Study on Outlet Height Optimization of Behind-Levee Drainage Pumping Stations

Abstract

In order to save operation cost of the behind-levee drainage pumping station, aiming at large amplitude of variation of the outer river water level, we put forward optimization method of outlet height of the pumping station. The construction cost of outlet projects of the pumping station, such as outlet sump, culvert through levee and sluice gate et al., were calculated. The calculation method of operation cost of the pumping station was proposed according to the energy performances of pump system, the combination of inlet and outlet water levels and annual operation hours. The relational model between the construction cost of outlet projects, the operation cost of the pumping station and the position height of the culvert through levee were established. Taking a typical project as an example, under the premise of guaranteeing the engineering safety and drainage requirements, the optimal position height of the culvert through levee was determined with the target of minimum sum value of construction cost of outlet project and operation cost of pumping station in the project lifetime. The results indicate that when the outer river water level and its variation and annual operation hours are certain, the position height of outlet sump and culvert is the main factor which affect construction cost of outlet project and operation cost, and there must be an optimal position height of outlet sump and culvert that can make the total cost minimum. In the example, assuming that lifetime of the pumping station is 25 years and the annual operation hours are 360 h, when the depth from the levee crest to the top of culvert is optimal height 1.75 m, the total cost is minimum; the annual operation cost can be reduced by 8.13% and the total cost can be saved by about 72.6 thousand yuan compared with using outlet open channel.