2018 CSDMS meeting-057
Log in (or create account for non-CSDMS members)
Forgot username? Search or email:CSDMSweb@colorado.edu
Browse abstracts
Long Term Risks: Novel Barrier Island Retreat Behaviors Arising from Increasing Rates of Sea Level Rise
Knowledge of the hazards related to rising sea level on retreating barrier island systems has little historic precedent, and consequently, requires exploration of the sedimentological record to determine how these systems might respond over longer timescales. Fortunately, continental shelves around the world preserve records of former barriers as relict deposits, providing a window into past behaviors. The origins of these deposits are usually attributed purely to allogenic processes, or external environmental forcing, with many likely formed during episodes of increased rate of sea level rise. However, using a cross-shore morphodynamic model, we show that the internal dynamics of migrating barriers can also result in autogenic deposition of relict sediments even under a constant rate of sea level rise. Consequently, we propose that allogenic forcing from sea level rise and autogenic forcing from internal dynamics might interact to produce novel barrier retreat behaviors, with the potential to be recorded on the seabed by relict deposits. We model barriers through a range of interaction scenarios, showing that the morphology of deposits might be used to infer the relative influence of autogenic and allogenic forcing. Intriguingly, our results demonstrate that the internal dynamics of barriers can both amplify and dampen losses of shoreface sediment to the seabed during increased rates of rise, in some cases increasing the risk of barrier destruction. Future classification of relict deposits in the field could help explain if and when these behaviors arise, revealing long term hazards to modern barrier systems that have not previously been described.
