of Developed Coastal Barriers: Investigating the Threshold Rates of Sea-level
Rise for the Geologic-Human System
Andrew Ashton, Jeff Donnelly, Ilya Buynevich, Porter Hoagland, Hauke Kite-Powell, Di Jin.
Coastal barriers, often idealized by
the long chain of barrier islands found along the Atlantic and Gulf coasts of
the United States,
are most often found worldwide as spits or local expanses of beach, separated
from the mainland but anchored to cliffs, bluffs, or other geologic ‘hard’
structures. These sandy, wave-worked deposits contain a beach, a resource that
is particularly valued. Significant amounts of infrastructure are located on
barriers, including homes, resort complexes, hotels and roadways. Under natural
conditions of moderate sea-level rise, such as the U.S. has experienced during
the last few thousand years, barriers appear to have steadily migrated
landward, with processes of overwash and breaching transferring sediment onto
the backbarrier, allowing the barriers to keep up with rising sea level. Over
the next century, however, these barriers face an unknown future. Rates of
sea-level rise already exceed those experienced over the last several thousand
years, and are predicted to be substantially greater by the end of the century.
We propose research to address two key questions: 1) Are there threshold rates of sea-level rise beyond which barriers
will drown completely? and 2) Will
human responses to sea-level rise mitigate or exacerbate the potential for
barrier loss across entire systems?
This project, funded by the Dynamics of Coupled Natural Human Systems
program at NSF, is just getting underway. We have already held a
meeting with stakeholders and coastal planners at wch we discussed issues related to shoreline change and human intervention and mitigation strategies.