River sediment fluxes to the sea contribute to the morphological evolution as well as environmental and biological conditions of estuaries and their adjacent coasts. Especially for river basins that are dominated by a monsoonal climate, extreme high discharges can occur due to intense rainfall during the flood season, which will considerably affect the amount of sediment that is transported to the sea. In this paper, 4 major floods of the Yangtze River (2 extreme floods, one affecting most of the basin in 1954, and one more pronounced in the upper reach in 1981; and 2 large floods, one impacting mainly the middle reach in 1983, and one affecting most of the basin in 1998) are analyzed as these provide a unique opportunity to investigate fluvial sediment characteristics to the sea affected by major flooding. Results reveal that more sediments were delivered to the sea during the flood season when regional-sized major floods occurred, and this was even more pronounced when major floods occurred in the upper reach of the Yangtze River. Sediment retention in the middle reach of the Yangtze River during the major floods significantly reduced the amount of sediments reaching the sea. As for the flood season of 1981, the sediment size distribution to the sea was not significant different than that of the perennial average. However, coarser-grained sediments were delivered to the sea during July 1983 due to the remarkably high water discharges at that period. These findings can provide enlightenment regarding the timing of wetland restoration and interpretation of previous flood deposits in the deltaic zones of the Yangtze River.
Sediment characteristics of the Yangtze River during major flooding - ScienceDirect