A PROCESS-BASED NUMERICAL MODEL OF SHOREFACE PROFILE EVOLUTION

Abstract

It remains a challenge to model numerically profile evolution across the shore-face from deep water to the shoreline with stability and accuracy. At long time scales, attempts to date typically utilise equilibrium profile shapes or bed slopes, with profile change based on the degree of disequilibrium and wave/current forcing, primarily for the surf zone in erosion events. Simulation of shoreward bar migration and beach recovery after erosion events is generally poor. Here we present an effective integrated framework and process-based dynamics in the form of a new software package that successfully models the whole shore-face zone seamlessly from relative deep water to the beach. It incorporates analytical procedures, including some simplified empirical relationships, that describe the forcing of waves and currents and the sedimentation responses that change the profile. It is shown to simulate profile evolution satisfactorily, with shoreward as well as seaward sand transport, bar development and migration and beach erosion and accretion, in a manner and at time-scales consistent with measured data, for both small scale laboratory and prototype modal and storm conditions. The model caters for water level variations due to tide, storm surge and/or sea level rise. It may be used to assess beach nourishment deposition at the beach berm, lower shore-face or across the surf zone.