The app enables users to explore 36 different future scenarios of coastline change along a generalized Virginia barrier island system. The scenarios are based on three coastal processes that act alone or in combination to create a shift to the coastline via erosion or accretion of sediment:

Relative sea-level rise: Occurs because of the the expansion of oceans due to warming temperatures, melting of land-based ice, and local rates of subsidence. Accelerated rates of sea-level rise can cause barrier islands to migrate toward the mainland, allowing them to maintain elevation as long as they can get enough sediment.

Shifts in wave climate (or the average distribution of wave characteristics over many years): This includes a number of factors relevant to sediment transport including the angle waves are approaching from and the height of the waves. If storm frequency of intensity changes because of climate change, the influence of waves approaching from different directions may also change, affecting how sediments shift and therefore how coastlines evolve.

Beach nourishment: This is a management strategy implemented to prevent erosion and beach loss in an effort to stabilize or protect shorelines. Beach nourishment was modeled only for those areas where it has been undertaken in the past (Wallops) or may be considered in the future (Assateague) based on stakeholder input, but the selected nourishment scenarios should in no way indicate an endorsement of any management option, either in those areas or elsewhere in the region.

In this app, you’ll be able to explore the modeled effect— alone or combined—of three relative sea-level rise projections, three potential wave climate scenarios, and four beach nourishment scenarios, on the rate of coastline change. The results will show you, along a generalized coastline, whether these scenarios will lead to more erosion and less accretion or less erosion and more accretion along the modeled future shoreline than would be expected to occur in the future under current conditions.

Because of the uncertainty in the environmental variables affecting coastline change, coastal geomorphologists cannot make detailed predictions of where barrier islands will be or what shape they will have in the future.

However, numerical modeling allows scientists to take an important step toward determining how certain physical processes may affect the future evolution of barrier islands and the coastline. Modeled future scenarios in the app of a simulated Virginia barrier island coastline are a leap forward in the field of coastal science.

However, at this early stage, the results are not yet intended to support decisions but to serve as a springboard for new and additional research and modeling efforts. Lessons learned from this breakthrough model will provide opportunities for next steps in modeling possible coastline and island evolution and advancing the science of coastal geomorphology.

The Coastline Change: Future Scenarios app was developed through a partnership between a team of coastal geologists and geomorphologists from University of North Carolina at Chapel Hill, University of North Carolina Wilmington, Duke University, and Randolph-Macon College (team that performed the modeling work) and staff from The Nature Conservancy, NASA-Wallops Flight Facility, the U.S. Fish and Wildlife Service Chincoteague National Wildlife Refuge and the Accomack-Northampton Planning District Commission.