Erosion-siltation in the channels in Zhangjiabu Harbour, Wendeng, Shandong

The Zhangjiabu Harbour is located in Jinghai Bay in the southern part of Shandong Peninsula, and is a tidal canal-drowned valley bay. Anatomizing the erosion-siltation characteristics is valuable for clarifying the dynamic geomorphological evolution of the harbour and the impact of human activities on the study area. Based on the bathymetric data of charts in 1980, 1997, 2009 and 2021, isobath overlay analysis, and digital quantitative erosion and siltation calculation were conducted in GIS technology. The changes of isobath, erosion and siltation, and topography profiles in the harbour since 1980 were analyzed. Results show that the harbour is currently in siltation status with an average deposition thickness of 1.08 m during 1980-2021. The 0 m isobath silted into the center of the harbour and the shallowed area by siltation at 5 m isobath was reduced by 67.01%. The deposition thickness on the west side of the harbour is much larger than that on the east side from Tangzi Spit to Changhuikou Spit. Since 1980, the construction for aquaculture on both sides of the harbour has changed the local tidal-current movement conditions, which had caused a change from siltation to erosion within the harbour and the ebb delta outside the Changhuikou Spit was pushed back, and finally, the geographical situation of Zhangjiabu Harbour has changed profoundly.