STUDY ON MECHANISM OF BACK-SILTATION IN THE DEEP-DRAFT WATERWAY OF THE YANGTZE ESTUARY, AND EVALUATION OF ENGINEERING MEASURES

Since the 92.2km-long , 350m-wide and -12.5m-deep draft channel was successfully achieved in the South Channel and the North Passage in the year 2010 , high siltation was found to temporally take place in the wet seasons , and spatially concentrate in the middle reach of the North Passage, where is consistent with the location of the traditional turbidity maximum zone (TMZ) of the Yangtze Estuary. The data from 2011 to 2015 show that the average annual siltation in the draft channel reached 80 Million m3 per year. With systematic analysis of the sediment source and comprehensive investigation on the mechanism of the flow and sediment transportation and siltation in the North Passage, this paper reveals a major cause of the back-siltation in the middle reach and subsequently discusses several engineering measures proposed to reduce the siltation . The final-selected engineering measure has been implemented quite recently , and the preliminary study shows that desired effect has been produced by the engineering measure.