Application Of MIKE21FM Numerical Model In Environmental Impact Assessment Of Ocean Engineering

For the environmental impact assessment of ocean engineering, it is recommended to adopt numerical stimulation to forecast and estimate the oceanic hydrology and hydrodynamics conditions. The value of hydrodynamic force shows the exact distribution of hydrodynamics conditions of the whole waters under research. And it further provides flow field for the environmental assessment and demonstration of ocean engineering. As the basis of several analyses and the essential of environmental assessment, it is applied widely in practice. Therefore, it is significant to study the application of the new numerical stimulation technology in environmental impact assessment of ocean engineering.Based on flexible triangular grid, an irregular grid, MIKE 21 FM is a new hydrodynamic model launched by DHI in Denmark. This grid makes it taking an advantage in the stimulation of water front. It can intensify easily the grid dense of the topography in shoal water and major area of ocean engineering. Furthermore, taking in consideration of the influence of wind stress, barocline and runoff at the land boundary, MIKE 21 FM performs stably with reliable calculating result, easy operation and strong post-processing function.MIKE series software, developed by DHI Company, has got extensive application worldwide. However, at present MIKE 21 FM is rarely adopted in oceanic environmental assessment. This thesis makes valuable achievement in this field. The major research and achievement are as follows:(1). Taking the flow field simulation of Shanwei harbor, in the Guangdong eastern waters, as an example, this thesis brings up the implemental method of the application of MIKE 21 FM in the oceanic environmental impact assessment, and the model construction progress to verify the simulation effects. It also points out the key consideration and the original data needed for the two dimension waters environmental impact forecast. It describes a series of supplementary procedures used together with MIKE 21 FM, and discusses the geographic data collection and processing, boundary conditions and the post-processing of maps in this module numerical simulation.(2). Compare the simulation result of the flow field of Shanwei harbor mentioned before with the actual measurement, it shows:①the error of tidal level phase between simulation calculation and actual is less than 0.25h; the peak and valley value do not exceed 0.15m; the flow velocity is not bigger than 0.05m/s; and the flow direction tendency is almost the same.②the convergence of simulation calculation is good, so that the simulated flow field can stand for the actual one. Therefore, the calculation results of MIKE 21 FM can reflect the progress and features of tide movement in the researched area, and show the real condition of the area. This provides the flow field background for engineering research and basis for the forecast and assessment of water quality, topographic scour-and-fill, and ocean current dynamic. Besides, this simulation also results in good visualization of flow field, sea floor topography and tidal current progress.(3). It takes a practical example of the application of MIKE 21 FM in environmental assessment by a land reclamation project in South China Sea. By this project, this paper expects to put up with a new method for environmental impact assessment of ocean engineering. MIKE 21 FM builds two dimension mathematical models for the area around the reclamation project, simulates the hydrodynamic force before and after the project, and displays the influence of this project on hydrodynamic force. By the compare with the actual measurement, MIKE 21 FM is testified that it can simulate the complex flows in the project stably and effectively. The simulation result is satisfying: the accuracy can meet the requirements of ocean engineering application, and its strong post-progressing is favorable to the analysis of engineering problem. Consequently, it can be widely used in the hydrodynamic force calculation of environmental assessment of ocean engineering.With stable and reliable calculation and high accuracy, MIKE 21 FM can provide an excellent calculation platform for the hydrodynamic force value simulation of offshore projects. Currently, this technology is seldom used. Therefore, the research of the application of MIKE 21 FM in environmental assessment of ocean engineering is very practical and innovative.