To alleviate the problem that the water level drops more and more seriously in recent years, Jiangxi province proposes to set up regulation gates at each estuaries of Ganjiang river to raise the water level in Nanchang city during the dry season. The operation of this project will raise the upstream water level, which means the sediment transport rate will decrease and lead to deposition problems. In order to find out the deposition area and development trend, we carried out the suspended sediment deposition test on an existing physical model. The study shows that the upstream sediment is mainly deposited in the reaches near the two deltas. Some special topographic features are more likely to cause siltation, such as the wide and deep thalweg and the backflow areas at the downstream of convex banks. After the operation of the project, the erosion trend of the upper reaches of the central and southern branches will change to siltation, and the siltation of the upper reaches of the Western branch will be further strengthened. 15 years later, with the decrease of the upstream sediment intensity, the sediment siltation phenomenon will gradually move to downstream, however this will be a long process.
The water intake of a new water supply project of Lushan City is located on the opposite side of the LaoYeMiao in Poyang Lake. Dredging is required between the shore and the deep trough to allow water to be introduced into the intake during low water season. Based on the intake dredging project, this study established a numerical model of water and sediment transport of the research area. The model is verified in terms of water level, flow velocity, erosion-deposition rate using hydrological and topographical data. The characteristics of water flow and erosion-deposition, before and after the implementation of different dredging schemes, are studied and the influence by dredging project are analyzed from the hydrodynamics perspective. The simulation results show that the water level and flow velocity change before and after the dredging project is less than 0.002m and 0.1m/s. The dredging area before and after the project shows deposition, and the average deposition rate changed by 0.01m/year. research shows that the dredging project only affects the erosion and deposition of the dredging area. The adjustment of the dredging scheme will not have a significant impact on the deposition rate and distribution of the area. The research results can provide a scientific basis for the argumentation and optimization of the water intake dredging scheme.
In jiangxi province, china, a new river will be excavated in the southern part of Qinglan Lake to drainage the main flow of Fuhe River into the Lake to improve the local flood prevention and navigation problems. A physic model is established to analyze the changes of flow characteristics under different engineering schemes. The research shows that water level decreases 1.91m, flow velocity of the upstream increases to 4.83 m/s, under P=5% River flood, which means the diversion engineering can significantly relieve the local flood pressure, but increase the scouring risks of wading buildings such as piers and embankments. Then the further optimization study shows that scheme 3 not only reduced the engineering quantity, but also decreased velocity increase rate from 61% to 48%.
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