Monitoring and evaluation of sand nourishments on an embayed beach exposed to frequent storms in eastern China
Abstract Beach nourishment is a proved effective protection approach which has been widely used in recent years. An Argus video monitoring system has been set up to monitor morphological changes and effects of continuous nourishments at Dongsha beach, an embayed beach in Zhoushan Archipelago, eastern China. Video-derived shorelines along with their morphological parameters, such as dry beach width, dry beach area, beach orientation and unit width volume were analyzed during the monitoring period from June 2016 to July 2017. Analysis of video monitoring data shows that shorelines retreated during autumn and winter when storms were intensive, while advanced in spring and summer, with a lot of bulges occurred after nourishment projects. Abrupt variations in the beach orientation were always followed by gradual recoveries to the average beach orientation, while continuous counter-clockwise rotation occurred after March 2017 when storm events were sparse. Comparing the different beach responses to individual storm events, we found that small-scale and short-interval sand nourishment implemented timely after storms can compensate for sediment loss more effectively on this beach. This study can provide a reference for local beach management.