Barrier islands with narrow strips of sandy beaches protect mainland coasts and provide a sheltered environment such as a bay and lagoon behind them. During hurricane seasons, barrier islands absorb devastating energy of waves and currents, and shorelines suffer from severe erosion. Coastal inlets disconnect longshore sand transport, but have certain capability through waves and tidal currents to bypass sands from the updrift side to the downdrift. Sand bypassing is a complex sediment transport process, dependent on hydrodynamic forcing around inlet, evolution of ebb/flood deltas and nearshore bars, and anthropogenic activities (hard structure installation, sand mining, dredging material disposal, and beach nourishment). Quantification of long-term evolution of shorelines along barrier islands is a key task to assess the effectiveness of coastal protection measures over their decade-long lifecycles. Long-term and regional shoreline changes can be predicted by a one-line type of shoreline evolution model, with inclusion of empirical inlet reservoir model (IRM) for quantifying inlet bypassing efficacy through a sediment pathway to exchange sands between beaches and deltas. However, due to simplicity of the empirical IRM model, the model is unable to capture the effect of migration of deltas and bars on inlet sand bypassing, particularly during storm seasons with high wave energy. This study is to establish a multi-models approach by using an integrated coastal morphological model and a shoreline evolution model to simulate long-term shoreline variations around inlets. The morphological model is applied to investigate the trends of spatiotemporal variations of ebb-tide delta and bars. The morphological results will help develop a better IRM model for the shoreline evolution. Simulations of shoreline evolution using this multi-models approach are demonstrated to reproduce the decade-long shoreline changes around the Absecon Inlet, New Jersey.
