A MASS CONSERVATION MODEL TO PREDICT THE BEHAVIOUR OF COASTAL SOFT- CLIFFS DRIVEN BY SEA LEVEL RISE OVER MULTI-CENTURY TIMESCALES

Soft rock cliffs are common coastal features made of erodible material, such as clay and glacial deposits. The erosion of soft-cliffed coasts threatens communities around the world, destroying homes and habitats. Here we present a numerical model suited for estimating the evolution of these coastal systems over centuries in response to sea level rise (SLR) alone. To achieve computational efficiency, we propose a simple conceptual model, based on a mass- conservation approach. In this model we have relaxed the conditions used by Wolinsky and Murray (2009) when solving the Exner equation for cliffed coastlines. In particular, the assumptions of constant SLR and simplified inland topography. In this work we remove these restrictions, and obtain a simple behavioural equation for soft-cliffed coasts for which an analytical solution exists. This allows study of the conditions for existence of an equilibrium rate and the dynamics of equilibrium approach.