The Application Research Of Delft3D Model In Environmental Protection Dredging Of Inland Waterway

The strengthening of sediment accumulation will have a negative impact on the normal operation of channels, and even lead to some channel block, some port stop work. At the same time, the sediment pollution of many inland waterways is very serious in recent years. If we do not treat it, pollutants will be released back into the water, it will have a bad influence on water quality. Therefore, environmental dredging is in urgent need to deal with sediment pollution of inland waterway.Although environmental dredging can remove polluted sediment of river, has good help for navigation and the removal of pollutants in sediment, it can also cause sediment suspension, and the pollutants in sediment diffuse into the water, causing pollution of water environment. So the water environment numerical simulation in the process of dredging can predict the impact of dredging on the water environment, provide reasonable theory basis for dredging operation.The main content of this paper is to simulate the water environment in the process of waterway dredging in the Three Gorges. the typical deposition reach of the Three Gorges Reservoir, Zhongxian Huanghua city reach is selected to numerically simulate. The Delft-3D software is used to simulate the hydrodynamic and water quality condition in the dredging process of Zhongxian Huanghua city reach. At first, the hydrodynamic of Zhongxian Huanghua city reach is simulated, then on the basis of the hydrodynamic, dredging point discharge pollutants in the form of point source discharge, the diffusion condition of inertia pollutant in the water is simulated.In this paper, the content of hydrodynamic simulation is the hydrodynamic condition within 2 days of Zhongxian Huanghua city reach, providing a basis for water quality simulation. Comparing the velocity distribution of simulation and the terrain depth map of the river, obtaining a conclusion which is the smaller the flow velocity is, the deeper the water is. It is because sediment deposition is little in high velocity areas by the effect of scouring, while the water is very shallow in low velocity area by the effect of many years of sediment deposition. The simulation result conform to the measured data, so it can be used for water quality simulation in the next step. the numerical flow field is not stable in the early stage of the hydrodynamic simulation, so it cannot be used in water quality simulation. When the calculation of flow field is basically stable, it can be used in the calculation of water quality.In this paper, the content of water quality simulation is the river water environmental change during the 12 hours of dredging process, and the 8 days after the end of the dredging. can simulate the impact on water environment during dredging projects, and the recovery after the dredging water. The impact on water environment during dredging process and the recovery of water quality after the end of dredging can be simulated.By means of the water quality simulation of Zhongxian Huanghua city reach, we can obtain that the influence of dredging process on river water environment is obvious. Especially in the area not far below the dredging point, the pollutant concentration rises rapidly, and rises a lot. But the farther away from the dredging point With the direction of flow, pollutant concentration rises less, and rises more slowly. After the end of the dredging project, the water quality of Zhongxian Huanghua city reach can recover quickly. One day after the dredging, pollutant concentration almost have returned to the background value, the influence of dredging almost have eliminated, the water self-purification ability is good, the influence of dredging project on water environment can recover quickly.