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Drip irrigation has the potential to conserve water and increase crop yields. However, existing drip irrigation systems often require high pumping power, making them financially inaccessible to smallholder farmers. Integrating a holistic system model with a cost-optimization scheme can enable the design and implementation of low-cost, solar-powered drip irrigations systems, ultimately making this technology more cost-effective for smallholder farmers. This paper describes the algorithms comprising an integrated model of solar-powered drip irrigation systems, consisting of agronomic, hydraulic, pump, and power system modules. It also introduces a preliminary optimization scheme for the power system, which uses the system hydraulics and pump curve to select an optimal solar array and energy storage configuration that minimizes capital cost. The system model and power system optimization is applied to three case studies, and the resulting power system configurations are compared to outputs from commercially-available software for sizing solar pumping systems. The results show that the model successfully captures the nuances in crop type, local weather patterns, and hydraulic system layout between different cases. This offers a greater level of flexibility than commercially available software, which tends to have broader applications and focuses on larger systems. Future model generations will add more variables to the optimization scheme — including pump selection, variable emitter flow rates and pipe geometries — to provide a versatile design tool for cost-optimized, solar-powered drip irrigation systems.

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A promising way of addressing the issue of growing water scarcity is through wider use of drip irrigation, which delivers water and fertilizer to crops in a slow, targeted manner, and has been shown to increase yields and water use efficiency. Yet, drip irrigation system adoption is low, primarily due to the high capital cost of the pressurized piping network and the pump, and operating energy cost. Lowering the water pressure needed for drip emitters to deliver water can reduce both capital and operating costs of drip systems. Here we present the results from field trials of new pressure-compensating online drip emitters that operate with a minimum compensating inlet pressure of 15 kPa (0.15 bar), in comparison to typical commercial emitters with minimum pressures of 50–100 kPa (0.5–1.0 bar). The field trials were carried out on nine farms in Morocco and Jordan over the course of one irrigation season with freshwater and treated wastewater. Low-pressure emitters are shown to reduce hydraulic energy per unit volume of water delivered by 43% on average compared to commercial emitters, without significantly sacrificing water emission uniformity (low-pressure emitters show uniformities of 81–91%, compared to 87–96% for commercial emitters). This energy reduction could lead to savings of 22–31% in the capital cost of a pump and emitters and the energy cost for a typical drip irrigation system. Thus, the low-pressure online emitters can be used as substitutes to commercial emitters that require higher water pressures, leading to reduced environmental impact and lower system costs.