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Expert Q&A: Dr. Todd Bridges

Dr. Todd S. Bridges is the U.S. Army’s Senior Research Scientist for Environmental Science.  He leads research and applications for the U.S. Army and U.S. Army Corps of Engineers in the areas of sustainable infrastructure and environmental management. Dr. Bridges is the National Lead for the USACE Engineering With Nature® initiative, which includes a network of research projects, field demonstrations, and communication activities to promote sustainable, resilient systems.

By Amy Nelson

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Dr. Todd S. Bridges is the U.S. Army’s Senior Research Scientist for Environmental Science.  He leads research and applications for the U.S. Army and U.S. Army Corps of Engineers in the areas of sustainable infrastructure and environmental management.  Todd is the National Lead for the USACE Engineering with Nature® initiative, which includes a network of research projects, field demonstrations, and communication activities to promote sustainable, resilient systems. He led the focus on Natural and Nature-Based Features (NNBF) within the USACE’s North Atlantic Coast Comprehensive Study following Hurricane Sandy and currently leads an international collaboration to develop guidelines on the use of NNBF for coastal and fluvial systems. Todd is also the Program Manager for the Dredging Operations Environmental Research program, one of the Corps’ largest civil works R&D programs, where he directs the execution of more than $6 million in research annually.  He has chaired international working groups and guidance development for the United Nations’ International Maritime Organization and the World Association for Waterborne Transport Infrastructure, where he currently serves as Chairman of the Environmental Commission.

Generally speaking, what are the U.S. Army Corps of Engineers’ responsibilities when it comes to the nation’s coastal cities?

Directed by the administration and funded by Congress, the Corps of Engineers builds water resources and infrastructure on behalf of the public. We have a broad set of responsibilities related to projects that we construct in partnership with our non-federal sponsors at the state and local level.

The first infrastructure we built supported the American Revolution. With the formation of the country, our responsibilities evolved to include supporting maritime commerce and what we would now call national security to support navigation, ports, and harbors. Those responsibilities grew with time and with the country, and today, they encompass nearly $300 billion worth of U.S. water infrastructure to support navigation, flood risk management, water operations and ecosystem restoration.

When talking about nature-based solutions specifically for flood control, I understand that the Corps uses the terms “natural features” and “nature-based features.” For the benefit of our readers, can you define these terms?

To make a connection to the previous question, you might ask, “What is infrastructure?” In a 20th century context, infrastructure was associated with concrete, rock, steel, and asphalt. Today, it is inclusive of those things, but it’s a bigger concept. Engineering With Nature asks, “How can nature and its processes, systems, and structures, be functionally included as a part of the infrastructure systems we develop and operate?”

We derived the term “natural and nature-based features” in the aftermath of Hurricane Sandy. At that time, there was a lot of interest in these approaches to flood protection, but there were many different terms being used to describe them, which may have been confusing. People may have wondered, for example, “What is green infrastructure? Infrastructure that’s painted green?”  This was our attempt to come up with terms that were more specific. By natural features, we mean the features, landscapes, structures, and systems that Mother Nature builds and has built in the context of certain environments for millennia. They can take the form of islands, beaches, dunes, and wetlands, for example. These natural features provide a range of functions—including those relevant to engineering. A beach and dune constructed through natural processes, for example, provides protective, defensive, and risk management functions related to coastal storm surge and waves. An island or a network of wetlands can provide the same sorts of functions.

The Philadelphia District pumped 667,000 cubic yards of sand onto the beach at Brigantine, NJ, following Hurricane Sandy. Photo by USACE Philadelphia District

Nature-based features are features that that could be engineered and built to provide the same, similar, or even enhanced functions compared to natural features.  Say Mother Nature built a 20-hectare island that provides storm surge or waves attenuation benefits for a community.  In relation to future storm conditions and seal level rise, would expanding that island to 40 hectares through human ingenuity, action, and construction increase and sustain those benefits into the future? The largest and most mature example of this type of practice within the Corps’ portfolio would be beach and dune construction projects. This kind of work has been going on somewhat quietly in the U.S. for over 100 years. If you live in a beach community, you might likely be familiar with and understand the Corps’ beach nourishment construction projects, but I think a fairly large number of people within the country may be unfamiliar with that work and its value to the nation and local communities.

Engineering With Nature is celebrating its 10th anniversary. Can you tell us about the program’s origin, evolution, current direction?

We formally launched this initiative in 2010, and I have been asked on multiple occasions, “Why then?” My answer is, “It was time.” There are many examples of what we refer to as engineering with nature that go back decades within the Corps’ activities. That experience built over time within the Corps of Engineers. During that same time period, nature-based approaches to engineering and infrastructure were developing and taking shape in other places around the world.

One of our main goals with Engineering With Nature is to advance the practice by drawing from the lessons learned in the past so that we can make historically exceptional projects more commonplace in the future. Doing that requires a whole set of activities. There is research and development to build a solid foundation of science and engineering tools (because these kinds of projects must be based on sound technical practice, and not fairytales). We also need to demonstrate, in practical terms, that we can deliver such projects on a variety of scales, from piloting to full-scale projects. We have been doing that over the last 10 years with Engineering With Nature. Beyond all that, we need to communicate widely about these approaches. We’ve used a variety of communication mechanisms, including the Engineering with Nature Podcast, which we launched this year and plan to continue with a second season in the first part of 2021. Two years ago, we published the Engineering with Nature: An Atlas, and we’re getting ready to publish a second volume in the next few months. Combining natural systems with infrastructure can seem a bit esoteric to those unfamiliar with these ideas. The Atlas helps people —not just practitioners, but members of the public­—understand what these projects look like.  The ability to look at these projects and understand, through descriptions, how they operate makes them much more tangible and accessible.

When it comes to nature-based approaches to protecting urban shorelines, what have been some of the most important lessons that you’ve learned since launching Engineering With Nature?

There have been many lessons. One is to acknowledge and document the value being derived from natural features. We have more barrier islands by mile than any other country in the world, and they are delivering engineering functions that are relevant to flood risk management in many places around the country. These values are being produced by natural systems. That is a lesson we need to understand and appreciate. It certainly gives some motivation to conserve these natural systems. In addition to philosophical and value-based judgements about nature, these systems should be conserved because they are providing important engineering functions related to resilience.

When trying to justify a wetland creation project in a large, back bay region of one state, I asked the team, “If I could snap my fingers and make all of the wetlands that currently exist here disappear, would your flood risk management challenge be greater or smaller?”

Of course, that’s an easy question to answer, right?

We also are learning the importance of technical guidance. If we’re going to make investments in enhancing and promoting nature-based features, we need to know the science and engineering on which our strategies are based. This gets into the question of technical guidance and engineering standards and methodologies for exposing and substantiating the value that these investments can create. That is all work in progress. Over the last 100+ years, we developed some sense of confidence and practice for things like levees and seawalls, but you don’t just invent practice for natural and nature-based features in a blink of an eye.

In collaboration with Drs. Tori Johnson and Anna Wargula with the U.S. Naval Academy, Engineering with Nature is studying wave attenuation of coastal mangroves during extreme water levels at near prototype scales

Nature-based solutions are more dynamic, as well, so I imagine the science can take a while.

All infrastructure and features in coastal systems are dynamic, to different degrees. From an engineering point of view, the dynamics of nature-based features can be viewed as a challenge, but from an adaptation and resilience point of view, the fact that they are dynamic can be viewed as advantageous. For example, when a levee or seawall is damaged, it has zero capacity for self-repair. But given the right context, beaches, dunes, islands, and wetlands can and do self-repair.

Another lesson is the need for collaboration across organizational boundaries and disciplines to achieve these projects. The substantive collaboration required for progress does present a challenge.  For example, we are moving beyond protecting nature for nature’s sake, which was the philosophy at the beginning of the environmental movement. Now, we are talking about how to create an ally with nature in the context of engineering, so there is a need to rethink the approach that we take to environmental regulation and conservation activities. There is a policy element of this that needs to evolve in step with technical practice.

Where is the greatest need for policy change? What advice do you have for people who want to make that change happen to facilitate the integration of nature-based solutions?

I’ll give you a generic example. If I’m proposing an island habitat network to provide engineering function to protect a community, and it’s also going to have habitat function and value, that’s different than constructing an island purely to provide habitat or constructing an island and putting a condominium on it. I would submit that sometimes our regulations and policies don’t necessarily recognize this difference.

Much of our regulatory stance seems based upon what we can conserve. The intention is to hold the line to what the environment is right now or some historical reference condition or state. But with respect to sea level rise, climate change and other factors, there is no holding the line on the current configuration of nature. The idea is, “What tapestry of natural and/or nature-based features should we have to produce the most value (natural, engineering, and social) and function over time?” We are not going back to 1977 or some other historical reference point. That’s long gone. There are many places where our mindset about regulation and conservation, and the regulatory formulas we use, are not really up to the current challenges and opportunities before us.

What are some of the key factors that are proving to be critical to enabling the consideration of nature-based solutions into coastal protection or resilience projects?

There are many critical key factors. One is that you really need to work carefully, deliberately, and with some focus to develop sound engineering guidance and standards. Several years ago, a bunch of colleagues from several countries around the world developed the International Levee Handbook, which is a standard for how to engineer, construct, and operate levees. It is over a thousand pages, and it summarizes a practice, including lessons learned over several hundred years of experience. You don’t just snap your fingers and generate a comprehensive guide for natural and nature-based features, but we are going to publish a first effort at that, international guidelines on the use of natural and nature-based features for flood risk management, in the first part of 2021.

In addition to sound technical guidelines, you must have methods that allow you to reveal the full, diversified value, that such projects bring, beyond the engineering and economic value. The justification for an investment for flood risk management should include the engineering benefits related to flood risk management and the environmental and the social value that nature-based solutions provide. Doing that not only requires a methodology, tools, and concepts, but also policy that enables the use of these tools to recognize these more diverse value streams because some values are more easily monetized than others. This raises a whole number of issues. We have to become more skilled and experienced in revealing the full value that nature-based projects can provide to communities.

You also need space. For decades and decades and decades and decades, humans have built as close to the water as they can possibly get. This creates a tension point, because in order for natural and nature-based projects to work, you have to have space to build them. If all of that space is occupied by homes, hotels, et cetera, where are you going to build these projects? You don’t plant a two-foot wide garden of wetlands and get flood risk management benefits. Scale is important.

That said, one of the advantages of natural and nature-based features for flood risk management projects is that they can be phased. You don’t have to build all of the project at one time.  For example, a project to build a network of 1,000 hectares of wetland to provide flood risk management and other benefits can unfold over years, even decades. Of course, to do this you have to have a long-term plan for how you’re going to construct this over time, which involves long-term land use planning and urban development planning.

Nature-based approaches also require a lot of collaboration, cooperation, and partnering. That has to happen across multiple levels of government and across multiple agencies and entities. Collaboration fuels all innovation, and that is particularly the case here. Most people don’t have any trouble wrapping their mind around the broader value proposition of these kinds of solutions, but when you get into the specifics—especially when the path to delivering a project  involves having to adapt some existing practice or somebody’s pet process or organizational mandate— it can become very challenging when people focus only the risks and ‘downsides’ of change. There’s nothing easy about change, and that includes the way people think about these kinds of problems and opportunities and the pursuit of solutions in the form of policy and regulation.

Can you share an example of an effort that resulted in a change of mindset among policy makers?

Oh, very much so, and I think it illustrates some of the lessons we’ve learned in this regard. We currently have three (and anticipate more in the future) Engineering With Nature “proving grounds” in USACE that have made high level commitments to pursue these kinds of projects and approaches to infrastructure development: the Galveston, Buffalo, and Philadelphia Districts. To highlight an example… we have been working with Philadelphia District and their collaborators, partners, and stakeholders for several years to pursue these kinds of solutions in New Jersey, which was very hard-hit during Hurricane Sandy. That experience actually created new opportunities, because when you get hit like that, it shakes up the status quo. The hypothetical is no longer hypothetical, and that creates a kind of a mental pause where you think, “Hey, what can we do here?”

For six or seven years, we’ve been working with Monica Chasten and others at the Philadelphia District to find ways to implement nature-based approaches like using sediment dredged for navigation to restore degraded marsh and create nature-based features and wildlife habitat with state agencies and others. [Note: The Engineering With Nature podcast series includes a segment featuring Chasten and her work.] It has been amazing to observe the kind of the progress they have made, and the fairly rapid evolution from thinking in terms of, “I don’t know if we can do things like this because it seems so different” to demonstrating through multiple pilot and full-scale projects how it can be done.

There has been such an alliance created there over the last several years through a series of really substantive engagements, and meeting after meeting after meeting, where people are working across their organizational boundaries to understand what the opportunity is and try to figure out how to make progress.

Has it resulted in any policy changes?

I believe it has. The state has developed their own approaches to nature-based solutions and living shorelines. They recognize that they are going to have to evolve those approaches over time as experiences are gained, but the organizations that are collaborating in this progress are building first-of-their-kind projects in the state of New Jersey.

Many of us would like to see change happen instantaneously, but this is a lesson that positive change and progress is the product of diligent investment of time and energy. You don’t have a one-hour meeting and get there. You need years of persistent, positive engagement, and you’ve got to have the right personalities involved. People who are wired to say no to everything are a dime a dozen. You’ve got to find the people who know how to get to yes, if you want to change something.

Speaking of people, this issue is about urban coastal areas, and those areas involve a lot of people. Among its many collaborators, does Engineering With Nature include social scientists?

Engineering With Nature is a human enterprise. Most Engineering With Nature projects happen as a function of cost sharing arrangements within and among the Corps, the federal government, and state and/or local sponsors, so the peculiarities and idiosyncrasies of the individuals and organizations involved matter a lot. This is also true at the larger scale. Engineering With Nature can support communities, so it requires understanding what the community is looking for and is interested in investing in. The trend I’m observing, which I think is a very positive one, is an expectation on the part of the public for more value from infrastructure. The goal of delivering more value opens up the idea of multi-purpose projects, projects that deliver multiple streams of value to include environmental and social benefits. We also have to know how to reveal what values we are designing for and pursuing within these projects.

Nature-based projects can produce recreational benefits and improve the well-being of citizens.

I have great respect for the landscape architect, Frederick Law Olmsted, who, along with his colleagues, designed Central Park in New York and many other highly visible projects around the country. He worked with medical professionals in the 19th century to advocate for the poor within the Greater New York City area to come to Central Park because he firmly believed that contact with nature would be beneficial to their health and well-being. He was well ahead of his time.

We’re working with social scientists right now on an EWN project at Swan Island in Chesapeake Bay to help us understand how the people and the local community think about their future challenges and opportunities and what values nature provides to them.  The USACE Baltimore District restored part of the island that provides coastal protection for a local community.  The EWN project includes collaboration across several federal and state agencies to develop information on the engineering, environmental and social value this project is providing.  The need to integrate this diversity of information about projects is an important element of innovating and developing new approaches for infrastructure development.

Swan Island before (L, 2017) and after (LR 2019) sediment application

Sometimes the simple story can be as powerful as reams of data and in terms of reaching people. Might you have one to share that is related to an Engineering with Nature project that helps illustrate the social impact of a nature-based approach to urban shoreline protection?

I have a story that has to do with the hurricane of 1900 and Galveston Island, Texas. It was one of the deadliest storms in US history. The population of the island was on the order of about 40,000 people, and while estimates vary, it is believed that more than 8,000 people on Galeveston Island died during the storm. In fact, there were so many bodies on the island that it became a public health issue. And they tried taking the bodies out to sea, but they just washed back up on the shore. So, funeral pyres burned on Galveston Island for weeks and weeks. That devastating event gave rise to one of the largest flood risk management engineering projects in the US, called the Galveston Seawall. Today, the seawall is over 10 miles long, nearly 17 feet tall, and about 15 feet wide at its base.

The kicker of this story is that in the years leading up to 1900, the natural dunes on Galveston Island were purposefully removed for two reasons. One was that the sand in those dunes was mined to fill low lying areas so people could build more. The other reason is that tourists coming to the island to go to the beach found walking over the dunes to be a nuisance.

What a difference 120 years makes. Today, our colleagues with the Galveston District are working to develop and integrate beach and dune projects with the seawall to deliver more resilience into the future. These projects will actually extend the functional lifespan of that seawall and to make it more resilient with respect to future storms.

There’s a great book about that particular hurricane called Isaacs’ Storm (by Erik Larson, Vintage, 2000)

Tell us about the Network for Engineering With Nature, the USACE’s new partnership with the University of Georgia. What kinds of tools and materials can we look forward to seeing as outcomes?

We’re very excited about the Network for Engineering With Nature that we official launched this fall.  My colleague Dr. Brian Bledsoe at UGA  and I have done a recent podcast as well as a webinar about the N-EWN, for those who would be interested in learning more.  The intention behind N-EWN is to provide a “place” or a ”community” where organizations can share information, collaborate and work together to advance EWN practice.  USACE and UGA started N-EWN with resources provided by Congress in 2020.  Our hope is that we will be able to sustain the effort by drawing together such public support and combining it with private investment to advance natural infrastructure.  We’ve begun a range of both research and educational initiatives and would invite anyone interested in learning more to visit our N-EWN website and to contact us with their ideas.

Network for Engineering With Nature

Do you have any final words of advice to share with Leaf Litter readers?

People can contact to us through the Engineering With Nature website, to learn more or share their own ideas about how to move forward. The future is very bright for this approach. The challenges we have around infrastructure are shared by many other countries. We have the opportunity to create much more value through infrastructure investment by incorporating natural systems, but this requires innovation. It’s very important to find ways to positively pursue these opportunities, and not get bogged down in old, 20th century ways of approaching these challenges in the 21st century.

Whether you’re an engineer, environmental scientist, or conservation scientist, everybody has got to innovate. Sometimes it’s a bit too easy to point the finger at another discipline and say, “they are the ones that are holding us up.” That’s a counterproductive human tendency when it comes to making progress here. Every discipline needs to reflect on how it should be evolving and innovating to support these kinds of solutions.

[For a closer look at the progress of Engineering With Nature, check out this just-released 10th anniversary video and visit the EWN video page for more!]

People who are wired to say no to everything are a dime a dozen. You’ve got to find the people who know how to get to yes, if you want to change something.

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