In-situ observation of seabed vertical deformation in Yellow River Delta under storm surges

Abstract

Sediment destruction poses a major risk to marine engineering facilities in river delta areas. The vertical deformation of seabed induced by storm surges is one of the major causes of sediment destruction. In this study, an in-situ observation system for monitoring the seabed vertical deformation was developed. The system includes a Paroscienctific high-precision water pressure sensor, a tide & wave recorder, and an Acoustic Doppler Current Profiler (ADCP). A processing method of the high-precision water pressure data was established. The advantage of this data processing method is that it allows us to obtain the water depth variation in shallow sea area based on the observed water pressure data. The system and the processing method were applied in an in-situ observation, which was carried out in Chengdao Sea area in the Yellow River Delta from December 2020 to January 2021. During this observation, marine hydrodynamic changes and vertical deformation of seabed were synchronously monitored. Three storm surge events were observed during this period. The vertical deformation process of seabed during the storm surges was quantitatively analyzed. After the first two storm surge events, the monitored vertical settlement of seabed reached 8.97 mm. A seabed vertical deformation mechanism was established based on the in-situ monitoring data.