Comparative Analysis of Hydraulic Calculation Methods in Design of Microirrigation Laterals

The hydraulic design of a lateral or a submain unit in a microirrigation system has been a problem tackled by many authors. In applications of previous analytical approaches for trickle lateral hydraulic computation, it is generally assumed that the emitter outflow along the lateral is constant. However, significant deviations from accurate numerical solutions in hydraulic analysis could be caused by this basic assumption of constant emitter outflow. Recently, some alternative analytical methods with more accurate results were developed based on the spatially variable outflow approach. In this study, seven hydraulic calculation methods were analyzed and classified for comparative purposes from points of view such as solution methods, basic assumptions, formulations used, and differences in application. A comparison test was applied to the seven design examples with the special limited design conditions of some calculation methods, such as emitter discharge exponent, to cover various combinations of irrigation parameters, varying emitter discharge exponents, and different ground slope conditions. The results were shown graphically in dimensionless form. These figures could also be used as design charts in practice.