24 Jan 2023

Swan Island Resilience Model Development; Phase I: Conceptual Model

Abstract: This report documents the development of an integrated hydrodynamic and ecological model to test assumptions about island resilience. Swan Island, a 25-acre island in Chesapeake Bay, Maryland, was used as a case study. An interagency, interdisciplinary team of scientists and engineers came together in a series of workshops to develop a simplified resilience model to examine the ability of islands to reduce waves and erosion and the impacts to nearby habitats and shorelines. This report describes the model development process and the results from this first key step: model conceptualization. The final conceptual model identifies four main components: vegetative biomass, island elevation, waves/currents, and sediment supply. These components interact to form and support specific habitat types occurring on the island: coastal dunes, high marsh, low marsh, and submerged aquatic vegetation. The pre-and post-construction field data, coupled with hydrodynamic ecological models, will provide predictive capabilities of island resilience and evaluations of accrued benefits for future island creation and restoration projects. The process and methods described can be applied to island projects in a variety of regions and geographic scales.

12 Aug 2022

Swan Island: Monitoring and Adaptive Management Plan

Abstract: Swan Island is a 10.12 ha island located in the Maryland waters of the Chesapeake Bay. Because of its value as a natural wave break for the town of Ewell on nearby Smith Island, as well as the ongoing erosion and subsidence of the island, in 2019 US Army Corps of Engineers (USACE)–Baltimore District placed 45,873 m³ of dredged sediment and planted 200,000 marsh plants. This restoration provided an opportunity to quantify the engineering (that is, resilience) and ecological performance of the island, postplacement. The lack of quantitative data on the performance of natural features such as islands has led to perceived uncertainties that are often cited as barriers to implementation. To address these data gaps, a multidisciplinary collaboration of five government entities identified project objectives and monitoring parameters through a series of mediated workshops and then developed a conceptual model to articulate those parameters and the linkages between them. This monitoring and adaptive management plan (MAMP) documents those monitoring parameters and procedures and can serve as an example for other scales, regions, and research questions. Documenting research and monitoring efforts may help to foster widespread acceptance of nature-based solutions such as islands.