On October 22, I interviewed officials from China’s Ministry of Natural Resources regarding the unusual water level fluctuations observed in the Bohai Sea and northern parts of the Yellow Sea. They reported that, between the evening of October 20 and the afternoon of October 21, tide gauges recorded a rise of 80 to 160 centimeters, despite the absence of significant weather systems. In response to this phenomenon, the Ministry has activated a Level 4 emergency response for marine disasters and deployed five expert teams to Liaoning, Tianjin, Hebei, and Shandong provinces to assist local authorities in assessing the situation and managing disaster investigations.

During the specified time frame, coastal areas in Liaoning reached a critical red alert tide level, while cities such as Qinhuangdao and Tangshan in Hebei, as well as Yantai in Shandong, experienced orange alert high tide levels. Additionally, on October 19, the coastal area of Nantong in Jiangsu also observed high tide levels reaching red alert. The monitoring data indicate that this abnormal water level increase was both strong and prolonged, with approximately 1-meter rises persisting for over 20 hours along the Bohai coast. This resulted in several tide gauges in Liaoning breaking historical records for high tide levels around the early hours of October 21, leading to instances of seawater backflow in Liaoning, Hebei, and Tianjin. Notably, there are no documented cases of such occurrences, both domestically and internationally, thus far.

Experts from the Ministry analyzed that this unusual increase in water levels is primarily linked to the rebound of large-scale storm surge waves from the open sea, along with the effects of astronomical high tides. Before this event, strong storm surges were recorded along the Bohai Gulf, Laizhou, and the Shandong Peninsula between October 18 and 19 due to the combined impact of cold air and an offshore cyclone. Following this, from the afternoon of October 19 to the daytime of October 20, the Bohai coast experienced significant water level reductions of over 100 centimeters, which resulted in a substantial accumulation of seawater offshore. This accumulation then coincided with local astronomical high tides during the night of October 20 to the early morning of October 21, contributing to the elevated tide levels observed along the coasts of Liaoning, Hebei, and Tianjin.

Currently, no unusual water level increases have been detected south of the Yangtze River estuary or in other global maritime regions during this time frame.