Abstract: Algal bloom in the tributaries has become a severe water quality problem in the Three Gorges Reservoir. It is significant of identifying the mechanism of algal bloom to protect the eco-environment. In this study, the author summarized the research progress, analyzed the mechanism of algal bloom and factors affecting the bloom, and gave some control methods. The results indicated that (1) the bidirectional density current was the most prominent changes caused by the Three Gorges Dam; (2) main factors affecting the algal bloom could be considered to be the nutrients supply mode and the water stable stratification both caused by the density current. In view of this, the only method to eradicate the bloom was advised to be pollution control over the whole upstream of Yangtze River basin. Moreover, reservoir operation to change the density current’s characteristics was also considered to be feasible to control the algal bloom. Further researches and demonstrations in this respect are required.

Key words: water bloom mechanism, density current, control measure, research progress, Three Gorges Reservoir