Research of Chesapeake Bay wetlands may provide natural solution for coastal protection
March 23, 2018 / by Martha Bushong
Juan Garzon, a PhD student in Civil Engineering, studies the effects of storm surges in the coastal wetlands of the Chesapeake Bay. He is a member of the team of researchers in the Flood Hazards Research Lab. (Photo courtesy of the Flood Hazards Research Lab).
Mason Engineering students measure the height and plant desity of spartina, a marsh grass that may help mitigate storm surges. (Photo courtesy of the Flood Hazards Research Lab).
Assistant professor Celso Ferreira (front) and PhD student Juan Garzon take measurements in the coastal wetlands near Cape Charles, Virginia. (Photo courtesy of the Flood Hazards Research Lab).
When PhD student Juan L. Garzon came to Mason from Spain, he fell in love with the marshes and wetlands of the Chesapeake Bay. “Many people think of the wetlands in a negative way as a place full of bad smells and mosquitoes,” says Garzon, “but coastal marshes, among many other things, have the potential to shield communities from storms.”
Hurricanes like Irma, Harvey, Maria, and Sandy remind us every summer how vulnerable we are. These storms can cause huge economic losses and fatalities in coastal communities, he says.
While traditional infrastructures, such as levees and dikes, have been used to protect populations living on the coast, a new approach might be needed because of the threat of the rising sea level and climate change, says Garzon. That is what lead him to begin searching for an environmental solution to coastal flooding.
Among the different alternatives for coastal protection, wetlands might be the most appropriate form of protection. These ecosystems present two huge advantages over traditional infrastructures. First, they can capture carbon dioxide from the atmosphere and transfer it to the ground, fighting climate change and global warming. Second, through a sedimentation process they can grow vertically, helping to maintain the coastal elevation when the sea level is rising.
Wetlands are the transition space between the sea and the land and they receive the direct impact of waves and flooding. The complex interaction between waves, currents, tides, and the vegetation growing in wetlands is far from being completely understood.
“My research aims to better understand the ability of wetlands in the Chesapeake Bay to reduce the height of ocean waves,” says Garzon.
Wetlands can be used as a natural defense against waves to protect coastal communities from the strong impact of waves. When wetlands flood during a coastal storm, waves can travel across land, he says. However, waves produce a force over the plants and it reduces wave energy and heights. Without the presence of the vegetation, waves will travel freely along the wetlands, hitting houses and buildings, overtopping coastal defenses, damaging properties and threatening people’s lives.
Garzon took field measurements during storm events and discovered that ocean waves are efficiently dissipated by the vegetation, and they disappear in less than 200 meters. He also developed a mathematical expression which can predict the wave height decrease inside the wetland for any storm and plant conditions. This expression can be used for coastal engineers when they are designing protection plans against coastal hazards.
“Juan was part of the team that created one of the largest datasets in the world documenting the interaction of hurricane storm surge and waves in natural coastal areas such as the marshes in the Chesapeake Bay,” says Celso Ferreira, assistant professor in the Sid and Reva Dewberry Department of Civil, Environmental, and Infrastructure Engineering.
“Juan is not only enhancing our current understanding of the capacity of these ecosystems to offer protection against flooding from storm surges and wave action but also providing predictive engineering models to support the adoption of nature-based features as a valuable coastal protection strategy against coastal storms.”
“The outcomes of my research promote wetland protection and restoration,” says Garzon. “This will help to fight against climate change and protect coastal populations and therefore reduce our vulnerability against hurricanes.”