Designing Trapezoidal Drip Irrigation Units laid on Flat Fields

Abstract

In recent years, significant effort has been made to derive simple analytical solutions for designing one-lateral and rectangular drip irrigation units. In contrast, the trapezoidal shape often aligns with the natural subdivision of agricultural fields and serves as a foundational model from which rectangular and triangular forms are particular cases. Following a similar approach to previous works, this paper extends the analytical solutions derived for rectangular shapes to trapezoidal shapes, showing that the rectangular unit (RCT) is a particular case of the new solution. A comprehensive analysis of the performance of trapezoidal units was conducted using novel analytical solutions based on the pressure head tolerance concept. Two distinct types of trapezoidal units were studied based on the feed point: major base-fed (MJR) and minor base-fed (MNR). Interestingly, when the trapezoidal unit is fed from the major base (MJR), the hydraulic performance of the drip irrigation system is more efficient compared to both RCT and MNR. This is because lower manifold inside diameters, inlet pressure heads, and coefficient of variation of pressure head distribution (PHD) are obtained, thus MJR is higher recommended than RCT and MNR. Several applications showing the validity of the suggested procedure are performed and discussed.