Historical and Projected Future Trends of Tidal Disasters at the Qiantang River Estuary, China

Pan, D.Z.; Li, Y., and Pan, C.-H., 2020. Historical and projected future trends of tidal disasters at the Qiantang River Estuary, China. In: Bai, X. and Zhou, H. (eds.), Advances in Water Resources, Environmental Protection, and Sustainable Development. Journal of Coastal Research, Special Issue No. 115, pp. 682-686. Coconut Creek (Florida), ISSN 0749-0208.The Qiantang River Estuary is a funnel-shaped macrotidal estuary with a famous tidal bore. According to historical documents, many dynasties have recorded the tidal disasters in China. Based on historical data, the spatial and temporal distributions of tidal disasters along the Qiantang River Estuary are investigated and the future trends are projected. The wavelet analysis for the occurrence number of tidal disaster in the Qiantang River Estuary shows that there are periodic oscillations of 5 years, 17 years, 29 years, and 55 years. 55 years is the first principal period. The month distribution mainly concentrates from the 5th to the 9th month of the Chinese lunar calendar, and come to peak in the 7th month. The daily distribution mainly concentrates near the waxing cresent moon and the waning gibbous moon, partly resulted from the lunar force influence. In spatial analysis, the frequency and hot spots show significant regional differences, and have a certain concentration in Hangzhou, Haining, Haiyan and Pinghu. Tidal disasters occurrence coincides with the change of the frequency of seawall construction and coastal reclamations, and it may be the reflection of sea level change.