A MODEL FOR HYDRAULIC DESIGN OF IRRIGATION LATERAL LINES
There are several models for hydraulic designs and optimization of lateral lines depending on the existing pressure head profile and flow which allows designing longer lateral lines, therefore decreasing the cost of the system implementation. A model has been developed to calculate the pressure head and required flow rate at the inlet of lateral line using the back step method. A set of equations was implemented in an algorithm in the R language. For the calculations, the following variables must be provided: pressure head at the end of the lateral line (Hend), coefficients K and x of the characteristic equation (flow-pressure) of the emitter, pipe diameter (D), emitter spacing (Se) and number of emitters (Ne). For the evaluation of the model, the pressure head at the end of the lateral line, the pipe diameter and the number of emitters were varied within the established limits. Relationships between these variables were established by regression analysis using the least-squares method. The model shown in the study was suitable for the calculation of the pressure head and flow rate profile along the lateral line. The power, plateau, exponential and linear equations were adjusted to describe these relationships. These equations can help in the design of irrigation systems by simplifying the procedures in order to meet the design criteria. Also, the proposed equations allow evaluation of the systems still in the design phase.