding environs within a relatively short time span. A TRILLION gallons of water. The mind reels at the number. This is the single most important factor, notwithstanding the significance of the other issues which the author raises–and with which I agree.

Imagine if a storm of this size struck the SE and Mid-Atlantic seaboard? Uh-oh! Here comes Irma!

#6 Comment By Jon S On September 3, 2017 @ 3:06 pm

The conservative solution is to get rid of publicly provided flood insurance. Coupled with non-recourse mortgages. If bankers were on the hook, there would be no development in flood-prone areas.

#7 Comment By DrivingBy On September 3, 2017 @ 3:18 pm

Huh? Houson is flat and the land is clay. Even with half of their current pavement, half of Harvey would have flooded it.
Civilization has always congregated near water. Now, we build permanent structures on what we know are flood-prone lands; people have collectively decided that the desirability of such locations outweighs whatever happens “later”.
Perhaps we need to cut back on Federally subsidized flood insurance, so that people weigh the risk part of these events as well as the benefit.

But no matter what measures were in place, Harvey was going to flood Houston. There is likely no build-able city-sized land area which can shrug off four feet of rain in two days!

#8 Comment By Ken T On September 3, 2017 @ 5:56 pm

The experts have been predicting for at least a decade that Houston’s development pattern would lead to a disaster the next time the area was hit with a major hurricane. The fact that the disaster that actually occurred turned out to be even worse than predicted does not change the fact that it was predicted. And arguing about whether it was lack of zoning or lack of environmental protections or too much parking or something else is nothing more than a way to avoid facing the fact that this was predicted and no one in authority paid any attention.

#9 Comment By mrscracker On September 3, 2017 @ 6:11 pm

We experienced similar flooding last year when 2 feet of rain fell in 48 hours and an additional 8 inches the 3rd day.
There were similar unkind comments online about “karma” for Trump voters,but what area can escape flooding with that kind of downfall?
As someone else pointed out,soil types are key. Heavy clay holds water for a long time. We had neighborhoods that were flooded for weeks and weeks.

#10 Comment By james sullivan On September 3, 2017 @ 7:21 pm

The flooding from Sandy was not from rain but from ocean tidal surge. It’s misleading to say that NY and NJ flooding came from only 7 inches of rain.

#11 Comment By muggles On September 4, 2017 @ 5:53 pm

As elsewhere (above) was noted, Houston’s clay soil does not “absorb” water. A small amount, but very little. Until about 10 years ago the local brick making industry just dug it up, fired it and turned it into bricks. Do bricks absorb water?
Silliness and evil to blame Houston’s politics for 3-4 feet of water in three days. It is totally flat and bayous are shallow, muddy and easily silt up. It is true developers will rethink plans in rebuilding, but what major city wouldn’t badly flood in an 800 year flood event? Zero.

#12 Comment By cdugga On September 4, 2017 @ 11:09 pm

Covering land with concrete increases the severity and likelihood of flooding. That is disputed by who? Okay, if it is not disputed by anybody, who is it that panders to developers who go around destroying green space and wetlands? Like, are we saying that republicans are stupid or are we saying republicans are complicit? I would say two wrongs make the right, or the GOP. There may be a middle ground, but it is passed further on the right every election cycle.
Of course no amount of planning will completely abrogate the chances of catastrophic flood events like the giant white rabbit that everyone saw. It is unfortunate that mainstream GOP reactive policy is to put everything to a black or white, with us or against us, enableing development or standing against it litmus test. The new creative destruction is a publicly funded jobs program to address unregulated private development whereby costs are placed on the taxpayer and profits garnered by GOP corporate sponsors. You know, the same old public private partnerships, where profit goes to the private individuals that gotsda power, and overhead and all costs are passed on to the taxpayer. Sounds like a GOP healthcare plan doesn’t it?
In texas I have seen billions spent by the taxpayer to try and ameliorate the problems caused by unplanned development and have come to the conclusion that, at least in texas, it is a jobs program vested in continued destruction to continue new construction. Turn thousands of acres into warehousing and the now obsolete shopping complexes, spend billions on roadways and turning all the local streams into giant concrete drainage ditches, and repeat the process with the idea that more lanes of highways and byways mean less congestion when it means exactly the opposite as traffic slows every time somebody in the left needs to move all the way to the right, or somebody in the right needs to move all the way to the left. I have watched millions spent trying to shore up the banks of huge drainage ditches eating away at the houses originally built along meandering tree covered streams, every time there is a texas thunderstorm. The idiocy is profound. Unless you are the developers and companies making money trying to fix the destruction. Then it all makes sense. The conservative solution mentioned by Jon S above is at least part of a progressive plan forward. But we would still have to publicly protect those who are downstream of development caused flooding if we were to be fair and truthful. Otherwise we can just stick it to them and use the standard republican strategy of, it is not a problem until it actually happens, and then when it actually happens, good luck trying to prove the cause was something other than the will of god, god willing.

#13 Comment By mrscracker On September 5, 2017 @ 5:04 pm

muggles says:

“As elsewhere (above) was noted, Houston’s clay soil does not “absorb” water. A small amount, but very little. Until about 10 years ago the local brick making industry just dug it up, fired it and turned it into bricks. Do bricks absorb water?”
**************
Bricks absorb water only slightly less than “black gumbo” clay soil does.
That’s still not an excuse for trashing wetlands or poor planning. But permeable pavement over clay doesn’t work so well. You’d still have a problem with standing water after heavy rainfall. Crawfish production in SW La. & SE Texas works because that type of soil retains the water in the ponds.

#14 Comment By John_M On September 5, 2017 @ 7:24 pm

With rain like that, almost anyplace would flood. The floodplain boundaries need to be updated but you need to plan for floods so that you reduce the damage. Not far from where I live, the houses are on stilts so that the house is not damaged by the occasional flood. The houses will still be damaged by the rare great flood, but the vast majority of the floods just restrict access by boat, with vehicles moved to higher adjacent land. When I lived in the East, I saw such development in the Delaware valley with quite high stilts to deal with the river flooding from hurricanes and tropical storms. Stilts / pilings are not that expensive. And concrete / cinder-block with access and drainage holes works too.

In areas likely to be hit by both floods and winds, the cost is somewhat higher and you need shear walls or diagonal bracing to handle the loads. But the space below is not finished and can be used for other purposes the rest of the time.

#15 Comment By c matt On September 6, 2017 @ 6:43 pm

There were similar unkind comments online about “karma” for Trump voters,but what area can escape flooding with that kind of downfall?

That’s rich, considering Harris County (in which Houston is located) went for Hillary, and the last three mayors were democrats! Hey, maybe it was karma.

#16 Comment By Balzerdash On September 6, 2017 @ 9:05 pm

This comment zeros in.

“Jon S says: September 3, 2017 at 3:06 pm
The conservative solution is to get rid of publicly provided flood insurance. Coupled with non-recourse mortgages. If bankers were on the hook, there would be no development in flood-prone areas.”

If government did not massively subside this, it would not happen on this scale. The informed buyer, would not debt-buy homes with this risk, if informed, and not subsidized.

#17 Comment By Juliana Bright On September 18, 2017 @ 2:30 am

It’s funny you should mention Tulsa in connection ion with flooding, because the city has made flood prevention a major civic priority since the 1984 Memorial Day flood (which was, of course, preceded by a decade+ of organization and advocacy by citizens in flood-prone areas). Before then, Tulsa had some of the worst flooding problems in the nation. Nowadays Tulsa has the lowest national flood insurance premiums.

Tulsa’s storm water management system (infrastructure, programs, and regulation) is designed to handle the 100-year flood, so the city would also be devastated by a 500-year flood like Harvey. But floods were never even on my radar, growing up there. For that matter, thunderstorms never closed any streets, or even made me wade through puddles on my way to the schools bus stop. If you ware interested in how a conservative city might deal with flooding, Tulsa makes a good case study.

#18 Comment By Mayme On September 21, 2017 @ 10:21 am

No one could have planned for this devastation because no one ever anticipated it being a possibility.

Excuse me! Since 1950 this has been being predicted by NASA….. [12]