Credits: Lathan Goumas, Virginia Sea Grant.
Andre de Souza de Lima $^1$; Tyler Miesse $^1$; Daniel Cardona $^1$; Celso Ferreira $^1$; Ali Shahabi $^2$; Navid Tahvildari $^2$
$^1$ Department of Civil, Environmental and Infrastructure Engineering, George Mason University, Fairfax, VA
$^2$ Department of Civil and Environmental Engineering, Old Dominion University, Norfolk, VA
Credits: Lathan Goumas, Virginia Sea Grant.
Global climate change has led to many adverse impacts including changing weather patterns and an increase in the severity and frequency of extreme weather events. Traditional hard engineering solutions for coastal protection, such as seawalls and bulkheads, are becoming inadequate as they do not have the capacity to keep pace with the accelerating impacts of climate change. In response, there is growing interest in Natural and Nature-Based Features (NNBF), which offer innovative and adaptive approaches to coastal protection. NNBFs, such as salt marshes or living shorelines, have demonstrated potential for mitigating wave energy, reducing flood risks, and enhancing coastal resilience. However, the effectiveness of these features can vary based on their physical attributes and the specific environmental conditions in which they are implemented. The inconsistent performance of NNBFs has posed challenges for their widespread adoption, partly due to uncertainties in their efficacy and barriers in public policy.
This research focuses on evaluating the performance of NNBFs in attenuating waves through the natural environment. Here we aim to deepen our understanding of how these features can contribute to enhancing coastal resilience.
The Captain Sinclair's Recreational Area (CRSA) is situated on the Severn River in Gloucester County, Virginia and is overseen by the Middle Peninsula Chesapeake Bay Public Access Authority (MPCBPAA). This area has been the focus of numerous shoreline protection initiatives designed to mitigate the impacts of erosion, a persistent issue as a result of the marsh's exposure to storm surge and waves.
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Notable storm events, such as Hurricane Irene, have underscored the exposure of the site to extreme events.
Impacts of Hurricane Irene within Mobjack Bay, Virginia (left) and at the MPCBPAA (right). In both figures, the pink dot highlights the location of the CRSA project site.
Credits: Flood Hazards Research Lab Archives, 2024
In response to these challenges, various NNBFs have been implemented to enhance shoreline resilience. These features include oyster sill bags filled with locally sourced shells from the Chesapeake Bay, rock sills, and naturally occurring salt marshes. Together, these approaches aim to stabilize the shoreline while supporting habitat restoration and wave energy attenuation.
Transects 1 and 2 highlighting the oyster sill bags and marsh (left and center); Transects 3 and 4 highlighting the rock sills and marsh (right).
Credits: Flood Hazards Research Lab Archives, 2023
Due to the site's exposed condition, we aimed to quantify the performance of existing NNBFs in attenuating waves. To achieve this, we deployed RBR Solo-D wave loggers along four transects over a year-long monitoring period. Sensors were strategically positioned before and after each type of NNBF within the transects, allowing for detailed analysis of their individual and collective impacts on wave attenuation.
A map of the four transects is presented below.
sensors_marsh
Clicking on the sensor points reveals a table with details including the sensor name and ID, deployment date, location relative to the NNBFs, and data availability.
The time series below shows siginificant wave height (Hs) over the one-year study period. The data is organized based on the sensors' transect and location relative to NNBFs.
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