Research progress on monitoring of trough section in Caofeidian, Bohai Bay

Based on the bathymetric data measured in 2021 and seismic shallow profiling in Caofeidian sea area, Bohai Bay, and combined with the historical data of 2004, 2008 and 2013, the evolution in topography of Caofeidian trough was studied in terms of regional scale and water depth. Results show that the south side of the trough has been strongly scoured, and the maximum local erosion-siltation rate was −65 cm/a, which is good to maintaining the depth of the trough, and the axis movement of the trough is not obvious, except that the 35 and 40 m isobaths had a southward shifting trend, and the maximum distance of displacement was about 1000 m. The formation of the trough geomorphology is the result of the comprehensive action of internal and external forces such as tidal current hydrodynamic force, evolution of ancient Luanhe River delta and geological structure. Combined with the seismic shallow profiling, we found that the late Holocene marine sediments were missing but newer geological disaster deposits such as slumping at the bottom of the trough, forming erosional depression in the sea bottom, which may be a risk to the Caofeidian Harbor. Therefore, close monitoring to the trough shall be strengthened.