Experimental Study On Water Temperature Released From Multi-level Intake Structure Of Nuozhadu Hydropower Station

Huge water area is formed and the flow gets slower after the reservoir is full withwater. Most of the reservoirs have a character of thermal stratification, which isdifferent from the natural river. The water temperature presents thermal stratificationalong vertical direction, which could vary considerably to20℃from surface tobottom. The traditional intake structure is located on the bottom of the reservoir. Andthe bottom withdrawal, which has low temperature, leads to cold water pollution inthe downstream and contributes to adverse effects of ecological environment.In order to reduce the influence on the downstream, multi-level intake structurewith stop-log gate, is widely applied to hydraulic engineering.Taking Nuozhadu hydropower station as an example, this paper presents a modelexperiment; gives the result of the water temperature released from the multi-levelintake, according to the scheme operation of stop-log; give the water temperaturereleased on the condition of the same thermal stratification structure but differentoperation mode, also provide the analysis of the influence of the operation mode onthe water temperature released. This paper presents the conclusions as follow:According to the scheme operation of stop-log, focusing on the thermalstratification of the typical year, this paper presents the experiment. And theexperiment gives the water temperature released in every month of the typical normalyear, typical dry year, and typical wet year. The water temperature withdrawal is closeto the surface layer temperature, which has its function on reforming the environmentin the downstream.According to the typical month, the experiment studies the influence of theheight of the stop-log on the water temperature released. The water temperaturereleased is obviously increasing, when the height of stop-log increases. And the extentof the water temperature released elevation is depends on the height of the stop-logand the thermal stratification.