Wastewater reuse in the Mediterranean region: Case of Morocco

10 p.International audienceThe southern Mediterranean region being one of the most dry and water scarce regions in the world. It is also expected that by 2025, due to population increase, the regional average water availability is projected to be just less than 500 cubic meters per person per year. Many countries in the region are mining groundwater, a temporary and risky expedient. The extended reuse of reclaimed (treated) wastewater could contribute considerably to the reduction of 'water stress' and 'water scarcity' in the Mediterranean countries as part of an Integrated Water Resources Management (IWRM) approach, focusing on the component wastewater reuse for irrigation and other purposes. The present article deals with the experiences carried out in Morocco in this domain. In spite of the progress that has been achieved in the last decade on technical, institutional, financial and legislative levels as regards the development of the process "sewage network-treatment-re-use", obstacles still hinder the deployment of the re-use of treated wastewater. In the current state of affairs, no project integrating the three components has been realized. This paradoxical situation is due to several constraints

Integrated management tool for water, crop, soil and N-fertilizers: the Saltmed model

Good management will be required to double food production by 2050. Testing management strategies is commonly carried out in the field. Such trials are costly and require quite a long time to produce consistent and reliable results. An alternative option to field trials would be the use of tested models. Models can run with ‘what-if’ scenarios depicting different types of field management. They are a less costly and faster alternative to field trials. In contrast to some existing models, the SALTMED 2013 model is designed for general applications that include various irrigation systems and water application strategies, water of different qualities, variety of crops and trees, different nitrogen based fertilizers and different soil types. The model can simulate up to 20 fields with different treatments, different crops, different irrigation systems and management as well as different N-fertilizer applications. The SALTMED model has been tested using field experiment data from Portugal, Italy, Denmark, Morocco, Egypt, Syria, Brazil and Iran. It successfully simulated soil moisture, salinity, nitrogen content, grain yield and total dry matter. The model provides academics, professionals and extension services with a management tool for crops, soil, water and nitrogen fertilizers. This paper describes the processes, the equations of the model and summarizes the different applications and results obtained

The effect of saline irrigation water on the yield of pepper: experimental and modelling study

The present study investigates the impact of using saline water on pepper crop yield and the application of a numerical model in predicting soil moisture and relative yield under saline irrigation conditions. In the greenhouse experimental study conducted in Antalya, Turkey, the effects of different irrigation regimes with salinity treatments using a drip irrigation system were investigated for two pepper varieties. The irrigation regimes consisted of four irrigation treatments with four salinity levels in two cropping seasons—spring 2011 and autumn 2011. The numerical model SALTMED was used and calibrated using measured soil moisture of a control experiment run during spring 2011. After the calibration, the model was validated using other experimental treatments during spring 2011 and all the experimental treatments in autumn 2011, with appropriate salinity stress parameter π50 values which are calibrated versus the highest salinity treatments in the spring 2011 and autumn 2011 experiments. The predicted results show the ability of the model to reproduce the measured soil moisture at three soil layers 0–20, 20–40 and 40–60 cm. The predicted relative yield results are in good agreement with measured data. Although the numerical model SALTMED has been used in several studies in the past, this is the first study that illustrates the potential capacity of the model for use in managing greenhouse production

SALTMED model as an integrated management tool for water, crop, soil and N-fertilizer water management strategies and productivity: field and simulation study

This paper is a follow-up from a paper which described the SALTMED model. In this paper the focus is on the model application,using data of tomato and potato from field experiments in Italy, Greece (Crete) and Serbia. Drip full irrigation, drip deficit irrigation, drip as partial root drying (PRD), sprinkler and furrow irrigation were used in the 3-yr experiment between 2006 and 2008. In drip-irrigated experiments, the drip line was 10–12 cm below the surface. Dry matter, final yield, soil moisture and soil nitrogen were successfully simulated. The study showed that there is a great potential for saving water when using subsurface drip, PRD or drip deficit irrigation compared with sprinkler and furrow irrigation. Depending on the crop and irrigation system, the amount of fresh water that can be saved could vary between 14 and 44%. PRD and deficit drip irrigation have proved to be the most efficient water application strategies with the highest water productivity

Using deficit irrigation with treated wastewater in the production of quinoa (Chenopodium quinoa Willd.) in Morocco | El uso de riego deficitario con aguas residuales tratadas en la producción de quinua (Chenopodium quinoa Willd.) en Marruecos

Scarcity of water resources and growing competition for water, reduce water availability for irrigation. In this experiment which was carried out in the south of Morocco, treated wastewater was used as an alternative resource for irrigation of quinoa (Chenopodium quinoa Willd.). During the first season (2010), six deficit irrigation treatments were applied during all crop stages on DO708 cultivar alternating water stress level at either 100 or 50% of ETm (maximal evatranspiration), while during the second season (2011), three deficit irrigation treatments 100, 50 and 25% were applied only during vegetative growth stage on two quinoa cultivars DO708 and QM1113. The highest water productivity was obtained when deficit irrigation was applied during the vegetative growth stage. Applying 50% of ETm during first season and second season resulted in highest yield. The most sensitive growth stage of quinoa to drought stress was the seed filling stage, and during this stage it is recommended to supply water to avoid yield and water productivity decrease. Combining deficit irrigation strategy, engineering solution (modernization of the irrigation systems, soil moisture monitoring), and the reuse of treated wastewater for irrigation, could improve water productivity of this drought tolerant crop under conditions of limited water resources. Key words: Drought stress, water productivity, leaf area index, salinity, yield RESUMEN La escasez de recursos hídricos y la creciente competencia por el agua reduce la disponibilidad de agua para el riego. En este experimento que se llevó a cabo en el sur de Marruecos, el agua residual tratada se utilizó como un recurso alternativo para el riego de quinua (Chenopodium quinoa Willd.). Durante la primera temporada (2010), se aplicaron seis tratamientos de riego deficitario alternando 100 y 50% de la ETm (evapotranspiración máxima) durante todas las etapas del cultivo en el cultivar DO708, mientras que en la segunda temporada (2011) se aplicaron tres tratamientos de riego deficitario 100, 50 y 25% sólo durante la etapa de crecimiento vegetativo en dos cultivares de quinua DO708 y QM1113. La mayor productividad del agua se obtuvo cuando se aplicó el riego deficitario durante la etapa de crecimiento vegetativo. Un tratamiento de riego deficitario con 50% de la ETm durante la primera y la segunda temporada registró la mayor productividad del agua. La etapa de crecimiento más sensible de la quinua al estrés hídrico fue la etapa de llenado de la semilla y durante esta etapa se recomienda el suministro de agua para evitar la disminución del rendimiento y reducir la productividad del agua. La combinación de la estrategia de riego deficitario, solución de ingeniería (modernización del sistema de riego, sensores de humedad del suelo) y la reutilización de aguas residuales tratadas para el riego, podría mejorar la productividad del agua de este cultivo tolerante a la sequía bajo condiciones de los recursos hídricos limitados. Palabras clave: Estrés hídrico, productividad del agua, índice de área foliar, salinidad, rendimient

Applying partial root drying drip irrigation in the presence of organic mulching. Is that the best irrigation practice for arid regions? Field and modelling study using the saltmed model

This research aimed at investigating the impact of irrigation systems, a deficit irrigation strategy and organic mulching using rice straw on maize water productivity in Egypt's arid conditions. The field experiment included 16 treatments over 2 seasons, 2015 and 2016. Irrigation systems were a drip irrigation system (DIS) and a furrow irrigation system (FIS), while the irrigation strategies were 100% full irrigation (FI), 75% FI, 50% FI and partial root drying (PRD). Organic mulching using rice straw (OMRS) was also investigated. The experimental results indicated that there was a positive impact of applying a PRD strategy by drip irrigation in the presence of organic mulching on the yield (12.6 t ha‐1 for 2015 and 12 t ha‐1 for 2016) and on the water productivity of maize (4.81 kg m‐3 for 2015 and 4.58 kg m‐3 for 2016), but under the control treatment (FIS with 100% full irrigation and without organic mulching) yield was 7.22 t ha‐1 for 2015 and 7.34 t ha‐1 for 2016 and water productivity of maize was 0.64 kg m‐3 for 2015 and 0.62 kg m‐3 for 2016. The SALTMED model simulated reasonably well the soil moisture and salinity distribution as well as maize dry matter, yield and water productivity for all treatments, with R2 of 0.998, 0.997 and 0.996, respectively. The results support the use of a PRD strategy by a drip irrigation system accompanied by an organic mulch of rice straw instead of the commonly used furrow irrigation. The PRD would save more fresh water, achieve higher yields and water productivity. In addition, mulching would reduce evaporation losses, retain soil moisture and increase organic matter content

Improving water resources management using different irrigation strategies and water qualities: Field and modelling study

The aim of this study was to investigate the effects of two different irrigation strategies, regulated deficit irrigation, RDI and partial root drying, PRD using surface freshwater (SW) and brackish treated wastewater (TWW) for maize and potato crops. The SALTMED model has been applied using the field measurements of two cropping seasons 2013 and 2014 at the Canale Emiliano Romagnolo, CER’s experimental farm located in Mezzolara di Budrio (Bologna, Italy). In 2013, PRD irrigated potato received 17% less irrigation water than RDI but produced nearly the same yield as under RDI. The water productivity, o naverage, was 11% higher for PRD compared with RDI. For maize 2014 season, the PRD strategy received almost 15% less irrigation water, but produced a yield only 6% lower than that of RDI and gave equal water productivity to RDI. Given that the two strategies received the same amount of rainfall the results favour the PRD over RDI. Had the site not received above average rainfall (258 mm in 2013 and 259 mm during the 2014 growing seasons), PRD might have produced higher yield and water productivity than RDI. In terms of model simulations, overall, the model showed a strong relationship between the observed and the simulated soil moisture and salinity profiles, total dry mater and final yields. This illustrates SALTMED model’s ability to simulate the dry matter and yield of C3 and C4 crops as well as to simulated different water qualities and different water application strategies. Therefore, the model can run with “what if” scenarios depicting several water qualities, crops and irrigation systems and strategies without the need to try them all in the field. This will reduce costs of labour and investment

Utilisation de l'irrigation déficitaire avec des eaux usées traitées pour améliorer la productivité des cultures du maïs sucré, pois chiche, féverole et quinoa

Several experiments were conducted in the south of Morocco (IAV-CHA, Agadir) during two seasons 2010 and 2011 in order to evaluate the effect of deficit irrigation with treated wastewater on several crops (quinoa, sweet corn, faba bean and chickpeas).  During the first season (2010) three crops were tested, quinoa, chickpeas and sweet corn applying 6 deficit irrigation treatments during all crop stages alternating 100% of full irrigation as non-stress condition and 50% of full irrigation as water deficit condition applied during vegetative growth, flowering and grain filling stage. For all crops, the highest water productivity and yield were obtained when deficit irrigation was applied during the vegetative growth stage. During the second season (2011) two cultivars of quinoa, faba bean and sweet corn have been cultivated applying 6 deficit irrigation treatments (rainfed, 0, 25, 50, 75 and 100% of full irrigation) only during the vegetative growth stage, while in the rest of crop cycle full irrigation was provided except for rainfed treatment. For quinoa and faba bean, treatment receiving 50% of full irrigation during vegetative growth stage recorded the highest yield and water productivity, while for sweet corn applying 75% of full irrigation was the optimal treatment in terms of yield and water productivity.Plusieurs essais ont été conduits dans le sud du Maroc (IAV-CHA, Agadir) durant deux saisons 2010 et 2011 dont le but d’évaluer l’effet de l’irrigation déficitaire par les eaux usées traitées sur plusieurs cultures (quinoa, maïs doux, fève et pois chiche). Durant la première saison (2010) trois cultures ont été testées, quinoa, maïs doux et pois chiche en appliquant 6 traitements d’irrigation déficitaire durant tout les stades culturaux en alternant 100% d’ETm comme condition de confort hydrique et 50% d’ETm comme conditions de stress durant le stade de croissance végétative, floraison et remplissage des grains. Pour toutes les cultures, le rendement et la productivité d’eau les plus élevés ont été obtenus lorsque l’irrigation déficitaire a été appliquée durant le stade de croissance végétative. Pendant la deuxième saison (2011) deux lignés du quinoa, la fève et le maïs doux ont été cultivées en adoptant 6 traitements d’irrigation déficitaire (bour, 0, 25, 50, 75 et 100 d’ETm) appliqués juste pendant le stade de croissance végétative, tandis que durant le reste du cycle cultural les cultures ont reçues une irrigation complète sauf pour le traitement bour. Pour le quinoa et la fève, appliquant 50% d’ETm durant le stade végétatif a permis d’obtenir le rendement et la productivité d’eau les plus élevés, tandis que pour le maïs doux le traitement optimal qui a enregistré le rendement et la productivité d’eau les plus élevés est celui qui a reçu 75% d’ETm.&nbsp