Influences of wind field on flow regime and algae blooming in Dianshan Lake

摘要

Wind rose analysis method, two dimensional hydrodynamic model and particle tracer model are adopted to systematically study wind field features, flow field variation, and migration, spreading and accumulation processes of the internal and external cyanobacterial boom in Dianshan Lake. The results show that the wind direction in Dianshan Lake varies with seasons; the main wind direction is ESE in summer and autumn, and is NNW in winter and spring. Wind has great effects on the circulation patterns of the lake. In the case of no wind, the lake is mainly influenced by the upstream and downstream flows. River flow enters into the lake during flood tide, while the lake discharges during ebb tide, and there is no circulation occurred; the clockwise and counterclockwise circulations are generated respectively in the north and south of the lake under southeast wind, and similarly for northwest wind only the circulation directions are opposite. Upon different wind and flow fields, cyanobacterial boom is drifting to the windward lakeshore, and is prone to form the algae accumulation area.