Gravity-fed drip irrigation design procedure for a single-manifold subunit

A simple procedure was developed for the design of low-cost, gravity-fed, drip irrigation single-manifold subunits in hilly areas with laterals to one or both sides of the manifold. The allowable pressure head variation in the manifold and laterals is calculated individually for different pressure zones, and the manifold subunit design is divided into independent processes for laterals and manifold. In the manifold design, a two-stage optimal design method is used. In the first design stage, the pipe cost is minimized and a set of optimal manifold pipe diameters is obtained. In the second design stage, a partial list of available diameters is prepared based on the calculated optimal diameters, and the lengths for available diameters and pressure head of every lateral location along the manifold are calculated. The size of each of the pressure sections is determined according to the pressure head distribution along the manifold. Using the proposed methodology, the minimum manifold pipe cost is obtained, and the target emission uniformity is satisfied for gravity-fed drip irrigation subunits.