| 4670. Cablegation : A method of controlling the water supply to irrigated furrows or corrugations whereby a single, gated, pipeline is used for conveying as well as delivering individual streams of water. The quantity applied in each stream is determined by the speed of advance of a piston placed inside the pipeline and pushed by the static pressure of water; the rate of movement of the piston is controlled by a cable feeding from a drum, the rotation of which is controlled. The pipeline capacity has to be great enough so that the pipe does not flow full in the conveyance reach of the line. For a given (open) gate, there is no flow until the piston reaches it. The equivalent French term is `transirrigation`. There are surface cablegations, that can be shifted every year, and underground cablegations laid permanently in perennial crops. |
