Abstract:

In this paper,since the water flow velocity below 001m/s,the following in the tributary backwater area after the Three Gorges Reservoir Area impounded,so it can be approximately regarded as static water.The paper carried on simulating calculation to the vertical migration of cyanobacteria species by building a theoretical model of illumination influences to its vertical migration,and setting a year and a day as study period respectively.The results of the calculation revealed that the vertical migration of cyanobacteria had an obvious seasonal characteristic. Cyanobacteria stayed in the dormant period and remained at the bottom of water every winter,while they began to recover in April and entered dormancy in November when they had weak buoyancy.Cyanobacteria started to up to the water surface in May and October,and the velocity of cyanobacteria’s vertical migration increased from June to September when algae blooms could happen easily.Meanwhile,the computed results demonstrated that the speed of rising/sinking of the cyanobacteria were higher in June and September,and the water body was prone to come up rapid migration of floating/sinking vertical migration.〖JP2〗This phenomenon showed dramatic bloom outbreaks/fade at macro level.What’s more,it was from 8:00 am to 10:00 am in June that the algal blooms easily occurred,and in September,the time was from 10:00 am to 11:00 am.Predicting results and observed data had a good consistency.〖