Dauphin Island, Alabama, is a strategically significant barrier island along the northern Gulf of Mexico and, more specifically, serves as the only barrier island providing protection to much of the state of Alabama’s coastal natural resources. The size of the system spans over 200 acres of barrier island habitat including beach, dune, overwash fans, intertidal wetlands, maritime forest, and freshwater ponds. In addition, Dauphin Island provides protection to approximately one-third of the Mississippi Sound and estuarine habitats including oyster reefs, marshes and seagrasses. The island has been severely impacted by repeated extreme events over the past several centuries, most recently Hurricanes Ivan, Katrina, and Isaac, and by the Deepwater Horizon oil spill. The State of Alabama, the USGS, and the USACE are conducting a joint study to evaluate feasibility level alternatives to increase resiliency and sustainability of Dauphin Island.
USGS TasksTask 1.1 Data Compilation.
Existing datasets will be compiled and cataloged.Task 1.2 Database Development.
Data formats will be leveraged, developed, standardized, and documented.Task 1.3 Tool Development for Analyses.
A web mapping application will be developed to visualize, spatially search, and disseminate the Dauphin Island data. Task 2.1 Bathymetric and Geophysical Surveys.
Bathymetric and stratigraphic characterization of Dauphin Island and surrounding waters will be conducted to evaluate the physical environment including surface elevations, morphology, habitat, and geologic framework. Task 2.4 Sediment Distribution.
Characterization of sediment texture, including detailed grain size metrics, within coastal-zone environments will be obtained in order to evaluate relationships among sediment-transport patterns, alongshore variability, geotechnical properties that influence the development of shoreline nourishment and restoration approaches, and for inclusion in models to help anticipated coastal-system response to storm events. Task 2.5 Water Quality.
Water quality and sediment data will be collected 8 times at four locations in the Mississippi Sound of Dauphin Island to update existing baseline conditions and provide needed data for modeling efforts. Task 3.1 Gulf Facing Shoreline.
An updated analysis of historical and present day Gulf facing shoreline positions will provide the basis for assessing short-term and long-term shoreline change along the coast. Analysis will include the combination of historical beach profile surveys and historical aerial photography conducted in previous studies as documented in Byrnes et al., 2010 and 2012. GIS shapefiles will be produced and available for volumetric change analysis.Task 3.2 Estuarine Shoreline and Environments.
The project will examine changes in back-barrier estuarine shoreline to derive trends in shoreline erosion/accretion, island width, and increases or decreases in vegetated communities. Task 3.3 Habitat Mapping.
High-resolution, aerial imagery, and a baseline habitat map will be developed to establish a baseline of the habitat extent within the study area.Task 5.1 Hydrodynamic and Morphological Change Modeling.
A numerical model of coastal processes will be developed for Dauphin Island using a coupled Delft3D and XBeach modeling approach. Task 5.4 Habitat Modeling.
Modeling and assessment of habitats and vegetative units for time-steps for long-term scenario analyses using contemporary relationships (i.e., elevation and landscape position) to produce habitat maps and acreages for geomorphologic scenarios. Task 6.2 Alternative Assessment Tool Development.
Results of modeling and expert opinion will quantify the consequences of each alternative relative to natural resource benefit, the likelihood of project success, and the impact to coastal protection, as well as other objectives that will be elicited from the appropriate stakeholders and decision-makers. Task 7 Monitoring and Adaptive Management.
A monitoring and adaptive management plan and a conceptual ecological model will be developed for the project. Task 9 Project Management and Coordination.