Using mooring hydrodynamic observation, cross-shore profiles, and topographic-map and satellite-image comparisons, this study shows dramatic coastal erosion on the Qinhuangdao coast (northeast Bohai Sea, China) between 1986 and 2000, with an average retreat rate of 3.7 m/y. While the retreat rate during 1996–2003 decreased to 1.5 m/y, serious coastal erosion was found around river mouths, such as the Tang, Dai, Yang, Dapu, and Renzaohe Rivers, as well as Qilihai Lagoon, with the maximum of >7.0 m/y.
Sediment starvation induced by dams mainly caused this fast coastal retreat. Sediment flux of the Luan River, the dominant fluvial sediment source in the study area, declined to only 9.0% of the levels before the impoundment of two large dams in 1979. Sharply reduced sediment supply disrupted the stability of sediment transport as well as the beaches' self-recovery processes after storm surges. Coastal erosion was further intensified by coastal engineering and tourism activities.