Hydraulics and Uniformity for Drip Irrigation

by I-pai Wu, (M.ASCE), Assoc. Prof. of Agri. Engrg.; Univ. of Hawaii, Honolulu, HI,
Harris M. Gitlin, Assoc. Extension Specialist in Agri. Engrg.; Univ. of Hawaii, Honolulu, HI,

Serial Information: Journal of the Irrigation and Drainage Division, 1973, Vol. 99, Issue 2, Pg. 157-168

Document Type: Journal Paper

Abstract: A drip irrigation system consists of a main line, submains, and laterals and emitters. The flow condition in the submain and laterals is steady, spatially varied with laterals outflows; the discharge is decreasing with respect to the length of the line. By considering them as smooth pipes, Blasins equation for friction coefficient is used to determine energy drop between outlets along a drip irrigation line. The energy gradient line is not a straight line but a curve of exponential type which can be determined by calculating energy drop of all sections along the line. A simple way of estimating energy gradient line with only about 1% of error can be done by dividing the line into three or four segments and using the average discharge for each segment to calculate energy drops along the line. The pressure distribution along the line can be determined for both level and sloping surfaces. Uniform water application along a drip irrigation line can be achieved by using different size of emitters, length or size microtube, and spacing between emitters.

Subject Headings: Trickle irrigation | Irrigation systems | Pressure distribution | Gradually varied flow | Outflow | Spillways | Friction | Curvature |

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