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International audience; The need for lasting returns on the large investment in state-sponsored drip irrigation projects and the ambitious objectives aimed to achieve requires thorough and continuous assessment of the performance of irrigation systems in use. However, few studies have evaluated the performance of systems once they have been installed, leading to overestimation of actual drip irrigation performance. This study focuses on the Tadla Irrigation Scheme, where a 10 000-ha drip irrigation project had two objectives: improving water productivity and reducing pressure on groundwater resources. The results of the study show a satisfactory but progressively declining distribution uniformity at field level, after 3'4 years of functioning, pointing to potential dysfunction if the equipment is not renewed. The current over-irrigation of crops results in hefty water bills and debts of farmers, no water savings at the field scale, some savings at the scheme scale, but increased tension concerning water delivery. Farmers continued to use groundwater after converting to drip irrigation to avoid surface water shortage. The challenge is to ensure that groundwater is only tapped in exceptional cases to avoid overexploitation. The first step is ensuring more efficient irrigation practices, underlining the need for continuous performance assessment.

Drip irrigation is widely used in a range of different farming systems. Farmers generally adapt drip irrigation systems to their specific conditions. Irrigation performance is usually related to the hydraulic parameters of drip irrigation, and is usually expressed as a single static value. We developed a comprehensive approach to account for irrigation performance as a dynamic process, which evolves continuously due to changes in the way farmers schedule irrigation and renew irrigation equipment. The performance of drip irrigation systems used for greenhouse horticulture was evaluated in south-east Algeria in the 2012–2013 growing season. Two indicators were evaluated—distribution uniformity and water stress level. The approach was applied to 25 greenhouses owned by 13 farmers. Results revealed that the performance of drip irrigation systems is a dynamic process. We showed that farmers have integrated certain irrigation performance indicators such as distribution uniformity and water stress levels in their practices, as they have visible effects on crop production. Conversely, the relative irrigation supply does not directly interest the farmers, and was consequently not incorporated in their irrigation practices. We conclude that measuring drip irrigation performance must be accompanied by a broader understanding of the farming systems in which drip irrigation is used. (Resume d'auteur)

International audience; Modeling is one of the available tools to manage irrigation and to forecast crop yields. The purpose of this study was to adapt, calibrate, and validate the PILOTE model on globe artichokes (Cynara cardunculus var. scolymus L.) under drip irrigation in the Lower Cheliff Plain (Algeria) in two seasons (2011/2012 and 2012/2013) and to use it to predict soil water reserves and total biomass in other seasons (2006/2007, 2009/2010, and 2010/2011). The model uses daily climate data, soil characteristics, and plant data to simulate the leaf area index, total biomass, and soil water reserves during the crop growth cycle. Our results revealed a strong correlation between model outputs and observed data (leaf area index, soil water reserves, and plant biomass) in the calibration and validation years (coefficient of efficiency >0.90 and root mean square error

To help identify an irrigation system and irrigation strategy to improve durum wheat production in the context of water scarcity of Tunisia, the PILOTE (operative water balance and yield estimation) model and the RAIEOPT (furrow irrigation) model are coupled. The first step was to choose the most efficient surface irrigation system (SIS) with its irrigation strategy. On the basis of field experiment data, an economic-optimisation model allows the identification of the best SIS with its irrigation strategy for conditions of water scarcity in Tunisia. The furrow system with an inter-furrow spacing of 1.5 m and a strategy which consists on irrigating when the soil water reserve is 80% depleted are selected by the optimisation model. Using "deficit irrigation " principles which establish a ratio between the amount of water applied to a given crop and a economically acceptable target yield value, irrigation strategies for sprinkler and the selected SIS are identified. RAIEOPT-PILOTE coupling is used to perform this analysis for SIS. The results of the simulations, based on climatic data spanning the last 20 years, raise questions about the suitability of sprinkler irrigation method for clay soil conditions in Tunisia. This paper also aims to contribute to future economic studies that will take into account social constraints. This study should allow managers to choose between sprinkler irrigation methods and SIS modernisation.; Dans le but de proposer un systèmes d`irrigation avec sa stratégie d`usage visant à améliorer la production du blé dur dans le contexte de pénurie d`eau de la Tunisie, le modèle PILOTE (un modèle opérationnel estimant le bilan hydrique et le rendement) et le modèle RAIEOPT (modèle d`irrigation à la raie) sont couplés. Un premier volet de cet article traite du choix du système d`irrigation de surface (SIS) le plus efficient accompagné de sa stratégie de mise en oeuvre. L`irrigation à la raie avec un espacement de 1.5 m avec la stratégie consistant à irriguer lorsque la réserve en eau du sol est épuisée à 80% ont été sélectionnés par le modèle d`optimisation économique. Sur la base du concept '`irrigation déficitaire`` établissant un rapport entre la quantité d`eau apportée et un objectif de rendement économiquement acceptable, des stratégies d`irrigation pour l`aspersion et le SIS sélectionné sont identifiées. Le couplage des modèle RAIEOPT-PILOTE est utilisé pour réaliser cette analyse pour le cas du SIS. Les résultats de la simulation, basés sur une série climatique de 20 année, soulève la question relative à l`intérêt de l`aspersion dans le cas des sols argileux en Tunisie. Ce article peut être considéré comme une contribution à de futures études économiques devant tenir compte des contraintes sociales. Ce travail devrait permettre aux gestionnaires de choisir entre aspersion et modernisation de l`irrigation de surface.

The complexity of physical phenomena in furrow irrigation,where numerous parameters vary with time and space, makeempirical models more operative than mechanistic models forimproving irrigation efficiency. In addition, when theseempirical models are well adapted for real-time calibration onadvance trajectory, they can be considered an efficient toolto predict irrigation performance.In the first section of this paper, the selection of operativefurrow irrigation modelling for real-time applications isdiscussed. Models derived from Horton and linear infiltrationequations through the water balance equation (WBE) arepreferred to those derived from the 2-term Philip‘s equationand to the solution of WBE involving both the power advancefunction and Kostiakov‘s extended equation.The second section shows that simplified analytical modellingoptions can be added to the basic advance-infiltration modelfor improving irrigation efficiency. The modelling optiondeveloped in this paper concerns the prediction of cutoff timeand irrigation performance for closed-end furrows (CEF).The simplified analytical model for CEF based on the massconservation principle is successfully compared to field testsand numerical simulations.

The Gharb plain in Morocco suffers from water excess in winter and from water deficit during the spring and summer. This explains the low profitability of the investments in irrigation agreed by the Moroccan state and low yields of winter crops. Furrow irrigation systems may be a way to increase water productivity by improving the surface drainage in winter, and by irrigating the crops efficiently in spring and summer. The aim of this study was to assess the hydraulic performance of furrow systems and its agronomic impacts based on an experimental and a modelling approach. Yields were simulated for a series of 11 climatic years (1995–2006). Results clearly showed the advantage of the furrow system whatever the sowing dates. These results confirmed that to improve the water productivity of winter crops in the context of the Gharb scheme, attention has to be paid to surface drainage. Copyright © 2009 John Wiley & Sons, Ltd.