Securing our shores

Naval Station Norfolk, the largest naval complex in the world, sits at the confluence of the James River and the Chesapeake Bay, just a few miles west of the Atlantic Ocean, in the southeast corner of Virginia.

Norfolk’s fleet of 75 ships and 134 aircraft discourages attacks on the station, but all that firepower does not deter, and never will deter, one particular foe: Mother Nature.

Mother Nature is winning her battle against Norfolk and every other coastal military base in the world. Storms and erosion are damaging these facilities—day after day, month after month, and year after year. Rising sea levels also threaten to submerge the base and are projected to reach seven feet in the area around Norfolk by the end of the century, according to a 2016 report by the Union of Concerned Scientists. As a result, a Category 4 storm (the second-highest hurricane classification category) could expose 95 percent of the base to flooding more than 10 feet deep.

The report wraps up by noting that the Navy is responding to these future threats by raising or restoring its piers, but the authors also write that the Navy will need “a more-detailed analysis” of these threats before it can take additional action.

“Our defense leadership has a special responsibility,” the report concludes, “to protect the sites that hundreds of thousands of Americans depend on for their livelihoods and millions depend on for national security.”

A more-detailed analysis

Nearly 1,700 miles from Norfolk, physicist Donatella Pasqualini sits at her desk in the Information Systems and Modeling group of Los Alamos National Laboratory. Her office is remote, perched on a mesa top, and surrounded by towering ponderosa pine trees. In that high-desert New Mexico environment, storm surge and sea-level rise aren’t problems that impact Pasqualini personally, yet she has built a career studying these things.

Pasqualini’s latest research focuses on the co-evolution of the natural world and the man-made world, especially on how infrastructure such as electrical power grids and substations interact with weather in coastal zones. “We want to project future evolution of the coastal zones and then quantify the risk that this evolution poses to infrastructure,” she explains. “And we want to plan for resilience.”

"We want to project future evolution of the coastal zones."
—Donatella Pasqualini

In other words, she’s working on the more-detailed analysis the Union of Concerned Scientists pointed to in 2016, one that will help us peer into the future and understand how erosion, storms, and rising sea levels will impact the infrastructure—including military bases—along our nation’s coasts.

Pasqualini and her team have developed a computer model they’ve named New Science for Multisector Adaptation. NeSMA, as it’s called, uses complex algorithms to process data about the physical characteristics of coastlines—including soil, vegetation, sensitivity to erosion—and how those characteristics would interact with a hurricane and its water swell.

NeSMA is much more complicated, and much more accurate, than the current method of using past weather events to predict future weather events. “The utilities and the government currently take a very simple approach,” Pasqualini explains. “They say, ‘OK, Superstorm Sandy came, and my electrical power substation was flooded. I’m going to lift up the substation to prevent it from being flooded in the future.’” But what they don’t account for is that—because of things like erosion and sealevel rise—the coastline is always changing.

For example, the major utility in the Delaware Bay area, PSE&G, spent billions after Sandy to shore up electrical substations flooded by the storm’s water surge. But Pasqualini’s model predicts that in the future, some substations the company raised wouldn’t have been impacted the same way, meaning PSE&G might have wasted money.

“So maybe the substation that Sandy flooded will not be flooded the next time,” Pasqualini says. “Maybe a facility somewhere else on the changed coastline will have a higher probability of flooding. Companies don’t always account for that possibility, even though they are investing billions of dollars.”

It’s not that the utilities and the government aren’t aware that coastlines will change. In fact, “they are very, very aware,” Pasqualini says. “The problem is that the changes are extremely difficult to model, computationally.” This is because the processes that cause coastlines to evolve are interrelated, affecting each other. For example, erosion affects a coastline’s vegetation (no soil equals no plants). But vegetation also affects erosion (certain plants might curb erosion or even cause soil to pile up). Throw in additional variables such as sea-level rise, storm surge, and flooding, and the relationship between erosion and vegetation becomes even more complicated. “Feedback—this interrelatedness— makes the problem more complex,” Pasqualini says. “It introduces some nonlinearity, in which cause and effect are not straight forward. Nonlinear problems are very difficult to solve computationally.”

But difficult computations are what Los Alamos scientists do best, and Pasqualini is no exception. First, she has to assign numerical values to everything she wants to compute. So, thank goodness for grad students. Around the Delaware Bay, one of Pasqualini’s focus areas, grad students have been busy testing soil composition for how well or poorly the soils drain water. They have mapped local vegetation and its density and have run experiments on how well the roots hold soil. After testing the soils, the grad students assigned numerical values to the many drainage qualities. These numerical values are then plugged into NeSMA.

Now, say a hurricane is headed toward the Delaware Bay. Pasqualini would download details of the hurricane’s wind speed and rate of travel, getting those numbers from the National Hurricane Center. When she plugged that data into NeSMA, the data would virtually collide with the coastal number set, and what came out on the other end of the computation would be the vulnerability of the Delaware Bay’s critical infrastructure. NeSMA shows the results on a map, with different colors indicating different levels of damage to an area. “For each model, you get approximations of the storm’s impact as seen in water table salinity, storm surge, and erosion,” says Pasqualini, noting that these computations are done on a supercomputer.

But NeSMA doesn’t just model current storms—it also helps predict the future.

Estimating the damage

Extreme storms have the most potential for damaging coastlines and infrastructure. In 2005, Hurricane Katrina inflicted an estimated $125 billion in property damage along the Gulf Coast. In 2012, Hurricane Sandy wreaked havoc on the entire Eastern Seaboard of the United States, causing more than $65 billion in damages. In 2017, Hurricane Maria swirled through the Caribbean, leaving more than $91 billion in total losses in its wake.

These extreme storms are becoming more common, of that Pasqualini is certain. But what she doesn’t know is how many storms will happen each year and how intense they will be.

“No scientist will say, ‘You will have 10 Katrinas in the next 10 years.’ What they will tell you is that there’s a likelihood of 10 Katrinas in the next 10 years.”

Because Pasqualini is concerned about the impact of these storms on infrastructure, NeSMA uses a combination of 10,000 possible storms with predicted sea-level values to understand the future risk to our coastal utilities. According to Pasqualini, the model forecasts “every imaginable situation, which helps you understand the things you could do to best prepare.”

In addition to demonstrating coastal changes after a storm, NeSMA predicts how many people might be without power after a hurricane. It also shows which substations are likely to be flooded and whether salt water will probably seep into the water table, reducing the supply of drinking water.

The infrastructure piece of the puzzle is complicated because electrical substations and water treatment plants are not isolated. Each is part of a network, “a node” in Pasqualini’s terms, that interacts with the network’s other nodes. So, for example, if NeSMA predicts a high likelihood of a power substation being flooded, the government may decide to invest in doubling the output of another station nearby.

NeSMA can also help local governments ensure specific outcomes in the aftermath of big storms. For example, perhaps a city wants to ensure that 80 percent of its population has power in the event of a major storm. Or perhaps all hospitals or all of Wall Street needs to have power. Which substations are essential for making those things happen, and what can a city do in advance to make sure those substations can weather the storm? “You can actually explore all scenarios to see where you should invest in infrastructure to keep places safe,” she says. Currently, NeSMA is the only model able to not only predict weather’s impact on our infrastructure but also recommend solutions.

Military applications

Pasqualini’s long-term goal is to be able to assess future risks for any region, anywhere in the world. Although NeSMA is currently parametrized for the Delaware Bay area, the model is “physics-based, and the physics doesn’t change, so we can take the model and apply it to different areas,” Pasqualini explains. “We just need to change the parameters—the details about the coastline.” (To collect these details, you need a lot of grad students taking measurements.)

Which brings us back to Naval Station Norfolk— and every other coastal military base that is facing an uncertain future. “We can tell the Department of Defense—with a level of uncertainty—how the future will be for these bases,” Pasqualini says. “We can do a risk assessment that is scientifically based.”

That means Pasqualini can say with some certainty if, over the course of the next 10, 20, or 30 years, there will be ground below the base, a hurricane and its storm surge will inundate the base, or the base’s infrastructure will be impacted by salinity.

“The military needs to know what the impact would be on critical infrastructure so it can plan the best ways to invest in making a base’s water supply and electrical power more resistant to damage from hurricanes,” she says, noting that things like building sea walls, digging new wells, or even physically moving a base are options.

According to the Union of Concerned Scientists, a three-foot sea-level rise would threaten 128 coastal Department of Defense installations in the United States. For Norfolk, specifically, that means that portions of the station would be flooded with each high tide. 

“It’s time to respond to such warnings,” Pasqualini says. “As a national laboratory, it is our responsibility to use our scientific knowledge to help make our nation more resilient.” ★