Modeling Barrier Island Evolution, Shoreface Morphology, and Overwash

Science Center Objects

Barrier island field observations provide information about past and current environmental conditions and changes over time; however, they can’t tell us about the future. Models can predict possible future behaviors but are only as good as their input data. By integrating both observations and models, we can extend observations and arrive at more realistic predictions of barrier island behavior and vulnerability to storms and sea-level rise.

There are several models and tools that we use to analyze barrier island change. For example, reduced-complexity models (RCM) are important tools for exploring the behavior of coastal barrier systems at decadal to centennial scales (10s to 100s of years). They focus on broad elements of barrier system geomorphology rather than capturing every component. Through isolation of individual processes, RCM can help illuminate the importance and magnitude of different forces on system evolution, such as rate of sea-level rise, increases or decreases in sediment availability, as well as direct landscape interventions by humans. Due to their relative simplicity, RCM are useful not only for contrasting the effects of different forces, but also for pairing with other models and field data to form comprehensive and transdisciplinary approaches to understanding coastal evolution.

 

When paired with remote sensing observations and geologic field data, RCM can be used to infer the sensitivity of real-world systems to past changes in environmental forces. This helps us reconstruct the history of coastal systems and determine the best parameters for forward modeling scenarios—predicting future change. We use a coupled field-model approach to explore interactions between the shelf, shoreface, beach, dune, and back-barrier, allowing us to investigate whole-barrier dynamics that are often overlooked by research focusing solely on each of these different domains. This can ultimately assist managers and stakeholders in understanding long-term changes in coastal landscape evolution driven by the interconnectivity of these domains under different environmental forcing scenarios.

 

Animated time lapse of extensive island change between the years of 1930 and 2019.

Aerial photos record 89 years of landscape change at the Little Beach barrier island in Atlantic County, New Jersey. The island, part of the Edwin B. Forsythe National Wildlife Refuge, is one of the only stretches of wild coast remaining in the northern Mid-Atlantic region. It is continually reshaped by the interplay of hydrodynamic processes, sand supply, and vegetation.

All of the images are published through the New Jersey Geographic Information Network (NJGIN) and Atlantic County Office of Geographic Information Systems, at: https://njgin.nj.gov/njgin/edata/imagery/index.html and https://www.atlantic-county.org/gis/.

(Credit: Meaghan Faletti, USGS. Public domain.)

Whole-barrier dynamics captured by reduced-complexity models include interactions between shoreline erosion, sediment storage in dunes, and overwash. These processes are demonstrated in a timelapse of landscape change at Edwin B. Forsythe National Wildlife Refuge in Atlantic County, New Jersey. The barrier here has been extensively reshaped by changes in sediment delivery and overwash since 1930.