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Large-scale center pivots have been imported into Algeria since the 1980s to promote cereal production in the Sahara, but these pivots did not match either user needs or smallholder farming systems. In response, local artisans designed a smaller, cheaper, more robust center pivot in an incremental open innovation process that lasted 10 years. Currently, around 35 % of the Algerian potato production is irrigated by around 40,000 artisanal center pivots, each irrigating 1 ha. The aim of the study was to design and test an engineering approach to support local innovation actors in improving the performance of the artisanal irrigation pivot. Field observations and interviews were conducted with 24 users and 10 leading artisans to analyze the innovation process and judge which improvements would be acceptable. Experiments were then conducted in situ and in the national irrigation laboratory to analyze irrigation performance and test practical adjustments to improve it. Results showed that the distribution uniformity of pivots, less than 50 %, can be improved by adjusting the position of sprinklers along the pivot laterals and fine-tuning the nozzle aperture. This study opens new perspectives for engineering approaches to support user-led innovation.

Sanitary and environmental impacts, as well as effects on agricultural yields constitute important parameters to be taken into account in wastewater reuse projects, and depend on the treatment applied to the wastewater. Extensive treatments or irrigation with untreated wastewater are rarely studied, although they represent a significant share of unplanned or indirect wastewater reuse in the world. The aim of this study was to contribute to the evaluation of chemical properties of soil, crop yields, and the fate of fecal indicators in soil and plants when vegetable crops (lettuces and leeks) are irrigated by drip-irrigation using untreated wastewater (UW), water reuse or treated wastewater by stabilization ponds (TW) and fresh water (FW). Over two years (2018 and 2019), three lettuces (Lactuca sativa) and two leeks (Allium porrum) growth cycles were performed in a greenhouse, and soil analyses show increases in electrical conductivity (EC), chlorine (Cl), sodium (Na) and nitrate nitrogen concentrations (NO3) when TW and UW irrigation methods were compared to FW. As a result, FW irrigation and conventional fertilization lead to lower lettuce yields compared to TW (between 43 to 85% lower yields depending on the cultivation period) (p-value < 0.05). However, trends are not clear for UW. Leeks irrigated with FW have also a smaller fresh mass compared to TW and UW (around 35 % and 45 % differences in the median for UW and TW, respectively, p-value < 0.05), which shows a possible positive effect of continuous nutrient supply against the risks associated with higher water conductivity. In addition, in the soil, the irrigation with TW and with UW increases some concentrations, especially EC, mainly due to Cl and Na values. Fecal indicators increased from 1 to 2 log with the used of UW but the decay of fecal indicators in topsoils was slow (less than 1 log for enterococcus load after 6h), as shown by culture-based and molecular techniques (qPCR, droplet digital PCR). Fecal indicators were found in plants irrigated with untreated wastewater.

ABSTRACT Computational fluid dynamics (CFD) techniques have become an important tool for investigating and predicting flow behavior in many industrial and engineering processes. In the last two decades, CFD has been used for the study, design, and improvement of irrigation equipment. Numerical simulations can be used to predict fluid flow, heat transfer, and chemical reactions within complex systems. The objective of this review is to provide an overview of the uses of CFD in irrigation engineering applications. The paper is organized into two main sections: fundamentals of CFD and irrigation engineering applications. The first section presents the main methods used in numerical simulations, basic equations to predict fluid flow parameters, meshing concerns, and convergence criteria. In the second section, we present applications related to friction and local head losses in pipes, liquid and solid-liquid flow simulation in drippers, chemical scaling, filters, sprinklers, direct-acting pressure-regulating valves, and Venturi injectors. The briefly described applications indicated that CFD modeling can be an accurate, quick, and feasible method for the investigation of flow parameters in irrigation pipes, fittings, emitters, and accessories. The CFD simulations can be useful for designing new products as well as for improving and optimizing existing products. Computational fluid dynamics uses in irrigation engineering must be encouraged, particularly for innovation purposes resulting from the cooperation between academia and irrigation companies.

Emitter clogging is a major problem in microirrigation systems, which may result from the isolated or combined effects of physical, chemical, and biological agents. Clogging caused by suspended solid particles is the most common plugging form of emitters. Water quality and emitter geometry are key aspects in clogging processes. Any suitable test procedure to assess the sensitivity of drippers to clogging should take into account the predominant factors that influence clogging and must reproduce the field conditions. This research set out to assess the performance and suitability of a laboratory clogging test procedure in order to validate a methodology and to provide scientific results that may support the standardization of a clogging test method. The evaluated methodology has been used by the IRSTEA laboratory since 1974 (Platform of Research and experiment on Science and Technology for Irrigation - PReSTI, formerly LERMI) and its contents are currently being discussed by the ISO TC23/SC18 committee. The aim is to define a standardized testing protocol to evaluate the sensitivity of emitters to clogging due to solid particles. Replications analyzing the clogging resistance of four models of emitting pipes were carried out in a laboratory. The clogging test procedure enabled an accurate assessment of the combinations of concentration and size of particles that caused clogging in each model of dripper. However, a significant variability in degree of clogging was identified when the results of replications for each model of dripper were compared. Several requirements, concerns, and improvements related to the clogging test protocol were discussed.