Investigation of fast ice hazards in daling river estuary

North Liaodong Bay in China experiences severe sea ice disasters. In this field study, fast ice hazards were investigated in Daling estuary, located on the northern coast of Liaodong Bay. Ice conditions were investigated according to average-iced year, severe-iced year, and lighter than the average-iced year. The results revealed that the bulge part of the ice hummocks is very strong while the lower part is as loose as slush because these two portions are controlled by air and water temperature, respectively. The distribution and formation of ice hummocks is influenced by various factors such as seabed topography, tides and wind. The ice sheets in the fast ice zone are larger, thicker, and stronger than drifting floes. The thickness of drifting floes can be calculated by surveying the growth of ice cover in tidal channels within the fast ice zone. The ice pile-up hazard affecting an artificial island and its slope was due to the movement of floating ice sheets being blocked by the artificial island and lack of buckling between the thick ice sheets. Therefore, the total kinetic energy of the ice sheets could cause a small portion to pile and climb up. It is difficult to prevent risk to the artificial island structure. The pile tilt was due to the thickness of ice sheets exceeding design standards and the ice hummocks blocked by the pile could exert a large additional flow force on the pile for a sustained period. Ice-breaking measures should be adopted to prevent sea ice disasters resulting from oceanic fast ice. •The distribution features of fast ice in typical years were given based on field investigation.•The mechanisms of fast ice hazard on the artificial island and the single pile were given based on field work.•The thickness of floes can be calculated according to the growth of ice layers on the tidal channel in the intertidal zone.•The scope and total amount of fast ice should be identified as an index of annual ice conditions.