Assessing Future Coastline Change in the Vicinity of Tidal Inlets via Reduced Complexity Modelling

Coastline change in the vicinity of tidal inlets is mainly influenced by four processes; the Bruun effect, sea level rise driven basin infilling, variations in river discharge and fluvial sedimentation, which are driven by both climate change and anthropogenic activities. However, a coastline change model that accounts for all of the aforementioned processes under both climate change and anthropogenic influences has been lacking. The methodology presented here accounts for climate change and anthropogenic forcing in assessing potential future coastline change in the vicinity of two different types of tidal inlets. Application of this method indicates a coastline progradation of ~20 m at Kalutara inlet (Sri Lanka) and a coastline recession of ~30 m at Alsea estuary (USA) by 2100. Scrutinizing the relative contributions to these predicted coastline changes illustrates that anthropogenic influences could dictate fluvial sediment supply to coasts, underlining the significance of integrating both climate change and anthropogenic influences when assessing future coastline change along inlet-interrupted coastlines.