When CNN news reporter Soledad O’Brien took a walk along the top of the new storm surge barrier known as the West Closure Complex (WCC), the structure stood in the immediate path of 2012’s Hurricane Isaac as it grudgingly made it way toward the Gulf Coast. Pausing offshore for days, as if sizing up the city’s newly minted defenses, the tropical cyclone’s low-pressure core sucked up a huge mound of ocean and pushed it toward the city in the form of a storm surge. Impelling a surge with an elevation just 1 foot shy of the record-breaking wall of water Hurricane Katrina flung at the city, Isaac took his best shot.
What would become of brand-new coastal armoring, surge barriers, and modified levees and pump systems facing their first real threat? Beneath the bulwark from which O’Brien reported, a complex of 11 Caterpillar C280 5,400-horsepower engines were being readied to power massive pumps designed by Fairbanks Morse to eject rainwater collected from nine separate outfall watersheds, away from vulnerable areas of New Orleans and back out to the Gulf. To ensure the surge could not find its way into the city from any vector, two additional new storm surge gate complexes known as the Lake Borgne Surge Barrier and the Seabrook Floodgate Complex were also being prepared for lockdown. The system, designed to prevent the surge from entering the interior parts of the greater New Orleans area, represents a new and essentially revolutionary approach to the city’s hurricane preparedness infrastructure.
When Isaac struck, the gates closed to maritime traffic, sealing off New Orleans’ ports from the outside world but more importantly barring the incoming storm surge from entering the shallower channels leading to the city center. It was in these channels that the storm surge had been allowed to build up during Katrina, with the water carrying enough momentum to breach damage and destroy levees and flood walls at about 50 separate points near the interior of New Orleans during that catastrophic event. During Isaac, the levees of New Orleans would see no such onrush from the sea.
Wendi Goldsmith says that as the storm passed through, it soon became apparent that the major news bureaus would quickly cut away. That was good news: The various components of the Hurricane Storm Damage Risk Reduction System (HSDRRS) performed as designed. Hurricane Isaac rolled over New Orleans and went on its way, leaving the city soggy but not devastated. There was some flooding and some pockets of damage, but nothing that would amount to a disaster, much less a catastrophe comparable to what occurred when Katrina came ashore. Even though General Michael Walsh, the retired former commander of the Mississippi Valley Division of the US Army Corps of Engineers (USACE), concedes that water made it to “the top of the barriers,” the closure gates held at bay Isaac’s massive storm surge, and the threat to heart of the city was averted. The aftermath of Isaac did not make for good television.
But Goldsmith, now director of the Center for Urban Watershed Renewal, says the tenth anniversary of Katrina is part of a much bigger ongoing story. Goldsmith and Walsh agree that the passing of Hurricane Isaac relatively peaceably through the New Orleans area marked the seeding of success of a new concept and approach to public works infrastructure projects. It marked the triumph of the first major regional-scale resilient infrastructure project completed in the United States. The new approach, Walsh says, carries the official term risk reduction, but Goldsmith says it is inspired by the concept of resilience.
Redefining Risk
As the former owner of Bioengineering Group Inc., the firm that in partnership with Arcadis oversaw the design of and planning for New Orleans’ HSDRRS, Goldsmith was lead engineering consultant to the USACE for the roughly $15 billion project to strengthen the city’s infrastructure response to hurricanes and tropical storms, with the aim of ensuring a disaster like Katrina would not happen again.
Having sold her stake in the company, she reflects that the firm’s success in the leadership position on the HSDRRS multi-firm team could be traced, in large measure, to “Bioengineering Group’s commitment to weaving climate change, sustainability, and resilience into the design work they performed on numerous previous projects” for clients ranging from the city of Boston, to the US Army Corps of Engineers.
Although she says the concepts of climate change and sustainability have widening exposure and widening application in infrastructure projects, the concept of resilience was fairly new to the engineering community when the post-Katrina HSDRRS project began.
“Resilience was not a word that was in vogue at the time,” says Walsh, former president of the Mississippi River Commission and former commander of the Mississippi Valley Division of the USACE, the key federal partner in the design and construction of the HSDRRS. Now he serves as vice president of water resources/coastal resiliency with the engineering consulting firm Dewberry Associates.
Goldsmith felt when the project began that people in the engineering community had varying takes on the meaning of resilience. She took a survey at that time “to find out what members of the team thought the term resilience meant.” In engineering in general, she says, “The predominant way the term was understood came from the field of materials science,” as a descriptor of the strength of a substance, while the most frequent response from the team members was, “When we design a flood wall so it won’t wash out—so that a heavy impact on levees won’t cut through.”
Goldsmith adds, “The resilience of the elements of the system was the main way people understood the concept.”
As an inspiration for the work on New Orleans’ coastal defenses, she proposed that the term held a deeper level of meaning. In contrast to many terms that have come in and out of style in policy discussions, she says, resilience is more than just a catchy phrase to cover ever-changing concepts. “The most appropriate concept to understand to define resilience is positioning yourself to be better in the future. It’s the ability to bounce forward, not backward.” And no place needed that ability more than New Orleans after Katrina.
She says there were engineers in the planning phase who proposed putting things back the way they were, “only better.”
Noting how much went wrong in the aftermath of Katrina and the catastrophe caused by failures of hurricane barriers and levees in 50 separate instances, she says, “It became clear that putting it back the way it was would not be the right answer.”
She adds, “Part of that is understanding that the future will not resemble the past. But that today—it will be very different from the past.”
Lake Borgne Surge Barrier
Wetter, Hotter, Drier
Goldsmith’s perspective is not based on speculation, but science. For example, scientists, such as Nobel Prize-winning Kevin Trenberth, of the National Center for Atmospheric Research, agree. In his groundbreaking paper “Changes in Precipitation with Climate Change,” he describes the effects of climate change on peak precipitation patterns. Relying on math and physics such as the Clausius-Clapeyron equation describing the water-holding capacity of the atmosphere as a function of temperature, he predicted a roughly 7% increase in moisture capacity in the atmosphere for every 1°C rise in temperature.
With the warming climate the planet is experiencing, that equates to heavier rain when the atmosphere reaches the dew point. But in addition, Trenberth wrote, odd things will happen too with climate change. He predicted that areas that receive this increased precipitation will often end up with increasingly drier soil. That’s because the heavier rains will be more episodic and concentrated in time, within more intense downpours, and the water will be more likely to merely run off before it has the time to percolate down into the ground.
“The paleo-geological record, and now the models, all confirm the big gully washer storms are going to happen not just in the southern tier of the United States but in many regions that have not historically seen that kind of climate,” says Goldsmith.
Under these conditions, she notes, there will likely be challenges wherever stormwater infrastructure exists. “The peak 24-hour rainstorms will overwhelm storm drain pipes. Where 40 years ago a single pipe would suffice to provide proper drainage, now you’d need two pipes because the rain has changed.”
Tom Knutson, research meteorologist and climate scientist with the National Oceanic and Atmospheric Administration (NOAA), agrees that “the future will be different from the past.” He says NOAA has made a lot of progress in the 10 years since Katrina on researching storms in the Atlantic Basin with broad simulations and with “pretty good data,” building confidence in what the climate models predict. In accord with the models regarding hurricanes during the current century, he predicts “fewer storms overall in the Atlantic, but more of the most intense variety, such as Category 4 and 5 storms, with rainfall rates 5 to 10% more intense on average by the end of the 21st century.”
With these coming changes in mind, Goldsmith says, “Resilience is not a about achieving a target that is known and defined, and knowable and definable. Resilience, ultimately, is about being prepared for all the things that you think can happen—including being prepared for some surprises.” She gives an example of the type of surprise that might seem probabilistically unlikely: “What if Hurricane Sandy hits at high tide, when the moon is full, and it’s got the highest storm surge ever recorded in the north Atlantic? What are the odds of that happening at the same time? Well, it did.”
Going Full Circle
After a series of catastrophic floods in the region, during the 1960s Congress began appropriating funds to build New Orleans’ defenses.
Before Katrina, the labyrinth of levees, complexes of pump stations, and floodgates weaving through the greater New Orleans region didn’t even have a real identity, Walsh notes. Not to say it was ineffectual—it had doubtless saved many lives. However, Walsh calls it “a system in name only.”
According to Walsh, this “hodgepodge” resulted not from a lack of imagination or lack of noble intention, but rather from social dynamics in the competition for resources and the vagaries of the appropriations processes. Although it was before his time with the USACE, Walsh says the funding mechanism was inconsistent, making it incompatible with a systematic approach to hurricane defense.
“Some years you’d get $10 million; some years you would get $2 million; sometimes you’d get more than that,” he says, but there was never enough to complete the defenses. However, he says, if New Orleans’ hurricane protection had been built under circumstances and processes that allowed its fruition prior to Katrina, “it could have mitigated some of the disastrous impacts.” Nonetheless, he concedes there still may have been some serious problems related to other factors. For example, “Over time the engineering criteria had changed from T walls to I walls,” which led to some of the engineering challenges the levees faced during Katrina.
Referring to the constituent parts at varying stages of completion or levels of repair, Goldsmith notes, “If you have a whole bunch of links of a chain on the floor but nothing to connect them, you don’t really have anything that you could call a system.”
What New Orleans and the rest of the nation needed, then, was not just to repair, retrofit, or replace existing inadequate infrastructure, but also to connect the links to meet an achievable goal—and it needed a reliable and timely process for getting it done.
Walsh says the successful completion of the task was the result of three key decisions. First, Congress voted “to fully fund the project up front. That meant you could put a design together that you can complete in the shortest time possible.” The second decision was to streamline the environmental review processes through an abbreviated National Environmental Policy Act (NEPA) compliance process, which meant the USACE did not need to propose a plan to mitigate each and every environmental impact before the construction could begin as is done for most projects, but that the agency could keep track of the environmental impacts and mitigate them as the project proceeded or even after the project was completed. Finally, the entire mandate was backed up by the Presidential and Congressional mandated goal of achieving 100-year protection in place by June 1, 2011.
The HSDRRS transformed the hurricane damage mitigation mindset. The previous flood protection paradigm, which Walsh terms parallel protection, essentially envisioned that each jurisdiction facing flood risks would build up levees and flood protection infrastructure along the banks of the various channels and canals passing along the reaches under their jurisdictions. Each of the respective municipalities’ authorities would seek to build higher and higher levees and flood walls, with the expectation and hope that neighboring jurisdictions would find the resources, the willingness, and the capacity to follow suit and extend the line of defense, lest they be outflanked by a weakness somewhere else along the waterway. It was a piecemeal approach, and Katrina demonstrated its shortcomings.
As an alternative to the uncertainty and the hundreds of more miles of levee, flood control infrastructure, and flood wall construction that would be required for parallel defense, Walsh says, the HSDRRS introduced the groundbreaking strategy of perimeter protection, essentially drawing a circle around the vulnerable greater New Orleans area and planning a contiguous flood control structure with components selected, designed, and operated to tame the storm surge. Pumping stations on the interior of flood walls would send accumulated rainfall downstream of the surge barriers so as to mitigate flooding behind the storm surge barriers due to rainfall, giving New Orleans the capability to withstand the 1% likelihood storm with a mere 137 miles of levees.
Walsh says, “I’ve always looked at it as a systems approach, and there’s not one part of the system that is more important then another. It had to all go in at the same time to protect the city by 2011.”
Bouncing Forward
According to Goldsmith, the new process first required a change in perspective on what any infrastructure, no matter how well planned or executed, can achieve against an opponent as formidable as nature and her storms. “It’s even designed to fail in ways that will not be catastrophic,” she says. “A failure in one area won’t take out the whole system.”
As one example of increasing resilience and reducing risk by relying on multiple layers of defense, the levees along the Inner Harbor Navigation Canal, Algiers Canal, and the outfall canals, which in many places failed catastrophically during Katrina, have been relieved of the duty as the first lines of defense during tropical cyclones. Under the new system, when the sea wall closure gates at the seaward edges of the metro area are sealed at the approach of a storm, these levees in the interior of the metropolitan region’s developed areas take on a redundant secondary role in reducing the risks of flood damage.
Goldsmith says the system is designed to accommodate growth into a third or fourth layer of redundant lines of defense. “It already benefits from a multiple lines of defense approach,” she says, and the risk levels could be lowered further, “not by making the flood walls higher or stronger, necessarily, but another way to do it is with dunes and barrier islands and lowland forests, back-levee in addition to fore-levee, and flood walls, additional pumping capacity—there are lots of ways to help manage risks.”
Ten years after Katrina, work continues to armor the landward side of the levees with deep-rooting vegetation, while three temporary pump stations installed in the aftermath of Katrina are slated to be replaced with permanent stations as the overall project nears completion.
At the conception of the system in April 2007, Goldsmith says, designers were compelled “not only to consider historic data, but also to consider how the elements would work individually using probabilistic forecasts, not based on today’s climate but based on the best knowledge for 100 years out. It is wise to think even further out than 100 years—but it’s a good start.” Acquiring the best knowledge possible about future conditions, she says, is the best route toward arriving at a resilient future. To bring the point home, she says, “You don’t drive looking in the rearview mirror.”
Costs and Effects
A resilient New Orleans is beneficial not only to the residents, families, and associates of people who live in the Gulf Coast region, but also to the millions across the United States and internationally who rely upon the exports, commerce, interpersonal connections, and culture that emanate from the city and its ports.
Yet the quandary of who should bear the costs of creating a resilient New Orleans remains a question. Complex negotiations continue over the financial packaging of maintenance and operations for components of the HSDRRS, such as operation of the WCC. While the direct beneficiaries of the HSDRRS are the residents of New Orleans and the communities behind the control structures, many of the elements offering the protection reside beyond the jurisdictional boundaries of the city, raising the question of who should pay for their ongoing operations. By 2014, local news outlets in New Orleans were reporting that issue had yet to be definitively decided. However, late in 2014 an agreement was reached that provisionally assigned responsibility for operating the WCC to the Southeast Louisiana Flood Protection Authority, splitting costs with Plaquemines Parish, while negotiators worked on devising a suitable long-term cost-distribution arrangement.
General Merdith W. B. “Bo” Temple, who was acting commander of the USACE when the HSDRRS reached its FEMA-mandated 1% storm protection goal in 2011, endorsed the idea that some of the system maintenance costs could be sustainably self-financed through the installation of multi-modal enhancements. Goldsmith agreed, proposing that a built-in funding source would represent an added level of resiliency. They suggested enhancements such as wind turbines at selected sites along perimeter levees and flood control structures in the Chalmette Loop as a means of helping to finance the management and operations cost for the infrastructure. In an article authored along with Goldsmith for The Military Engineer, Temple highlighted proposals to install a system of wind energy turbines along the levee walls to generate electricity for sale to the grid. He also supported the concept of periodic harvesting of biomass in the form of switch grasses, from armoring grasses planted to strengthen levee walls. He wrote that these biomass sources could serve as feedstock for coal-fired power plants. These kinds of public-private partnerships, he said, could serve the dual purpose of promoting financial resiliency for the HSDRRS while helping address directly the region’s contributions to greenhouse gas emissions.
Walsh, noting that these multimodal enhancements have not been undertaken, likely due to the financial climate at the time the system was being constructed, indicates that finding a long-term solution to financing resilient infrastructure for New Orleans and beyond will require a process of political and philosophical evolution. However, he suggests that certain policy initiatives could help push resources in a more favorable direction for bringing such enhancements to fruition.
He believes some of the financial benefits that accrue for property owners in areas where risks have been reduced, such as lowered insurance premiums or increased property values, could be directed toward funding the initial installation of revenue-generating enhancements that might help sustain their operation and maintenance.
However, Goldsmith believes the financial justification for supporting the infrastructure is built in. Citing the success of the system in meeting the challenge of Hurricane Isaac in 2012, Goldsmith says an unpublished analysis indicated the potential for losses in the range of $30 billion in damage from storm surge had the system not been in place. In light of the fact that the storm surge barriers and other risk reduction infrastructure prevented the storm surge from building up to dangerous levels, Goldsmith says, the $15 billion investment in the HSDRRS has already established an almost two-to-one return on investment.
Walsh believes it is “important to continue discussion on the word resiliency. People clearly recognize, through dozens and dozens of cost-benefit analyses, that an ounce of prevention is worth a pound of cure. Most of the analysis shows that if we were to put in resilient infrastructure, it would be at least a four-to-one return, and in some cases a seven-to-one return and 10-to-1 return, but people have to make a priority decision whether they want to put in that particular infrastructure. Typically, our taxpayers don’t want to pay that additional funding to get their infrastructure to a resilient state.”
In contrast to the city’s previous hurricane protection infrastructure, “HSDRRS functions as a system,” says Goldsmith. “The HSDRRS prevents the largest storm surge from even forming,” much less funneling a cascade of water toward the city, as happened during Katrina. Although no system can guarantee absolute immunity from all risks, even vocal critics agree that the current level of protection exceeds anything New Orleans has had in the past. Beyond that, Goldsmith says, it provides a model and an example of what can be accomplished through a systematic methodology for public works projects of various types focused on risk reduction and resilience.
A MIRROR TO THE FUTURE
What is not widely known is that in 2013, Hurricane Katrina struck New Orleans for a second time, more than a century before the first strike. It doesn’t sound logical, but it was almost entirely based on logic—and fortunately, no one got hurt. It happened in a test tube—or in a NOAA computer simulation, to be exact—so there was no real damage, either. But the results were revealing and instructional for what the rest of the world can expect as sea levels rise and tropical storm intensification continues.
In 2013, researchers at NOAA took a sobering look into the rearview mirror, proving that future risks to coastal communities will rise considerably, even if the increases in tropical storm intensity predicted by some climate models are not replicated in the real world.
They found that the dominant factor increasing risks to life and property as a result of hurricanes and cyclones will be sea level rise, a documented and ongoing phenomenon that is not predicted to abate during the current century. In fact, Tom Knutson, scientist and researcher with NOAA, says that even if human contributions to climate change were to come to a sudden halt, the lag in time over which melting sea ice and thermal expansion would take to respond would mean that sea levels would continue to rise for centuries.
To examine the impact of documented trends in the geophysical realm on the future of coastal society, researchers populated a laboratory model of New Orleans with defenses identical to those in existence in 2005, then put it in the path of a modeled monster storm. Moving through the geophysical realm programmed to conditions that would have prevailed in the region in the year 1900, the storm met the levees as they existed the day before Katrina. To fill out the tests of the lab-generated copies of the storm, the modelers prepared several scenarios through which Katrina’s hypothetical Gilded Age ancestor would traverse.
As Seas Rise, Lands Subside
In an attempt to tease out the effects of trends due to climate change such as sea level rise and increasing storm intensity upon the severity of risks for coastal communities, they ran the model under varying scenarios. In one instance, they varied the conditions within the environment of the storm itself to mirror the predicted reduced intensity that a storm with Katrina-like characteristics would have had under the cooler climatic conditions worldwide at the turn of the previous century.
In the series of model simulations where researchers entered the cooler temperatures and climatic conditions that prevailed in 1900, the hurricanes generated were indeed weaker and their storm surge levels less severe than Katrina’s. In yet another run of the simulations, the researchers varied the amount of sea level rise entered into the model from the actual 0.75-meter rise experienced since 1900 in the New Orleans region.
In one of the runs, they omitted the prominent factor of land subsidence of 0.57 meter in the New Orleans area, arriving at a sea level rise of 0.18 meter for this model, equivalent to the global mean sea level rise seen since 1900 around the world. This simulation provided a generalized view of the consequences of sea level rise to date globally. In another run of the model, they combined the contributions of global sea level rise with the local sea level rise, against the backdrop of a storm without the enhancement of the higher temperatures seen in the current era. To round out the worst-case scenario, they presented the historical hurricane Katrina of 2005, in which all of the factors of increased storm intensity,land subsidence, and sea level rise combined, to deliver well-known tragic results.
Looking back and computationally deriving the likely broader extent of marshlands and coastal barrier islands during periods prior to accelerated sea level rise, they theorize that the welcome mat for Katrina circa 1900 would have been a lot longer, with a plush deep pile of coastal vegetation, providing friction and giving the storm ample opportunity to wipe its feet of the dirty business of storm surge before reaching the constructed flood protection barriers. The wider expanses of wetlands and coastal vegetation that researchers presumed would have been present 100 years ago would have applied enough friction to dissipate the energy of the surge.
The simulation demonstrated that even without the increased storm intensity predicted by some climate change models, hurricanes and tropical cyclones striking the coasts anywhere in the world in the future will have the potential to prove a lot more devastating than they are even today. The model showed that sea level rise, and not heightened storm intensity, would bear responsibility for the bulk of the increased risk. The researchers concluded, “Increases in flood elevation for a certain storm may greatly exceed sea level rise for a given region.”
Further, the simulations demonstrated that no increase in storm intensity is required to result in significant increases in flood risk to coastal zones under current sea level rise scenarios.
Under conditions that existed a century ago, they concluded, Katrina could have had a much less devastating impact.
New Orleans’ situation, their paper points out, will likely continue to be exacerbated by the sum of continuing local subsidence due to highly active natural geologic processes in the region and human activities such as subsurface oil and water extraction, levee building, and other construction.
FORECASTING FOR RESILIENCE
Given society’s pronounced preference for habitation along coastal zones, additional Katrina-like incidents are not beyond the realm of possibility. But NOAA has added capacity since Katrina that is intended to help make the communities and people who live and work along US coastlines more resilient. According to an agency spokesperson, NOAA has significant supercomputing power to improve forecasts and climate models.
Some of these enhancements include the first Graphical Tropical Weather Outlook and storm surge probabilities, introduced into NOAA’s forecasting capabilities in 2007. The agency increased forecast precision, and in the 10 years since Katrina has extended by 12 hours the tropical cyclone watch and tropical cyclone warning lead times. Pushing forward the tropical cyclone watch from 36 to 48 hours in advance, and providing warnings from 24 to 36 hours in advance, will grant policymakers and the public valuable additional lead time to take appropriate precautions. Adding geographic precision to its forecasts, NOAA’s National Weather Service has narrowed the “tropical cyclone forecast cone” by 40%, providing a significantly more accurate track of the center of a tropical cyclone than existed during Katrina’s approach.
In 2013, NOAA extended the Tropical Weather Outlook from two days to five days. In 2014, the agency introduced the Potential Storm Surge Flooding Map, which it says will continue experimentally along with a Prototype Storm Surge Watch/Warning graphic, each of which can help communities take the correct precautions in the face of approaching storms.
