STUDY ON MUDFLAT EVOLUTION OF NANHUI EAST SUBMERGED SPIT,YANGTZE ESTUARY,CHINA

摘要

Nanhuieast submerged spit, which has complicated dynamic conditions, sediment transport, sedimentological processes and morphological evolution, is located in the transitional zone between the Yangtze Estuary and the Hangzhou Bay. The comparison of digitized bathymetric charts shows that the spit has extended towards southeast at the rate of 72m yr~(-1) and its area above -5m isobath has remained unchanged in the past 100 years. However, its northern side is suffered from scour due to strong discharge current of South Passage, its eastern side is suffered from the action of rotary tidal current, and its southern side is suffered from tidal currents of Hangzhou Bay. These combined actions of dynamics result in Nanhui submerged spit extending southeastward. The transportation of the eroded sediment in the upside of South passage after implementing the first regulation engineering of Yangtze Estuary Deepwater Channel shows a sediment passage in the nearshore of Nanhui spit through which the sediment from the Yangtze Estuary transport into the Hangzhou Bay.