Morphodynamic Evolution of Post-Nourishment Beach Scarps in Low-Energy and Micro-Tidal Environment

Abstract

Beach scarps are commonly associated with nourishment. Large and persistent beach scarps not only affect the performance of beach nourishment, but also are safety hazards to tourists. In this study, the morphological evolution of beach scarps was examined at a nourished beach in a low-energy and micro-tidal environment. Topographic surveys of nine beach profiles were carried out every 3–6 months after nourishment, lasting for nearly 4.5 years, combined with observed and simulated hydrodynamic data. The results showed that beach scarps were extensively developed after nourishment and migrated landward gradually. The formation of beach scarps was attributed to the higher designed berm, while the migration was possibly initiated by the subsequent higher total water level connected with the irregular tides. However, scarps were completely removed by the first post-nourishment severe storm and had been long absent ever since although two other energetic storms approached. This was different from the result of previous studies, which could be attributed to the much gentler upper beach slope. These results highlighted that the first post-nourishment storm played a key role in the evolution of beach scarps at low-energy and micro-tidal nourished beaches. This study also proposed two methods of determining berm elevation in beach nourishment according to China’s experiences, which would be helpful for other countries’ beach nourishment projects.

Evolution of the surface roughness of a coarse sand after a beach nourishment

“…To mitigate erosion processes, it is common to use artificial structures (breakwaters, groins, etc.) and to dump natural (dredged) or artificial (quarried) sand along the beach [7]. The incorporation of new sediments (different from the original ones) to beaches requires a thorough understanding of the processes to obtain the required response of the morphodynamic systems [1].…”

Evolution of Sediment Parameters after a Beach Nourishment

“…Beach nourishment is a common process conducted when the coastline is being subjected to erosion because of natural or anthropogenic causes, as it replaces sediments within a littoral system and allows natural forces to continue their operation [1,2]. This process involves the placement of large volumes of sand along the beach profile [3]. Nourishments are also often associated with exposed coasts with intensive levels of development or great recreational value [4].…”