A simple model to estimate the impact of sea-level rise on platform beaches

•A model to estimate the impact of sea-level rise on platform beaches is proposed.•Approach is based on an equilibrium profile and beach sand conservation.•Application to Cascais (Portugal) suggests a significant reduction in beach width.

Estimates of future beach evolution in response to sea-level rise are needed to assess coastal vulnerability. A research gap is identified in providing adequate predictive methods to use for platform beaches. This work describes a simple model to evaluate the effects of sea-level rise on platform beaches that relies on the conservation of beach sand volume and assumes an invariant beach profile shape. In closed systems, when compared with the Inundation Model, results show larger retreats; the differences are higher for beaches with wide berms and when the shore platform develops at shallow depths. The application of the proposed model to Cascais (Portugal) beaches, using 21st century sea-level rise scenarios, shows that there will be a significant reduction in beach width.