Abstract
Situated along the western shore of Mobile Bay, the Dauphin Island Causeway serves as a key transportation corridor and the sole roadway to the “Sunset Capital of Alabama,” Dauphin Island. This strategically significant barrier island has 1,300 residents and is an important tourist destination. Shoreline erosion, loss of wetlands, rising sea levels, and coastal storms battering the shore have degraded the shoreline along this critical transportation link. The goal of the Dauphin Island Causeway Shoreline Restoration Project is to protect the existing shoreline from ongoing erosion and to restore habitat function to areas of eroded intertidal marsh. This project includes designing a 3.2-mile living shoreline to improve the resilience of the community by restoring shoreline along a key segment of the vulnerable roadway and creating a marsh habitat. The project will reestablish approximately 100-acres of tidal marsh and tidal creeks in Mobile Bay. Offshore breakwaters and sills will protect the marsh and reduce wave-induced erosion. The breakwaters will further serve as habitat for the challenged oyster population. Hydrodynamic modeling, sediment transport modeling, and a host of other tools are being used extensively in the planning process to determine the appropriate spatial arrangement, elevation, and composition of wave attenuation structures; appropriate marsh elevations; and depth, slope, and spatial arrangement of tidal channels. The wave attenuation structure design intends to reduce the erosional wave energy at the shoreline significantly. The marsh attributes intend to optimize tidal flooding dynamics in support of the proposed vegetation planting scheme and to maximize the benefit to marsh-dependent fishery species in the region. This presentation will discuss the design, challenges, and opportunities of this important shoreline project.
