• Characterization of coastal flood and erosion risks
• Living shoreline and habitat survey
• Site and bathymetric survey
• Metocean data analysis and 2D hydraulic modeling
• Mitigation alternatives
• Conceptual design
• Solution combined coastal engineering and ecological considerations with nature-based solutions provided through collaboration with Design with Nature Studio
Challenge
The Quonochontaug Pond Breachway, owned and maintained by the Rhode Island Department of Environmental Management (RIDEM), is highly vulnerable to coastal flooding and shoreline erosion, including loss of the existing tidal fringe marsh and deterioration of the existing stone revetment constructed in 1960s, jeopardizing use of the access road and boat launch facility during flood events. The entire study area is within the FEMA one-percent annual chance flood zone. Projected future sea level rise is expected to exacerbate the situation.
Solution
GZA performed a preliminary site assessment and concept design task, including characterization of the flood and erosion risk based on existing conditions under the current and future sea level scenarios, evaluation of mitigation alternatives, and development of a conceptual design.
GZA's coastal engineering and ecology specialists, in collaboration with the Design with Nature Studio, provided the following services.
- Detailed metocean data and flood risk analysis
- Site and bathymetric survey
- Existing vegetation and habitat survey
- Mitigating erosion design measures and improvements
- Restoration of the stone revetment to mitigate bank erosion
- Establishment and/ or improvement for marsh habitat
- Elevation of the access road for CRMC’s projected sea level rise in 2035
- Improvements to pedestrian access to the shoreline
- Improvement to parking conditions
Benefit
GZA's site assessment and conceptual design will provide a roadmap for the next project steps, including preliminary regulatory review, stakeholder outreach, and final design. GZA's study will also be used to support future federal and state grant applications. GZA is experienced in Living Shoreline design and GZA's proposed application of a Living Shoreline for this project site will both maintain and enhance essential habitats and mitigate shoreline erosion.