A Preliminary Study On Suspended Transport Characteristics In Tidal Reach Of The Yangtze River

The lower tidal reach of the Yangtze River is one important object studied by many scholars. Especially when some large irrigation works are being built these years, the harmonious relationship between flow and sediment has been changed. So a 2-D flow and sediment numerical model for the reach of TongCheng is built under the orthogonal curvilinear coordinates. Flow and sediment characters of the reach are calculated and analyzed using this model.In the model of flow and sediment, corresponding calculated mode is built using the method of volume control. And result by model calculation inosculates well with that by measured data.According to the hydrologic data of many years, characteristic discharges in flood and dry seasons are got by corresponding frequency. 14 typical divaricating channels are chosen. Diversion ratio and sediment diversion ratio are calculated under different discharge. Change of diversion ratio and sediment diversion ratio is analyzed while relationship between them is also analyzed.Because of the advantage of numerical model, 8 sections and another 16 sections are chosen to calculate and analyze sediment concentration in latitudinal range and longitudinal range. Change of sediment concentration along the reach in flood and dry season is analyzed in the mass.Finally 6 typical sections are chosen to analyze the characteristics of suspended sediment transport for this reach. Different sediment discharge under different flow discharge is calculated. And relation curve between sediment discharge and flow discharge for each section is got. Relationship between the two discharges is analyzed qualitatively. And influences of water abstraction and coarsening of suspended sediment are analyzed qualitatively using the numerical model. diversion ratio, sediment concentration, sediment dischargeThis study was supported by the joint key project of National Natural Science Foundation of China ( No. 50339010 ) and open foundation of the State Key Laboratory ( No.2005407211) .