Exploring alongshore-coupled barrier island evolution: How does overwash affect developed and undeveloped barrier evolution and stability?
Abstract
Barrier islands are dynamic and ephemeral coastal features facing uncertain risk with climate change. Human development on barrier islands not only compels studies of future evolution, this infrastructure itself can affect the sediment transport processes that can keep barriers intact as sea levels rise. To understand how barrier overwash responses are translated alongshore, we couple a simple, morphodynamic cross-shore barrier island evolution model (the LTA model) in the alongshore direction. Beginning with a stable barrier island with a narrow barrier middle section, rapid overwash along the narrow portion of the model barrier sets up gradients in alongshore sediment transport that subsequently attempt to straighten the shoreline while translating increased rates of overwash alongshore. Comparing cross-shore (overwash) fluxes with local and regional alongshore transport gradients provides us with a novel quantitative tool to evaluate the length scales of long-term barrier stability. Next, human development is represented by decreasing the overwash flux on portions of the barrier, locally slowing the barrier response to sea-level rise. This local change in overwash flux can decrease the gradients in alongshore sediment transport of the entire barrier island. We explore how alongshore connectivity, a function of wave height and the spread of incoming wave angles, affects the evolution of barriers with varied levels of human development alongshore, comparing results to natural examples along the New Jersey and Massachusetts coasts.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMEP12A..03P
- Keywords:
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- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCESDE: 1625 Geomorphology and weathering;
- GLOBAL CHANGEDE: 1641 Sea level change;
- GLOBAL CHANGEDE: 3020 Littoral processes;
- MARINE GEOLOGY AND GEOPHYSICS