Analysis of bed level elevation during beach recovery after storm on Golden Beach, Hailing Island, Guangdong

The bed surface changes during the initial stage of beach recovery after a typhoon are an important research content for the mechanism of beach evolution. We analyzed the characteristics of the bed level elevation (BLE) change under various tidal cycles and wave conditions using the BLE and wave and tidal data of the surf zone of Golden Beach (Jinshatan, Hailing Island (Yangjiang, Guangdong, South China), which were obtained from field observation from August 17 to 22, 2021. We then used continuous wavelet transform to analyze the characteristics of the cycle change of the BLE. The findings are ① during the beach's storm-related recovery phase, the majority of the waves are breaking waves, and the beach recovers quickly at low tide when there are powerful waves, while the beach recovers to a limited extent at high tide coupled with weak waves. ② The BLE decreases during the "highest tide" and raises during the "sub-highest tide", and the periodic change of BLE during the "sub-highest tide" is more substantial. The beach recovers to a limited extent during high tide combined with weak waves. ③ Various hydrodynamic factors affect the change in BLE, and the different observation point have different responses to tidal level changes and wave forces. The BLE is more affected by deep-water wave height when observation site is beyond the surf zone, while the wave, the tidal level, and the type of broken waves inside the surf zone are main impact factors on the BLE.