Along the South Shore of Long Island is a 150-acre town-owned area that is increasingly vulnerable to coastal flooding and precipitation events. It predominantly consists of open areas, wetlands and minor residential and commercial developments.
Home to nearly 13,000 residents, the project area is dominated by an economically challenged community that has also been experiencing a 20% housing unit vacancy rate.
Managed-retreat program allowing for wetland restoration
The local authority has implemented an innovative managed-retreat program to protect residents from future damage due to flooding. Another significant benefit of the managed-retreat program is that it allows for the restoration of currently degraded wetlands habitats.
The Town initiated this program in response to impacts to the area of Super Storm Sandy and more recent flooding associated the sea level rise and global climate change.
Using nature-based solutions to protect from climate change
The primary purpose of the project was to evaluate options and provide a conceptual design using innovative habitat restoration techniques and nature-based solutions (NBS) to protect the area from future impacts associated with meteorological events and climate change, such as hurricanes, Nor’easters and sea-level rise.
These new and evolving techniques will have many positive benefits, including providing protection to upland communities and restoration of anthropogenically-impacted wetlands habitats to native and healthy ecological conditions. Therefore, the Ramboll project team employed a nature-based approach to coastal resiliency.
Conceptual designs to restore and reconnect habitats
Ramboll has developed conceptual-level schematic design plans for the resilient restoration and hydrological reconnection of coastal wetland and upland habitat in the project area. The design allows for natural habitats to flourish while decreasing flood risk for the near-term future.
The conceptual design plan was informed by high-resolution, remote-sensing surveys, ecological field survey and botanical assessment, hydrologic investigation and 2D flood modeling, and the community’s desire for enhanced coastal resilience and safe access to the waterfront via public walkways.
One of the key tools utilized for this project was the development and use of a hydraulic model, which allowed the Project Team to evaluate various nature-based intervention measures rapidly – the model was fully-calibrated with known and confirmed site-specific parameters.
Nature-based designs to buffer and mitigate flooding
One of the main project outcomes was the proposed nature-based designs created for buffering and mitigating flooding (storm surge, sea level rise, rainfall) to better protect the area’s upland residential communities.
Another project outcome was that we were able to predict and design for the types of habitats which would result from the project interventions, both in the terms of habitat as well as their ability to dampen storm surge energy.
In addition to Town funds, the project was supported by a National Fish & Wildlife Foundation (NFWF) National Coastal Resilience Fund (NCRF) Grant.
Summary
Overall, this project serves as a catalytic and prototypical model for other developed coastal communities considering a managed retreat strategy or wanting to enhance coastal resilience while also using nature-based ecological techniques to mitigate coastal flooding and provide benefits to fish and wildlife habitat.