Adverse slope density flow and its ecological effect on the algae bloom in Xiangxi Bay of TGR during the reservoir impounding at the end of flood season

The flow velocity and the water quality parameters in the Xiangxi Bay were continuously monitored during the impounding of Three Gorges Rreservoir(TGR) from Sept.25,2007 to Oct.16,2007.The results show that the water of the mainstream of TGR flowed backward into the Xiangxi Bay in density current in different plunging depth,early at the bottom,later at the middle depth and on the surface at the end,which was caused by the water temperature difference and turbidity difference between the main stream of the TGR and the Xiangxi Bay.The surface water velocity of the Xiangxi Bay was accelerated by density flow,which may transport the phytoplankton algae out of the bay and control the breaking out of autumn algae in Xiangxi Bay effectively.