Linking the Kinetic Energy Fraction and Equivalent Length Method for Trickle Irrigation Design under Local Losses

Abstract

New methods using analytical relationships to design drip irrigation laterals and subunits have been introduced in recent years based on the assumption that minor losses can be neglected. This assumption could be relaxed by applying the equivalent method, which makes it possible to account for minor losses, such as those caused by emitter connections, through formulas based on the rationale that an equivalent length of the drip lateral produces the same losses. However, equivalent length formulas are empirical; thus, they do not necessarily cover the entire range of conditions in the real-world contexts in which the formulas will be applied, and their extrapolation could lead to erroneous results. In this paper, theoretical equivalent lengths were calculated and linked to the kinetic energy fraction, which was considered as an alternative general procedure to compute minor losses. Therefore, the results obtained here are valid in all general contexts, because they were not affected by experimental calibrations. A methodology was suggested that extends the use of analytical relationships to design drip laterals from a previous method that neglects minor losses to a new method in which minor losses are considered. Several applications were performed for drip laterals in horizontal and in sloping fields. Results showed the reliability of this new design procedure.