Effect of Different FCLL Regulation Scenarios of the Three Gorges Project on Dam Navigation and Reservoir Sedimentation
Abstract
The effect of different FCLL (Flood Control Limited Level) on the shiplock water depth on sill, flow conditions in the approach channels and sedimentation in the reservoir after the Three Gorges Project was put into service, was examined based on physical model experiment and mathematic model calculation, with a view to understanding the effect of FCLL on dam navigation and reservoir sedimentation. Results indicated that when the flood flow is less than or equal to 35000m3/s, the shiplock water depth on sill, velocity and regime in the approach channel entrance area and the connection would remain generally the same under different FCLL regulation scenarios, and all of them would provide the required flow conditions for navigation; when the flood flow is equal to or larger than 45000m3/s, subject to the lowered dam-front level, navigation would be suspended for short periods under the double FCLL scenario; a higher percent of longitudinal and traverse velocities in excess of the normal rate would be expected in the approach channel entrance area and the connection under the multi-FCLL scenario, and the navigation flow conditions would be somewhat deteriorated. Neither double FCLL nor multi-FCLL would be much effective in mitigating sedimentation within the first 30 years of reservoir service, and better performance could only be expected when the reservoir has served 50 years. This would take place typically in the constant backwater area, with limited performance in the variable backwater area too. By comparison, double FCLL would be more effective in mitigating sedimentation than multi-FCLL. Given the complexity of the problem, further investigation is recommended on the dam-front FCLL regulation schemes after more prototype observation.
Keywords
Three Gorges Project, FCLL, Dam navigation, Reservoir sedimentation
DOI
10.12783/dteees/ese2017/14345
10.12783/dteees/ese2017/14345
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