Analysis and Design of Microirrigation Laterals

A method was developed for the design of microirrigation laterals based on the required average emitter discharge and the required uniformity of water application. The finite-element method was used to analyze the hydraulics of a lateral. The golden section search was employed to find the operating pressure head of the lateral that can produce the required average emitter discharge along the lateral. Analytical results show that the lateral length for the required uniformity of water application may have three solutions and the diameter may have two solutions when laterals are laid on sloped fields. The design procedure was implemented. When the required average emitter discharge, the required uniformity of water application, one parameter-either the lateral length or diameter, and other conditions are given, then the unknown parameter, the best submain position (paired laterals), and the operating pressure head can be accurately obtained using personal computers. A flowchart of the computer program for design of the length of paired laterals is included.