Coastal resilience in the Raritan River/Bay Region: projecting challenges and solutions for sea level rise

As sea levels continue to rise, low-lying municipalities will have to find innovative ways to reduce and eliminate risk to people, infrastructure, and critical facilities from flooding. Typically, coastal ecosystems such as coastal wetlands act as natural buffers and flood storage areas that protect coastlines from flooding and dampen storm surge. However, tidal wetlands are also being lost at record rates globally, threatened by development, erosion, and not being able to keep pace with sea level rise. Under natural conditions, tidal wetlands are able to migrate inland to keep pace with a rising sea level, but this gradual movement is impeded by anthropogenic development in coastal areas, such as roads, buildings, and infrastructure. Tidal marshes can also keep pace with a rising sea level through vertical accretion, or the gaining of elevation from settling of organic and inorganic material on the surface of the marsh, however, rates of accretion are not well known and vary across locations. In Chapter 2, four tidal marshes (two Phragmites australis and two Spartina alterniflora dominant) across the Lower Raritan River were selected to measure accretion using sediment plates over the span of 18 months. Data collected over the study period suggests that there is a negative trend in vertical accretion across all study sites, regardless of vegetation type. Average monthly rates of accretion for all S. alterniflora marsh plots were -0.07 mm per month and P. australis marsh plots averaged a rate of -0.24 mm per month over the study period. However, it is worth noting that additional studies are needed to establish benchmarks and long-term data needed to make local and regional planning decisions. In Chapter 3, a model that integrates environmental and socio-economic vulnerabilities prioritizes communities and locations for potential conservation and preservation projects. Models were created for four scenarios of sea level rise; 0.7 ft, 0.9ft, 1.3ft, and 3.3ft. For each scenario, a ranking of community vulnerability based on environmental, socio-economic, and combined vulnerability was generated. This list can be used by individual municipalities and counties to determine risk reduction planning efforts in the near future as communities are identified by census tracts. In addition, study results suggested that communities without coastal marshes were more vulnerable than communities with coastal marshes from a socio-economic perspective. Chapter 4 presents a preliminary prioritization of vulnerable communities within the study area, based on environmental and socio-economic vulnerability. Two communities were selected based on predetermined criteria Findings in this study identify the impacts in community composition, financial losses to the municipality from flooding, and an opportunity for the creation of nature and natural-based defenses to permanently eliminate risk to areas of the community while reducing flooding impacts to neighboring areas and providing increased ecological benefits. Finally, Chapter 5 provides an overview of key findings from each chapter, additional discussion on approaching and financing local and regional resilience. In addition, a discussion on limitations, challenges, and future directions is provided.Ph.D.Includes bibliographical reference