Research Of The Response Of The Morphological Process At Yangtze River Estuary To The Changes Of Water And Sediment Discharges

Estuary is an area where interactions are very strong between land and sea and between natural processes and human activities. The hydro-engineering projects in the drainage basin such as Three Gorges Project and the south to north water transfer project would result in the decrease of water and sediments discharging into the estuary, the change of the morphological process and dynamic aggradation, and therefore affect the estuarine environment. The paper takes the downstream of Xuliujing at the Yangtze River Estuary as a study object. By means of multi-subjects method, the response mode between the change of water and sediments discharging into the estuary and the dynamic evolution of estuarine landform will be set up.According to actual measured data and former research production, the water dynamical condition and the sediment environment are analyzed. Supported by GIS, different period digital elevation model of the Yangtze River Estuary are established. By research means of estuarine coastal morphological process and dynamic aggradation, the dynamic evolution of river bed in the Yangtze River Estuary is clarified since 1842.Supported by statistics and hydrological analytical method, the trend and characteristics of changes in water and sediment discharge in the Yangtze River basin are probed. Human impacts on water and sediment discharges of the Changjiang River drainage basin are opened out. The effects of the projects in the drainage basin such as Three Gorges Project and the south to north water transfer project on the change of water and sediments discharging into the estuary are discussed. the Evidences in the past and the trend for coming decades of the effects of the change of water and sediments discharging into the estuary on the dynamic evolution of estuarine landform are analyzed.The research results show that: Along with the decreasing of sediment discharging, the underwater bars are eroding and the channel volume is growing in south branch, south channel and the upside of north channel, which will have negative response to the channel in mouth bars; Along with the decreasing of sediment discharging, the change of the sandiness in mouth bars is small, but the long-playing decreasing of sediment discharging will still make the speed of siltation decrease, which will influence the exploitation and using of estuarine tidal flat resource.