Climate-change impact assessment for inlet-interrupted coastlines

Climate-change (CC)-driven sea-level rise (SLR) will result in coastline retreat due to landward movement of the coastal profile (that is, the Bruun effect). Coastline change adjacent to commonly found tidal inlets will be influenced not only by the Bruun effect, but also by SLR-driven basin infilling and CC-driven variations in rainfall/runoff. However, as a model that accounts for all of the above-mentioned processes has been lacking so far, most coastal CC impact studies until now have considered only the Bruun effect. Here, we present a scale-aggregated model capable of providing rapid assessments of coastline change adjacent to small inlet-estuary/lagoon systems due to the combined effect of CC-driven SLR and variations in rainfall/runoff. Model applications to four representative systems show that the Bruun effect represents only 25-50% of total potential coastline change, and underline the significance of coastline change due to SLR-driven basin infilling and CC-driven variations in rainfall/runoff.