Red tide is one of the serious water environmental problems in the East China Sea, and it is difficult to predict the pollution scales. In this paper, the particle tracking model based on Lagrange method to simulate dispersion and advection and random walk of mass particles is employed to simulate a red tide event in the East China Sea occurred in May, 2014. In the numerical model, both tidal current and wind are included to consider the effects on the dispersion and transport of particles, and the verification results demonstrate that the model has a high accuracy for predicting the transport of red tide. The numerical simulation of the red tide event indicates that the local tidal current and wind are the dominant driven forces of red tide. The rotating tidal current in the sea area has a small residual current, thus the net transport of red tide by tidal current is limited. While the drift velocity and acceleration effect due to wind have a significant contribution to net transport and diffusion scale of red tide. The net transport direction of red tide is consistent with the main direction of wind. The application of particle tracking model could achieve the quick prediction of red tide, providing effective data and information for the warning and prevention of red tide disaster.
In recent years, the improvement of environmental-protection awareness las led to an increasingly concerned about the environmental problems such as water pollution, and the Water Environmental Science has gradually developed in the course of dealing with various environmental problems (Kuang et al., 2011). Red tide disaster is one of many issues in water environment. Since the 1990s, the number of red tides disaster in China has increased yearly, and the increased biological species and the enhanced toxicity have caused enormous losses to human society (Guo, 1994; Qi et al., 1994). In 2013, there were 46 red tides occurred in China coastal area. Among these red tides, 7 times of red tides were found being toxic and the dominant species was mostly Prorocentrum of East China Sea found in the coastal area of Zhejiang (SOA, 2013). In the same year, 56 times of red tides were found to affect an accumulation area of 7290 km2 in China. The highest recorded occurrence frequency of red tides was found in the East China Sea with a dominant species of Prorocentrum during May and July every year (SOA, 2014).