闽江河口三维潮流和余流特征及污染物运动轨迹的数值模拟

基于河口、陆架和海洋沉积物(ECOMSED)模型,将干湿网格判别技术引入潮汐潮流的漫滩过程,建立闽江河口的三维斜压潮流数值模型;开展闽江口潮流、余流的三维动力学特征研究,并基于Lagrangian粒子示踪法进行污染物迁移轨迹的模拟.结果表明:潮流受闽江径流作用影响明显,落潮流速大于涨潮流速;与涨急时相比,落急时的流速呈现明显的分层现象,且随水深的增大而逐渐减小,流速减小的幅度较大;北支水道余流强度大于南支水道;垂向上,表层余流流速大于底层余流流速,表、中层余流以落潮余流为主,而底层余流则以涨潮余流为主.粒子追踪的模拟结果表明:涨憩时刻是较理想的排污时间,梅花水道与川石水道以南沿岸是较理想的排污口位置,表层排放的污染物更容易且更快向闽江河口外迁移.

Numerical Simulation of Three-Dimensional Characteristic of Tidal Current and Residual Current and Motion Trajectory of Pollutants in Minjiang Estuary

Based on estuarine, coastal and ocean model system with sediments(ECOMSED)model, a three-dimensional prognostic tidal current numerical model of the Minjiang Estuary was established by introducing the tidal current flood plain process through the dry-wet grid identification technology. The three-dimensional dynamic characteristics of tidal current and residual current in the Minjiang Estuary were studied, and the pollutant migration trajectory was simulated based on the Lagrangian particle tracer method. The results showed that the tidal current was significantly affected by the Minjiang runoff, and the velocity of the ebb tide was greater than that of the rising tidal current. Compared with the floor tide, the velocity of the ebb tide presents obvious stratification, and gradually decreases with the increase of water depth, and the velocity decreases greatly. The intensity of residual current in the northern branch channel was greater than that in the southern branch channel. In the vertical direction, the surface residual current velocity was higher than the bottom residual current velocity, the surface residual current and the middle residual current were dominated by ebb tide residual current, while the bottom residual current was dominated by flood tide residual current. The simulation results of particle tracking showed that the time of flood slack was the ideal time for pollutant discharge, and the south coast of meihua waterway and chuanshi waterway were the ideal location for pollutant discharge, and the surface pollutants were more easily and faster to migrate to the outside of the Minjiang Estuary.