Author(s)

L. Rebaudengo Landò & S. Stura

Abstract

In this paper the evolution in time of free beach nourishment is dealt with by considering in a linked manner the processes of longshore diffusion of the filled sand and evolution of the cross profile, which presents an initial beach scarp that of steeper than that of equilibrium. After examining existing models relevant to the single processes, a simplified engineering model is proposed that follows the evolution in successive steps. Each step refers to the actual values of wave condition and profile slope that affect both processes. Application of the model to a realistic beach nourishment supplies an indication of the reduction in time of the surface of the sand platform between the initial boundaries, with particular reference to the first months after the filling works. Final considerations are made about the importance each process holds in the evolution. Keywords: beach fill, free nourishment, longshore diffusion, cross-shore profile evolution. 1 Introduction This paper takes into consideration the changes that a beach nourishment presents over time after a free beach fill is carried out to increase, for a designed extension, the width of the emerged beach, in order to defend existing coastal structures or to increase the space available as a seaside resort. Free fills, built with sand slightly coarser than the native one to improve the stability of the beach without altering its natural features, are appropriate when wave attacks are predominantly head on. Under this hypothesis the background transport rate has no influences, thus is not taken into consideration in the proposed model. In

Keywords

beach fill, free nourishment, longshore diffusion, cross-shore profileevolution