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VOL. 41 | NO. 24 | Friday, June 16, 2017

Avoiding the next big Nashville flood

Climate change is bringing more-intense storms. Where can that water go?

By Holie Deese

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Areas of excessive water, ponding and flash flooding after a heavy storm in Middle Tennessee bring back memories of Nashville’s 2010 devastating flood.

The pools of standing water and storm run-off are more than reminders of the flood for Janey Camp; They also are data.

A Vanderbilt University research associate professor of civil and environmental engineering, Camp is part of a team of engineers with research grants to study commerce and flood control on inland waterways.

With U.S. Department of Housing and Urban Development funding, Camp, along with Mark Abkowitz, director of Vanderbilt’s Center for Environmental Management Studies, has been studying people who have built their lives along the levies of the Mississippi River.

Deploying web-based tools called Geospatial Information Systems, or GIS, to look at and analyze climate projection data to identify areas and infrastructure that may be at risk for more or heavier precipitation in the future, the Vanderbilt team is mapping West Tennessee flood vulnerabilities under future climate scenarios.

The tools will eventually be available for use across the country, including Nashville.

“If you drive around Nashville, you can often see pooling,’’ Camp points out. “Sometimes it’s because the drains are clogged with debris or something like that. But the other piece of that is they may not have been designed to handle the amount of precipitation we’re getting in a short period of time.

“We’re starting to see more of these short-duration, intense storm events, which lead to more short-term, after-rain events – flash flooding, or a lot of runoff, because the ground just can’t hold it.”

Part of Camp’s job is to help people understand how the research she is working on at Vanderbilt can apply locally, like in the rapidly growing Nashville area where more hard surfaces means more storm-runoff, which can lead to potential failure of infrastructure or disruption to normal operations.

One project the team is working on is a potential home buyout program for Metro Water, which purchases homes in known flood plains. They are working to determine the benefits of that program, not just in perks or reduced losses by homes being damaged, or infrastructure being damaged, but the community or ecological benefits from converting homes back to green space.

“To some extent converting those to green space allows more opportunity for water to infiltrate, as opposed to just running off and getting into these drains or causing localized flooding in an intense event,” Camp explains. “I know Metro is working on low-impact development guidelines, and they’re really working with the developers to reduce the amount of run-off leaving a site.”

Runoff can take with it chemicals, waste, garbage and more. She says she hopes Nashville’s positive flood recovery doesn’t deter from the facts.

Janey Camp’s tablet shows a map that displays an example of a Nashville flood analysis for the downtown area near the Cumberland River.

-- Michelle Morrow | The Ledger

“But then, Nashville responded really well [to 2010 flood]. So, we may have a false confidence that if we get hit again, we will pull together as a city and it won’t be that bad,” Camp adds. “But, who’s to say as we have more development, it wouldn’t be worse because it’s more runoff that contributes to floods.”

Science won’t stop

Vanderbilt’s Hiba Baroud is leading a project funded by the National Science Foundation focused on using Bayesian statistical modeling to measure and analyze the risk, reliability and resilience in critical infrastructure systems; in particular, to predict outcomes in extreme weather events and models of how communities can most quickly recover. Mostly focused on infrastructure systems before, during and after a destruction, she looks at how an infrastructure system responds and recovers.

“With the recent increase, and the frequency, and the magnitude of natural hazard events lately, people started shifting from risk management towards resilience,” she adds. “Those events are happening. A lot of times we won’t be able to stop a hurricane or flood from happening. So infrastructure operators and decision makers are now thinking more about how to design and build future infrastructures that will be able to actually recover more effectively.”

A project she is currently working on for Nashville is solely related to growth, trying to assess the delay in transit – given things like traffic and other events such as the CMA Fest and Stanley Cup playoffs that are drawing more visitors.

Another of her projects is in Memphis in Shelby County, looking at how communities could be responding to potential hazards caused by an earthquake or by flooding.

“Those could impact the power, the water infrastructure, or transportation, and so how do communities impacted by these events, how do they recover? And what is the best way to quantify those impacts? So, that’s where the research challenge is, in being able to collect and have meaningful data that will be suitable for the types of models, or at least for the other way around,” Baroud says.

Since her work is directly focused on infrastructure, Baroud explains she hopes it will not be impacted by Trump’s withdrawal from the Paris climate agreement, but she is concerned about the impact if Americans don’t acknowledge that the weather events we are seeing in the last decade or so are not the same type, and the same frequency, of events that we saw previously.

“The infrastructure is not able to withstand such events because this infrastructure was built 50 years ago based on measures and metrics forecasted for a climate the engineers had back then,” she continues. “If we want to build future resilience systems, then we need to acknowledge that we are facing risks and hazards that did not necessarily exist in the past. Those could come from things like climate, but they could also have other sources. But at least when we are thinking about building better infrastructure, we are thinking we want these infrastructures to face a climate that is changing.”

Hiba Baroud, an assistant professor at Vanderbilt University, studies how infrastructure systems respond and recover from disasters.

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East Tennessee also is dealing with some concerning numbers coming from Climate Change Science Institute at Oak Ridge National Laboratory where data developed shows that by 2100, Knox County could have 20-80 more days when the maximum temperature is above 95 degrees Fahrenheit. The higher and lower number of days are correlated with higher and lower emissions.

Because a warmer atmosphere holds more water, a rise in temps could cause more winter precipitation, and with Knoxville’s steep hills, that could lead to rapid runoff and more flash flooding.

Oak Ridge National Laboratory was recently paid a visit by newly-appointed Secretary of Energy Rick Perry, who promised to be a strong advocate for the facility. The visit was just days before Trump’s withdrawal from the Paris Accord, and one day before Trump’s proposed budget for the fiscal year 2018 that includes a possible $185 million in cuts to ORNL.

If Trump’s budget request is enacted, the lab’s funding would drop from about $1.247 billion in Fiscal Year 2017, which ends September 30, to roughly $1.062 billion, a decrease of roughly 15 percent.

As for now, it is business as usual at ORNL with continued research that deals with regional and local communities and extreme weather.

“Right now, our budget hasn’t been cut and our researchers are continuing their work collecting and analyzing data to improve understanding of climate systems,” says David Keim, director of communications for Oak Ridge National Laboratory. “We can’t speculate about what might happen as the fiscal 2018 budget works its way through Congress, and the Paris Accord is a policy matter, which is outside our area of responsibility.”

Regardless of what may happen with the withdrawal from the Paris Accord, Camp says it does affect in some way their research and the public mindset.

“It’s hard to say exactly how, but I think the implications are far-reaching, and we may not even realize what those implications are at this point,” she adds. “It’s concerning to me. Not just in terms of overall global climate change and our contributions and what this might mean, but just the ramifications of us as a leader among nations and the international relationships.

“And it will affect our research because we work on interdisciplinary projects. We have collaboration at Vanderbilt that reaches beyond our borders.”

Camp grew up in rural Tennessee and says she has talked to farmers who think climate change is a hoax. But when asked if their growing season has changed or if they have seen more flooding and droughts, they agree – especially older farmers – things are different.

“It’s hard to explain these big global models and how it relates to the very localized scale,” Camp adds. “And so that’s some of what we’re trying to do, is bring that information to a localized scale and use that localized information to help people make decisions and understand the impact.

“The changes and the impacts are most seen and felt at the local level. It’s not one person in D.C. making decisions, it’s every individual and their decisions and how it contributes to greater good.”

Abkowitz, director of Vanderbilt’s 25-year-old Center for Environmental Management Studies, notes that over the years the school has become much more multi-disciplinary, evolving from a singular focus on engineering as a solution to the world’s problems to realizing those problems require a seat at the table from engineers as well as scientists, policy analysts, lawyers and business owners and other stakeholders.

“If we’re going to solve these problems, we have to make sure that those folks are all engaged in the process,” he explains.

Abkowitz doesn’t even say “climate change” anymore, opting instead for “extreme weather” – it’s more relatable and more accurate when talking about excessive heat, flooding, wildfires or heavy storms. But regardless of the words, it’s the actions of the weather that are all too real.

“Let’s suppose that there is no climate change going on at all, but because we’ve allowed people to build in what have always been riskier areas, when we have an extreme weather event, the consequences are much worse because people and businesses have positioned themselves in locations that they should have never been allowed to be,” he says.

Go one step further, he continues, and you can suppose the climate is changing, but man has nothing to do with it. The third position is to acknowledge that the climate is changing, and humans do have a hand in it.

“My position is that you have to be in one of those three camps because there is no other place to be,” Abkowitz adds.

If the government is not paying attention, businesses are. In terms of enterprise risk management, so businesses look at anything that could go wrong that has an impact on their vitality. And so, a lot of it has to do with where they’ve located their facilities, or how their supply chain moves.

“That’s all affected by, among other things, natural hazards,” Abkowitz says. “And I think you’ll see some states and local communities also recognizing that these are things that they need to think about. And there are a lot of local communities, including Nashville, from what they experienced in 2010, that have come to the realization that you can’t rely on yesterday’s assessment of what kind of danger they might be in from these things.”

Abkowitz and his team recently completed an extreme weather vulnerability assessment for the Tennessee Department of Transportation, looking at all the transportation assets in the state including railroads, waterway barge traffic, highway traffic, transit, maintenance facilities and a variety of other transportation assets.

Then they looked at what future extreme weather portfolios might look like, and on the basis of all that research, were able to identify those critical transportation assets that are most vulnerable to future extreme weather.

The substantial construction in Nashville is concerning.

“The more that you build up your infrastructure, there are fewer places for the water to drain,” Abkowitz says. “That water’s got to go somewhere. So that’s one of the things that I think is important in land-use planning.

“When you’re doing what we’re doing here in Nashville, [we must] make sure there are adequate ways to provide for the kind of drainage to prevent those types of situations from occurring.”

And ultimately, it’s why the researchers do what they do. To help.

“I work with people from computer science on the data collection and algorithm side, and I work with the science department on understanding the natural resources. And then I work with colleagues from civil engineering on the engineering systems side,” Baroud says.

“We are all essentially trying to solve one kind of big question – how engineering and science can help better serve the societies, and so each field or each discipline is trying to answer a piece of that question. But that’s all we’re kind of hoping to aim for, how science can help society.”

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