| As a fish passing facility,fishway is an ecological remedy measure for new water conservancy project.It can not completely eliminate the ecological damage caused by dam,such as the loss of river ecological environment or the loss of river longitudinal connectivity.However,it can reduce the the negative impact of these constructions on ecological environment to a certain extent,so as to enhance the ecological compatibility of water conservancy project.This paper takes the fishway of Tangba Hydropower Engineering as the research object.By establishment a two-dimensional mathematical model for numerical simulation,the upstream and downstream flow field of Tangba Hydropower Engineering were studied.This paper analyze the reasonable arrangement range of the entrance and exit of the fishway.Verification of the rationality of the layout and size of the fishway chamber by the physical model tests of the local fishway.Through the whole fishway physical model tests to analyze the fish passing ability of the fishway.The research contents and results are as follows:(1)Summarizes the development history and research progress of fishway at home and abroad.According to the dam-passing fish species,the classification and characteristics of the fishway,the layout and design scheme of the fishway of Tangba Hydropower Engineering are proposed.(2)Through the two-dimensional mathematical model tests,the upstream and downstream flow field of Tangba Hydropower Engineering have been studied under various working conditions.The optimization scheme of the upstream and downstream flow field and the suitable range of the position of the fish inlet and outlet have been analyzed.The analysis results show that the appropriate position of the fish outlet is130 m upstream of the hydropower station intake,close to the right bank.And the fish outlet guiding measure have a very limited impact on the flow velocity;There is no obvious change in the flow field of the fishway inlet with different opening positions of generator set.Reducing the terrain at 100 m downstream of the power station has little effect on the inlet velocity of fishway.The fish inlet of the fishway is suitable to be arranged on the right bank of the river below 100 m downstream of the power station.(3)The physical model tests of local fishway are used to study the flow pattern inthe fishway,the change of water depth along the path,the velocity distribution in the chamber and the maximum velocity at the vertical narrow fracture under two different water depths.The results show that the flow pattern of vertical slot is good,the flow pattern of each chamber is stable,and the distribution of velocity is reasonable.So the fishway design scheme meets actual fishway requirements.Although the maximum velocity measured by the model slightly exceeds the design velocity of the fishway,it should not affect the migration of fish.The velocity distribution in the vertical slot is nonuniformity.The area where the velocity exceeds the standard only occurs in the local range of the vertical slot.(4)The physical model tests of whole fishway are used to study the flow pattern in each chamber,the change of water depth in each chamber,the velocity distribution in each chamber and the maximum velocity at the vertical slot under different working conditions.The results show that the design and layout of the fishway are basically reasonable,but the velocity at the vertical slot in the part of the fishway inlet exceeds the standard.Considering the nonuniformity of velocity distribution of vertical slot,it will not affect the migration of fish.When the depth of fishway outlet is less than 2.0m,the velocity of vertical slot can be reduced to less than 1.2m/s by properly increasing the operating depth of fishway inlet to 1.65 m.It is suggested to take corresponding water replenishment measures to solve the problem of low flow velocity at the fishway inlet under the condition of deep water,so as to achieve the corresponding flow velocity and flow pattern at the fishway inlet. |
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