Modeling Dune Growth and Recovery on Developed Barrier Islands
Abstract
Foredunes on developed barrier islands serve as the first line of defense from flooding during storms. However, management initiatives that seek to prevent overwash from occurring may inhibit the rollover process, which allows barrier islands to maintain subaerial exposure under sea level rise (SLR). Understanding how dunes and beaches will evolve over time as a function of the combination of SLR and management initiatives (i.e., sand fencing and beach nourishment) is critical to predicting whether or not barrier islands will be able to remain subaerial into the future. We hypothesize that managed islands will experience greater dune growth and erosion in the short-term but will drown sooner than unmanaged islands under the same environmental forcing conditions. To test this hypothesis, we use the recently developed coupled model framework, Windsurf, to simulate morphologic change on Bogue Banks, NC (BB), which serves as a case study location. Windsurf couples a nearshore model (XBeach), a dune model (Coastal Dune Model, CDM), and a multi-fraction aeolian transport model (Aeolis) to simulate geomorphic change across the profile from the nearshore to the dune. We calibrated the model for use on BB by performing a hindcast on two field profiles (one fenced and one non-fenced) from the island sampled between 2016-2017. From this, we find that the incorporation of management structures into the model framework allows for improved accuracy in simulating morphologic change along the managed portions of BB. We then use the calibrated model to perform a suite of 10-year forecast simulations using projected local SLR of 0.5m, 1m, and 2m by 2100. Including the effects of beach nourishment and sand fencing in these simulations demonstrates the role that management will play on the multi-decadal scale.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMEP064..04I
- Keywords:
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- 1625 Geomorphology and weathering;
- GLOBAL CHANGE;
- 3020 Littoral processes;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 4217 Coastal processes;
- OCEANOGRAPHY: GENERAL