Design of microirrigation submain units

A method was developed for designing microirrigation submain units. The lateral discharge equation was used to express the relationship between the discharge and pressure head at the inlet of a lateral to allow a submain unit to be considered as a lateral and a lateral as an emitter. The finite-element method was employed to analyze the pressure head and discharge distributions along laterals and submain. The golden section search was applied to find the operating pressure heads of the lateral and submain corresponding to the required average emitter discharge. When the required average emitter discharge, the required uniformity of water application, one parameter-either the lateral length or diameter, one parameter-either the submain length or diameter, and the field conditions are given, then the unknown parameters, the best submain position (paired laterals), and the operating pressure head of the submain unit can be accurately designed using a personal computer.