Long Wharf Flood Protection Study and Living Shoreline Design

Challenge

The Long Wharf area of New Haven, located within FEMA VE and AE high risk flood hazard zones, is highly vulnerable to coastal flooding. It has historically experienced severe flooding and flood damage from hurricanes and extreme weather events dating to the Hurricane of 1938 and more recently during Hurricane Irene and Superstorm Sandy. Improved resilience to coastal flooding is imperative to the social, economic and ecological resilience of the City of New Haven and the region.

Solution

GZA implemented a flood protection study in the Long Wharf District of New Haven. The District consists of two distinct areas in their character and use: the waterfront shoreline and the industrial district. The Long Wharf Flood Protection Study included planning and design of coastal flooding mitigation and shoreline protection measures for the area located northwest of the Long Wharf shoreline to Union Avenue. An inter-disciplinary team led by GZA completed a detailed flood vulnerability analysis in the project area. Based on the results of the vulnerability analysis, the team identified flood control strategies that not only addressed economic concerns related to business disruption after flooding but also identified ways in which the flood mitigation alternatives benefit the general public by creating a visionary plan for the City to improve social, economic, and ecological resilience to sea level rise, local intense precipitation, storm surge, and erosion. GZA’s project team includes Utile, Biohabitats, and Cambridge Systematics.

GZA’s project approach was multidisciplinary, and the team:

• Incorporated industry-accepted science for sea level rise and coastal flooding;
• Performed statistical analysis on historical storm surge flood level data from relevant water level stations, such as those from National Oceanic and Atmospheric Administration (NOAA);
• Used high resolution terrain data (post-Sandy);
• Completed high resolution, hydrodynamic computer flood modeling to characterize coastal flooding and its effect on structures and natural features;
• Created scenario-based flood maps to evaluate the vulnerability of the area to tides and storm surges;
• Managed all information using Esri ArcGIS geographic information system (GIS) software;
• Used a “risk-based” approach, defining coastal flood hazards in terms of probability, consistent with methods currently being used by state and federal agencies; and
• Identified resiliency strategies and alternatives that are consistent with City of New Haven’s current vision and plans for development.

The design includes an integrated approach to flood protection, shore protection, and environmental and ecological benefits, including a seawall, a buried revetment, timber walkway, beach nourishment and wetland enhancement, tidal flats, and oyster reef submerged breakwaters. This plan also creates a new level of access and usability of the shoreline by the public.

Benefit

The study identified strategies relevant to the character of the neighborhoods and areas to reduce coastal flooding in the district. It is also used as a road map for the City for creating social, economic, and ecological resilience in relation to future sea level rise impacts, storm surge, and erosion.

GZA’s permit-level design for the proposed Long Wharf Flood and Shoreline Protection project enables the City of New Haven to move forward quickly with final design and construction as funding is secured. The comprehensive analysis and design acknowledges that a resilient New Haven is critical to Connecticut and creates the resiliency features necessary to foster social, economic, and ecological health of the area.