Author(s): Yan Yixin; Xu Fumin; Mao Lihua
Linked Author(s):
Keywords: The stage regulation work; The yangtze river estuary; The jiuduansandbank; Nonlinear three-dimensional numerical model; The north channel; Tidal discharge; Euler’s residual flow; The grions section; The north jetty; East sandbank trench
Abstract: The stage regulation work of deep water channel of the Yangtzs River Estuary and the topographic change of the Lower-Section of the Jiuduan Sandbank after regulation were simply described. Nonlinear three-dimensional numerical model under the ■ coordinate system was applied in this paper, the model's numerical scheme, boundary conditions were presented here, and the model was verified with field observations including both the field water surface elevations and field current velocity. Topographic change of the Lower-Section of the Jiuduan Sandbank after and before theⅠstage regulation work (from May 1997 to March 2000) was obtained based on field measurements, problems to be solved in this paper were concluded as: why the Lower-Section of the Jiuduan Sandbank moved towards north direction, where the silted sediment came from, whether it came from Jiuduan Sandbank itself or from other area. To solve the above problems, concepts of tidal discharge and the Euler's residual flow were introduced to jointly interpret the hydrodynamic mechanics of sediment movement and topographic change for the first time. By using identical boundary conditions and different topography in May 1997 and March 2000, changes of the tidal discharge and the Euler's residual flow from May 1997 to May 2000 in the North Channel area were numerically simulated based on the nonlinear three-dimensional numerical model. Finally, the effect of he hydrodynamic change mechanics in the North Channel on the topographic change of the Lower-Section of the Jiuduan Sandbank was analyzed comprehensively, the results showed that sediments silted at the northern part of the Lower-Section of the Jiuduan Sandbank were not come from the Juduan Sandbank but from the Grions Section, the northern part along the North Jetty and the vicinity of the East Sandbank Trench, the simulated hydrodynamic mechanics were in good agreement with the topographic change, so the model and the study method used in this paper could not only serve as a useful research method but also provide scientific basis for the decision making of future regulation work.
Year: 2001