Analytical Relationships for Designing Rectangular Drip Irrigation Units

Approximate analytical expressions were obtained that relate uniformity indices of water distribution in rectangular drip irrigation units as a function of the variables that define that unit: lengths and diameters of laterals and submain, spacing of emitters and laterals, ground slopes, parameters of the emitter discharge equation, and equivalent lengths characterizing local losses. The proposed expressions offer greater precision than might be needed in irrigation practice. They do not require iterative calculations and improve the procedures normally used. They may be useful in the design of drip irrigation units and in their evaluation and management. An example of their application is offered. The proposed relationships simplify studies of the sensitivity of variables involved in optimum hydraulic design. Users are thus allowed a rational understanding of their influence, improving that which can be gained from computer programs. Graphs obtained with the mentioned expressions are also offered. They can be of interest, although their use is not treated specifically in this paper.