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Building resilient cities

September 7, 2017

In the wake of Harvey and Irma, ASU's Charles Redman talks about how to make cities more able to weather calamities

The flooding in Houston was exacerbated by how the city was built. Like many cities, Houston basically paved over the existing landscape, a grassy plain that evolved to handle large rainfalls by acting like a sponge.

New ideas on how to build more resilient cities focus on working with nature, rather than trying to master it, says Arizona State University Professor Charles Redman, the founding director of ASU’s School of Sustainability and a distinguished scientist in ASU’s Julie Ann Wrigley Global Institute of Sustainability.

What this means, Redman says, is building infrastructure systems that are safe-to-fail, rather than fail-safe, and recognizing that the city should be able to take advantage of natural features of the land rather than to solidify it with concrete.

Redman leads a group of researchers from 15 institutions in a National Science Foundation-sponsored project called the Urban Resilience to Extreme Weather Related Events Sustainability Research Network (UREx SRN), which focuses on ways to make cities more resilient to natural calamities.

Here, he talks about how cities can be better prepared to withstand natural calamities.

Question: What can cities do to be better prepared for events like Harvey and Irma?

Answer: There are two areas of improvement, the first being altering the nature of the “hard” infrastructure, and second to enrich and make more effective the “soft” infrastructure of organization, cooperation, information flow, etc.

The overarching problem with cities like Houston is that they have built over the natural landscape with impervious surfaces, and with impediments to the natural flow of surface runoff. A more effective approach may be to implement infrastructure systems that work with the land to facilitate runoff rather than try to control it, but acknowledge and plan that if a specific threshold is exceeded and the system “fails” in some sense there are backup plans in place that minimize the adverse impacts.

Q: How does a safe-to-fail system operate vs. a fail-safe system?

A: This is about managing risk in an increasingly uncertain world. The fail-safe system assumes you know what is coming and that it can be handled if we build a big enough dam, levee, pipe, sea wall, etc., for protection. The problem is that many extreme events such as Katrina, Fukushima, Sandy and now Harvey go beyond the expected and result in disaster. A fail-safe approach seeks to totally prevent harm related to the weather event; however, if the event does exceed the design of the infrastructure there is little back up protection and disaster ensues.

In each case, much of the disaster might have been avoided or at least minimized through more effective awareness of the threats, better planning and well-thought-out responses. This is at the heart of the safe-to-fail approach that accepts the possibility that the hard infrastructure might be insufficient and has multiple back-up plans to ameliorate the impact. Using green infrastructure with secondary benefits, relying on multiple approaches, and moving people out of harm’s way are among the approaches to minimize negative impacts.

Q: What are some of the “soft” infrastructure approaches to becoming more resilient?

A: Short of changing the physical structure of the city, “safe-to-fail” strategies would focus on how the city prepares and responds to weather-related extreme events. The first is to map the relative vulnerability of people in different locations of the city, and as the event approaches the rescue teams don’t have to wait for 911 calls but can focus on the most likely areas to flood before the disaster develops. 

The second is to develop a system of refuge centers that are appropriate to the scale of the potential dislocation and pre-plan strategies for getting people there. In Houston planned shelters were a fraction of the size needed. A separate issue is that two of the Houston’s reservoirs threatened to overtop their embankments. It is a common mismanagement problem that reservoirs are kept too full in order to maximize available water when they should be kept lower during hurricane season.

Q: What are some of the tools being developed in the UREx SRN program?

A: We are focusing on a variety of tools, and more, to build a method of bringing together the diverse elements of city government with relevant citizen groups to plan for future hard and soft infrastructure. Primary among the tools are a variety of green infrastructure constructions that take advantage of natural ecosystem services to ameliorate the impact of extreme weather events and then, in between events, to provide desired amenities like greenbelts and recreation fields. We are also constructing maps of populations most vulnerable to various types of extreme events and systems to minimize the impact on these populations.

Q: How does the program make cities more resilient?

A: We believe there are basic steps in gathering information, planning for the scale and intensity of events that were not common in the past, but are expected more today and in the future. We want to create planning templates that will ensure that cities are more “resilient-ready” to floods, heatwaves, droughts and other weather-related extreme events.

Another category of action that will enhance the capacity of a city to handle extreme events is to build the cooperative attitude of helping each other and working together to face the challenge rather than relying totally on outside interventions. Community members working together is the best line of defense to extreme events and can leverage and fill in with the outside interventions.

Top photo: Soldiers with the Texas Army National Guard move through flooded Houston streets as floodwaters from Hurricane Harvey continued to rise Aug. 28. More than 12,000 members of the Texas National Guard were been called out to support local authorities in response to the storm. Photo by U.S. Army photo by 1st Lt. Zachary West [Public domain], via Wikimedia Commons

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ASU engineer on rebuilding after a hurricane: First, sweep the porch

September 7, 2017

Starting small is key to disaster recovery, says expert who lived through Katrina and created a firm to help rebuild New Orleans

When Tony Lamanna bought his home in New Orleans, the civil engineer discovered a hatchet in the attic. The hatchet was stored there to chop an escape hole through the roof if the house flooded up to the attic. It’s a Gulf Coast precaution. When he sold the house, it stayed there.

Lamanna, now an associate professor in Arizona State University’s School of Sustainable Engineering and the Built Environment, was teaching at Tulane University when Hurricane Katrina hit New Orleans in 2005.

When Tulane started shutting down its engineering programs, Lamanna stayed and started an engineering firm to assist rebuilding the city. His expertise eventually grew to encompass building repair, rehabilitation, retrofit and adaptive reuse.

Like the rest of the nation, he watched this past month as Hurricane Harvey slammed into metro Houston, covering 70 percent of Harris County’s 1,800 square miles with 1.5 feet of water, killing about 50 people, damaging or destroying 200,000 homes and displacing more than a million people.

“This is going to be a massive, massive cleanup process,” Texas Gov. Greg Abbott told “Good Morning America.” “This is not going to be a short-term project. This is going to be a multi-year project for Texas to be able to dig out of this catastrophe.”

Houston Mayor Sylvester Turner made a public plea over the holiday weekend.

“Over 95 percent of the city is now dry,” he told NBC News. “And I'm encouraging people to get up and let's get going.”

It turns out that’s the best advice anyone can give. ASU Now spoke with Lamanna about first steps and next steps. 

Question: Large-scale — you’ve got to get the power and water on before you do anything. What are the next steps after that?

Answer: There’s a lot going on there. Probably if your house was flooded the power company is going to pull the meter because they don’t want you just turning the power back on. You’re probably going to need a licensed electrician to certifty your house before they give you your meter back.

It’s “start inward.” It’s such a monumental task for cleaning up after. What do you do when the city is destroyed? The best piece of advice I got came from a friend of mine in New Orleans who is German. He had a mother who lived through World War II. She lived in Dresden, so the city was destroyed. What do you do? Take care of your house. Sweep the porch. Sweep the debris. Fix what you can fix in your house. Then you help the neighbors with their house. Then you help the neighborhood. And you just go out from there. You have to start small. This is what happened in Katrina. You see it when there’s disasters ... there’s going to be some level of shock there, but you have to start doing something.

Q: What are city officials looking at at this point? They want to get the trash picked up, all the debris that has been hauled out to the curb.

A: There’s going to be staging areas. In New Orleans they have West End Boulevard where they just immediately piled everything. ... After Katrina there were houses in the middle of the road, so you had to get stuff cleared to move through the area. They need to have first responders able to get to people, so they’re clearing a path.

They’re checking out their infrastructure. A lot of neighborhoods flooded after the fact because they had to relieve pressure on levees.

Q: There was still flooding as of this week. People are still getting flooded out.

A: That’s probably their number one concern right now, that they don’t have failure in the infrastructure system, in the water control system. If a levee goes, everyone gets flooded. So it’s right now it’s selective flooding to relieve pressure. I’m pretty sure the backs (of the levees) aren’t armored. You armor the front for water lapping up against it. Often the back side only has grass. If it overtops, it’s going to erode. It’s funny because the Army Corps considers grass to be armor.

Q: The governor of Texas said it’s going to take years to recover from this. Is that accurate?

A: Actually it might be even more because of the magnitude. The metro New Orleans area when Katrina hit was 1.5 million (people). What’s Houston — 6.5 million? And this is not just Houston; this is Beaumont, Port Arthur, this is major.

Officials are probably focusing on infrastructure right now. As much as they need to take care of residents, getting the port facilities back in business, getting the business infrastructure back in place is important. Getting the schools open; after Katrina, most schools didn’t think about opening for a semester, let alone a year. ... Schools are important, because you’re going to start losing professionals who have kids. ... That’s a big thing.

Q: There’s talk of buying people out and not letting them build in certain areas.

A: This is another discussion. Part of the puzzle is what do you do next? It’s politically insensitive to say, “We’re not rebuilding that area” in general because those areas tend to be poorer. ...

I feel that could potentially be a plan for next time, that we don’t rebuild certain areas. You make the plans now for the next time, because you’ve got these large swaths of the city where we’re providing police protection, fire protection, and you’ve got the infrastructure, water, sewer and very few residents. I think there’s an opportunity — not for this time, but for next time — for Houston to say, “We need to further develop this spillway; when the water gets high we can open it up and flood these grassy plains or baseball fields or something,” and not allow construction there.

Answers edited for clarity and length. Top photo: Flooding in Port Arthur, Texas. Photo by SC National Guard (170831-Z-AH923-023) [Public domain], via Wikimedia Commons