Living on the edge

As 100-year storms increase in frequency and severity, how can humans exist in harmony with water?

Situated on more than 100 small islands, Venice, Italy, attracts upwards of 20 million tourists annually—many of whom embark on gondola rides on more than 175 canals that thread through the historic city.

But in this city renowned for its waterways, water has become a problem. A century ago, it had seven tides each year. Now, because of rising sea levels, that number is closer to 100, and in November 2019, one of those tides caused historic flooding that a local Italian governor described to a National Public Radio reporter as “apocalyptic devastation.”

Just a few months earlier, a United Nations report (which cited more than 7,000 research publications) projected that by 2050, more than a billion people will live in low-lying areas vulnerable to devastating storms.

As our world changes, engineers also must grapple with renewed threats from water—for example, encroaching on coastal communities or from storms unleashing devastating floods.

Perhaps the greatest hurdle for coastal engineers is one they can’t control: People like living near water, and that doesn’t appear to be changing anytime soon. Think of Dubai in the United Arab Emirates, which boasts the world’s largest man-made harbor and an artificial archipelago, or the Florida island city of Miami Beach.

“More than 40 percent of the U.S. population lives in a coastal county,” says Jack Cox, a coastal engineer, director of engineering for Edgewater Resources, and a professor of practice in civil and environmental engineering at UW‑Madison. “As populations increase, this density increases and people’s desire to be connected with the water, in some way, continues to grow. So, there’s automatically a pressure to maximize the value (which can mean many different things to many different people) of our shorelines.”

Knowing that people like to live near water, and will continue wanting to do so—even in the face of rising seas or, in regions like the Great Lakes, water depths that can swing from one extreme to another in a few short years—Cox says engineers must find ways to protect increasingly dense population centers from the very environment they desire.

Perspectives on how to do that, he says, have shifted over the last half century—from imposing seawalls to relying on “soft” defenses to now somewhere in between. Each extreme has come with its own costs. Seawalls can be expensive and aesthetically displeasing, as well as disruptive to their natural environments. Soft defenses, such as extending sand beaches, can get expensive over time, as they require relatively constant upkeep as water washes away the sand. That washed-away sand also can have unintended consequences as the water deposits it elsewhere.

Beginning the 1970s and extending into the 1990s, coastal engineers moved toward using a mix of hard and soft structures. Forest Park Beach, located on Lake Michigan in Illinois, is an example of such defenses.

“That was built in the late 1980s,” says Cox. “If you took a picture of it on that day and a picture of it today, it looks almost identical. It has not changed—and that’s a positive.”

Today, coastal engineers also are integrating human-designed soft structures to guide natural processes. The idea is working with nature, rather than against it.

“You introduce some sort of structure—it can be an underwater reef, a living breakwater, or any number of things—and place it so that the waves think the shoreline is different from what it is,” says Cox. “As a result, you can better direct where the sand goes. It’s all in the physics of understanding waves.”

In New York City, for example, the East Side Coastal Resiliency Project aims to raise the East City River Park and implement buried coastal defense measures to protect land from ocean. Through the project, which is expected to be completed in time for the 2023 hurricane season, the city aims to thwart 100-year storms and the anticipated rise in sea levels by 2050.

“They’ve done three or four parks that have wetlands and soft-type solutions as the primary defense,” says Fred Klancnik, a professor of practice in civil and environmental engineering at UW-Madison. “It takes more land, but they do it in a way so that they’re engineering those protections, putting in hard structures and getting up to a higher elevation. Through sophisticated modeling and attention to detail, they’re coming up with solutions that will stand the test of time.”

Klancnik is an engineering veteran with nearly five decades of experience under his belt. The specific methods of engineering along shorelines have changed through the years, but he says the basics have remained steady since he graduated from UW-Madison in 1972.

In teaching the university’s future generations of engineers, Klancnik challenges them to understand the history of their sites and how much water levels can vary, especially on lakes.

Daniel Wright, an assistant professor of civil and environmental engineering at UW-Madison, looks at trends in worsening storms across the United States. In July 2019, he published a study that found extreme storms in the lower 48 states are dumping more rain, and doing it more frequently than 50 years ago.

These storms threaten not only coastal communities, but those along rivers and lakes, which are engorged with floodwater as harsh storms increasingly and rapidly fill them. While an obvious way for citizens, businesses or communities to avoid such floods is to avoid building in these vulnerable areas, for established communities near water, Wright says there’s a movement toward pulling the built environment away from riverbanks and adding green space as a buffer zone.

It’s a change from old ways of thinking about using flood walls, which could funnel floodwaters downstream and make flooding worse.

“In the old days, we often used to build right up to the edge of the river,” Wright says. “Now the idea is let’s turn it into a park, which has multiple benefits. You’re creating park land, which people like, but it also means there’s room, when a flood comes, for the water to go into that park land without damaging any buildings.”

Carolyn Voter, now a postdoctoral scholar at UW-Madison, focused on green infrastructure as a graduate student in civil and environmental engineering. In urban areas, which can be particularly vulnerable to flooding because they’re filled with impervious surfaces like streets, parking lots and sidewalks, there’s a growing focus on methods such as rain barrels, rain gardens and other water detention practices.

However, urban soils also tend to be compacted, and that leads them to behave more like impervious surfaces and shunt water elsewhere, rather than absorb it. “It is pretty popular for people to disconnect their downspouts and let them spill out into their yard, but if the yard soil has been compromised, it can’t absorb that water,” she says.

And while grassroots efforts contribute to the solution, Voter says it’s important for whole communities to adopt green infrastructure practices in order to make real changes. Many cities are still in the early stages, but some—Milwaukee, Philadelphia and Portland, Oregon, to name a few—are beginning to stand out as leaders.

“The power of the community is much stronger than what any individual person can do,” she says.

Coastal engineers must also look at how small adjustments alter the big picture. Cox says it’s crucial for communities to tackle these challenges together, from individual homeowners to governments, because nature works on a huge scale. For example, small walls here and there along a coast won’t solve the problem of encroaching water. In fact, depending on the design and circumstances, it might make things worse in other areas.

“Mother Nature doesn’t see an individual property,” he says. “It sees miles of shoreline, and things that happen are happening on the scale of thousands of feet, or even miles. The challenge isn’t just physically what you can do, but how you can do it on a broad enough level so that you actually can have a positive, meaningful impact.”