Discharge ducts for pumping water from a supply reservoir to a delivery reservoir

A discharge duct for discharging pumped water from a supply reservoir defined by a first minimum water level and a supply reservoir floor to an operatively higher located delivery reservoir defined by a second minimum water level and the delivery reservoir floor, the said discharge duct being defined by an inlet at one end of the discharge duct in communication with the outlet orifice of a conventional pumping device fitted at the supply reservoir; an outlet at the other end of the discharge duct, said outlet , in the operative configuration of the discharge duct, being below the second minimum water level; a peak at a location relatively closer to the delivery reservoir and at a height between h+2d+0.5 meters and h+2d+8 meters where h represents the height difference between the floor levels of the supply reservoir and the delivery reservoir and 2d represents the diameter of the cross section of the discharge duct; inclined sections leading from the peak towards the said inlet and the said outlet; the angle of inclination of the inclined sections leading to the said outlet and the said inlet being at an angle lying between 45 and 60 degrees to a virtual central axis [B-B] passing through the said peak; a siphon breaking orifice provided at the peak or within five degrees of the peak towards the delivery reservoir; and an evacuator orifice provided at a location on the inclined section leading from the peak towards the said outlet at a position 10 to 17 degrees off the peak towards the delivery reservoir.