The race to save the South Atlantic coastline
From flooding and coastal erosion to the impacts of urbanization and increasing populations, the coastal zones of the South Atlantic are in crisis.
Without urgent action to build resilience, many communities could soon be “inundated” by the impacts of climate change, according to Dr Clay McCoy from the US Army Corps of Engineers (USACE).
McCoy, Technical Director of South Atlantic Division Regional Sediment Management (RSM) Regional Center of Expertise, is currently part of a team leading a four-year, $18.4 million, study that’s in the final stages of identifying risks and vulnerabilities to over 60,000 miles of South Atlantic coastline.
Working with multiple stakeholders, from academia to governments, coastal storm risk management strategies are being put forward to support and improve resilient communities and habitats along this vast stretch, which includes Puerto Rico and the US Virign Islands.
The study has already found that sea-level rise will “dramatically increase” the risk of coastal storm and flooding throughout the South Atlantic, with “significant vulnerability” in estuarine/riverine tidal areas. It’s also reported a “very high risk” for densely developed areas that have limited or no adaptive capacity.
One of the keys solutions favoured by stakeholders, according to McCoy, is creating more Natural and Nature-Based Features (NNBFs) such as wetlands, wooded areas, living shorelines, and beaches which can provide multiple benefits for a local community, including mitigating the impacts of storm surge and sea-level rise.
Flooding seen from the air as a US Customs and Border Protection, Air and Marine Operations, DHC-8 prepares to land in Aguadilla, Puerto Rico, September 22, 2017. US Customs and Border Protection photo by Kris Grogan.
While many of the world’s coastal zones are at extreme risk from the effects of climate change, the South Atlantic is particularly vulnerable.
“The region is full of beautiful coastal communities, beaches, barrier islands, expansive salt marshes, but it’s all quite flat.
“Much of the coastal zone is within about a metre or so of sea level, so we’re quite vulnerable. And because of our beautiful landscapes and nice climate with mild winters and warm ocean water, a lot of people are moving to the coastal zone in the southeast. It’s the fastest growing area in the country,” says McCoy.
Today, approximately 3 billion people live within 200 kilometres of a coastline. By 2025, that figure is likely to double. The high concentration of people in coastal regions has produced many economic benefits, including improved transportation links, industrial and urban development, revenue from tourism, and food production. But the combined effects of booming population growth and economic and technological development are threatening the ecosystems that provide these economic benefits.
Unless governments and users of coastal resources take action, population pressures and the associated levels of economic activity will further degrade many coastal habitats that are already under stress.
For the South Atlantic, these stressors are coupled with it being the number one hurricane destination, “which means we have our work cut out for us to reduce our risk and support those resilient coastal communities,” says McCoy.
Cities such as Miami, Tampa, and Charleston are at severe risk, but the region also has numerous small towns and communities dealing with the exact same risk of sea level rise and coastal storms.
And it’s not just the beachfront that’s being affected. “Now we’re seeing a greater focus on the estuarine and back way environments than you’ve seen in the past.
“If we don’t build these projects, and respond to climate change, I think a lot of these areas will be inundated. And then we won’t be able to use them. There will be immense economic damages, damages to infrastructure for example, and people,” says McCoy.
Louisiana’s coastline, for instance, is already disappearing at a rapid rate: Every 90 minutes, the state reportedly sheds another football field’s worth of land. But it’s not just land that’s been lost – the local population has also diminished. Between 2000 and 2010, parishes that were hit hardest by storms saw massive decreases in population—St. Bernard Parish, just east of New Orleans, lost 46% of its residents—leaving those who stay to make do with scarce job opportunities, neglected schools, and crumbling infrastructure.
New Orleans, LA-September 2, 2005- Neighborhoods throughout the area remain flooded as a result of Hurricane Katrina. Jocelyn Augustino/FEMA.
While funding remains an issue, it is increasingly becoming apparent to federal and state governments that resilience should take priority. The extreme weather events of the last few years have taken their toll on local and national economies – and with that has come a dawning realization that the cost of inaction far outweighs the cost of building resilience.
According to the National Oceanic and Atmospheric Administration (NOAA) the US has sustained 298 weather and climate disasters since 1980 where overall damages/costs reached or exceeded $1 billion. The total cost of these 298 events exceeds $1.975 trillion.
As of July 2021, there have been eight climate disaster events (two flooding, four severe storm events) with losses exceeding $1 billion. Overall, these events resulted in the deaths of 331 people and had significant economic effects on the areas impacted.
According to McCoy, the RSM strategies implemented across the South Atlantic have proved that money can be saved by taking preventative action. The RSM Center was established in 2015 and it’s first big project was a RSM Optimization Pilot, which involved analysing all its major coastal navigation and coastal storm risk management projects in the division.
“This demonstrated that by doing the beneficial use projects, which almost always includes a significant resiliency component, we were providing over $100 million in annual value across the southeast. And that results in being able to do more projects with less money,” says McCoy.
For instance, rather than dumping sediment dredged from Tampa Harbor offshore, the USACE has placed it on the beach near Egmont Key, a State Park, National Wildlife Refuge (NWR) and cultural and environmental resources centre.
“Doing the project at Egmont is the cheapest environmentally acceptable option for dredging and provides numerous benefits or value at no additional cost. If we didn’t do the project which costs the NWR and state nothing, it is likely Egmont Key would be much less resilient and would lose most of the environmental and cultural resources on the island,” according to McCoy.
A major part of the USACE’s work involves dredging, a process that involves excavating sediment or rock, primarily to maintain navigation channels for ports and waterways to provide safe, reliable, efficient and environmentally sustainable water-bourne transportation for commerce, national security, and recreation.
But the sediment can also be used to “build and maintain beaches and other beneficial uses such as bird islands, and thin layer placement on marshes,” says McCoy.
Placing sand in the nearshore at Folly Beach south of Charleston using a small hopper dredge. Image: USACE.
In the South Atlantic, the USACE is responsible for dredging tens of millions of cubic yards every year including nearly every major port in the southeast and over 6,000 miles of navigation channels. Project volumes can range from the tens of thousands of cubic yards to millions of cubic yards.
“Just getting a dredge to a site, what we call mobilization, costs around $2 million. But if we can dredge a navigation channel and place sand on the beach, by combining those two projects into one we’ve already saved money on a mobilization. If that beach would have had to pay for that sand from, say, an offshore source or something like that, it would have cost them about $15 a cubic yard. If you placed say 200,000 cubic yards, that’s another $3 million that’s been saved.”
But are enough funds available to build the resilience needed? “Not yet,” says McCoy, “but I think governments do understand that and we’re building the structure and capacity to take the steps we need to.
“We’re seeing some examples in state and federal governments, and even counties, that are adding resilience and climate change personnel to their staffs. It’s becoming an overarching theme and the coastal zone and states are even adding resiliency departments. Programmatically and structurally, we’re absolutely moving in that direction.”
For McCoy, the next step is deploying these projects at scale. “The foundation is built. We have a great base of knowledge and we’re working together; we’re learning from each other; we’re defining that vision for the future – and building it.”
“This is an all hands-on-deck approach, with partnerships and collaborations across our agencies, academia and the private sector to help us take those next steps. We must keep the issue of resilience to the forefront and continue to provide accurate scientific information to help policymakers make informed decisions at all levels.”