Research sponsored by the National Centers for Coastal Ocean Science demonstrates the importance of incorporating dynamic shoreline changes into models over time to forecast sea level change impacts.
Projected sea level change impacts are often depicted by assuming coastlines migrate unaltered over time with the rising or falling sea level. While valid for hard, rocky shorelines, this static or 'bathtub' concept is not applicable for dynamic, soft, sandy shorelines and coastal marshes, as they quickly erode or accrete new material.
New hydrodynamic modeling fromthe University of Central Florida project predicting impacts of sea level rise in the Northern Gulf of Mexico (Mobile Bay, AL to St. Andrew Bay, FL) uses a dynamic modeling approach to sea level rise depicting increased tidal ranges and tidal dispersions within the bay systems. Although the model predictsno fluctuations intidal ranges, changes in tidal deviations (prisms) in some bays occurs, depending on whether the horizontal profile of the bays increased or decreased with the projected erosion or accretion. Barrier islands with projected erosion are vulnerable to increased overtopping from storm surge inundation; this impels more water into the back-bays and increases inland flood plain inundation. Barrier islands projected to grow remain similar to present-day shorelines, preventing additional wave overtopping and limiting more water from entering the back-bays.
The results highlightthe significanceof depicting sea level rise as a dynamic process and incorporating shoreline changes into models evaluating the future response of the coastal system to sea level rise. This research, applicable to other coastal regions, is published in the journal Natural Hazards .