As water levels rise in the Chesapeake Bay due in part to climate change, the region’s residents must fight the rapidly accelerating erosion of their coasts. Chesapeake Sea Level Rise and Storm Surge: Public Awareness and Response (CSSPAR), a project to which the National Geographic Society contributed, predicts the estuary’s waters could rise up to two feet by 2100.
In the past, hard structures like seawalls were constructed to protect the region’s beaches and shorelines. Now, a new set of strategies called “living shorelines” are being implemented to combat erosion.
“It’s basically a natural approach to shoreline management that incorporates elements of natural coastal processes,” says Zoë Johnson, the program manager for climate change policy at the Maryland Department of Natural Resources.
Hardened structures such as concrete seawalls attempt to hold back water and prevent erosion. However, these methods obstruct coastal beauty and provide less protection than natural wetlands, which absorb storm surges. In contrast, living shorelines are essentially reconstructed wetlands, designed to be an extension of the natural landscape of an area, including natural vegetation. This natural vegetation secures the soil, preventing erosion.
In 2008, Maryland passed the Living Shoreline Protection Act, which requires landowners who are protecting their property against erosion to adopt living shoreline methods.
“There are all sorts of different ways to do it, but you can put in a groin or a jetty or an offshore breakwater, something to dampen the wave exposure, and then you are preparing the land in a way that will replicate natural processes by strategic planting and rock placement,” Johnson says.
Extensive research by various government and nonprofit organizations found that past efforts to slow coastal erosion were negatively affecting coastlines.
“There’s a lot of literature on how much damage shoreline hardening has done in terms of losing your sediment supply,” Johnson says. “There’s a hard wall that would prevent wetlands or other coastal habitats from migrating inland. There’s this hard barrier that can do damage to other properties that are down the drift sector.”
Bhaskar Subramanian, the Maryland Department of Natural Resources’ manager of riparian and wetland restoration, is another coastal erosion specialist who thinks we must move away from the policies of the past.
“Earlier, people used really, really big rocks [to combat coastal erosion],” he says. “We are actually trying to move away from that. We don’t want to create the next Great Wall of China on our shorelines.”
According to Subramanian, native marsh grasses such as smooth cordgrass and salt marsh hay can be important components of living shorelines. Rocks and jetties placed in front of the grasses help secure the grassy wetland shoreline.
“What the rocks are doing is basically giving the plants that are planted behind them a chance to survive, because the bulk of the work is done by the plants,” he says.
Subramanian says that 2003’s Hurricane Isabel, which created an eight-foot storm surge in the Chesapeake Bay, proved that living shorelines could be more effective in protecting coastal regions than hardened structures.
“Four or five teams went out into the field and did some analysis, and basically everybody concurred that living shoreline projects survived the hurricane to a great extent as compared to bulkheads or ripraps or any other structures,” he says.
Adapting to Climate Change
Living shorelines do more than just slow coastal erosion. They also help sustain native plant and animal populations of the Chesapeake Bay. Fish, oysters, crabs, and wading birds are all familiar sights along living shorelines.
“What we are trying to do is to restore these marshes and make sure these critters have a home,” Subramanian says. “These living shoreline projects have proven in the past and are still proving to be efficient in creating really good habitats for these bay species.”
In Dorchester County, Maryland, a low-lying region that CSSPAR predicts could be inundated by rising bay waters, Subramanian says he discovered a particularly effective living shoreline project on private land. He asked the landowner how he cared for his living shoreline.
“Basically, what he said was he thinks his shoreline grasses are an extension of his garden,” Subramanian says. “Whenever there are plants involved, there is always some kind of maintenance that needs to be done. There are weeds coming in. There is wave action. You see huge chunks of big logs floating. When the tide goes out, [the logs] actually stay on the shoreline and smother the grasses.”
Subramanian believes that just a little care can allow a living shoreline to protect the coast for years.
“One of the biggest challenges for these marsh grasses is the lack of maintenance,” he says. “If it isn’t being maintained well and if there are too many invasive species, that could actually jeopardize the longevity of a project.”
If properly implemented, Subramanian believes living shorelines can be an effective tool as water levels rise due to climate change. “From my study, living shoreline projects can go a long way in reducing the amount of sediments that wash into the waters,” he says. “Of the 200 plus projects that I studied, the total amount of sediments prevented from going into the water is 49,877 tons per year. That, according to me, is a significant number.”