Monitoring the effectiveness of re-establishing beaches artificially: methodological and practical insights into the use of video transects and SCUBA-operated coring devices

摘要

Artificially rebuilding beaches is one of the main methods used to stabilise or restore them after severe erosion events. Best practices should involve some form of monitoring prior to, during and post beach re-building. The most frequently applied monitoring techniques for Italian (and Mediterranean) beaches are topographic and bathymetric surveys carried out in regular time intervals in order to understand beach evolution. Morphological studies, based on grain-size profile analyses, can indicate the sedimentary evolution of the beach. In the present study, SCUBA diving techniques were employed in addition to traditional survey methods in order to monitor two study areas along the Ligurian coast (northwest Mediterranean Sea): Ospedaletti and Genova Vernazzola. In particular, a diver-operated, cost-effective coring system obtained marine sediment cores, and video transects and inspections generated information on the status of coastal defence structures (e.g. groynes). Using those methods, the main vertical discontinuities along the submarine beach were identified, as were points of erosion on the submarine parts of groynes. Such innovative techniques provided data that are not easily achievable with traditional monitoring techniques. Future monitoring programmes should consider these new methods as a way of improving assessment efficiency.