Rapid evolution of shoreline after a beach nourishment downdrift of a groin and at an embayed beach: theory vs. observation

This paper describes the evolving shoreline over a 3,5 years period after an important nourishment, approx. 100 m3/m, made by submarine sand carried out in Lido di Dante beach, Italy. The focus is made on the evolution of an embayed beach of Lido di Dante and of the rapid evolution of the shoreline located down drift a groin. Different behaviors were observed downdrift the groin and in the embayed beach: in the unprotected zone, downdrift the groin system, a seasonal variation is evident. The shoreline retreated very fast after the nourishment and the evolution has been modeled by the classic Pelnard Considere equation. At the embayed beach no evident seasonal variation was observed. Main changes are due to beach rotation, dependent on the wave direction.