By surveying the hydrology, water quality and phytoplankton assemblage of the Tangxi reservoir in 2003, characteristics of eutrophication and water quality management strategies, which related to watershed management and hydrodynamics, were preliminarily discussed.This reservoir had a high trophic state index (TSI), ranging from mesotrophic statue to eutrophic state, and varying temporally and spatially.TSI in flood season was higher than those in dry season, and was higher in the Xitou riverine zone than in the Xinqiao riverine zone.Microcystis aeruginosa, a species causing algal blooms, dominated in spring and early summer.Nutrients input into the upper water column were mainly from land runoff, due to high population and heavy pollution in the watershed.Consequently, treatment of domestic waste and reasonable fertilization in agriculture and increasing vegetation coverage in the catchment of the reservoir are necessary for lowing nutrients loading to the water body.As strong water column stability is crucial to the occurrence of cyanobacteria bloom in this reservoir, regulating the outflow and destratifying the water column vertically, which can cause water column well-mixing, are recommended as a hydrodynamic method to control cyanobacteria blooming.
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