Showing papers in "Irrigation and Drainage in 2015"

The Effect of Saline Irrigation Water on the Yield of Pepper: Experimental and Modelling Study

Abstract: 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. Copyright © 2015 John Wiley & Sons, Ltd.

Integrated Management Tool for Water, Crop, Soil and N-Fertilizers: The Saltmed Model†

Abstract: 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.

Response of Quinoa to Different Water Management Strategies: Field Experiments and Saltmed Model Application Results

Abstract: Given the current water shortage in North Africa, improving water management to produce more crop per drop is vital. In addition, the introduction of drought-tolerant, less water-consuming crops such as quinoa is of great interest. To understand the response of quinoa to water stress in terms of biomass and grain yield under various irrigation management strategies, the SALTMED model was employed using field measurements during the cropping seasons of 2011 and 2012 at a site in the Marrakech region, south Morocco. Quinoa showed its ability to grow in the south of Morocco and give a good yield under full irrigation. However, the experimental and modelling results showed that under rainfed and deficit irrigation, the grain yield was lower than under the full irrigation treatment and was dependent on water deficit level. The study revealed that a reasonable grain yield of quinoa can only be obtained if it was subjected to moderate water stress conditions. The results indicated that the SALTMED model is able to simulate the quinoa biomass and grain yield under various water deficit levels and that the model can be used in the evaluation of different irrigation strategies.

Groundwater Recharge and Capillary Rise in Irrigated Areas of the Upper Yellow River Basin Assessed by an Agro‐Hydrological Model

Abstract: Groundwater recharge and capillary rise are key factors in water balance and management studies carried out in irrigated areas with shallow groundwater tables. In this study, the mathematical model SWAP-EPIC was applied to analyse the processes of groundwater recharge and capillary rise in the Hetao Irrigation District of the upper Yellow River basin. The model was calibrated and validated using non-weighing lysimeter data collected in 2007 and 2008, respectively. Simulations of soil water content, groundwater depth, leaf area index and yield fitted well with observations. The calibrated model was further used to analyse the response changes of groundwater recharge and capillary rise under different groundwater depth scenarios. Results indicated that capillary rise rate increased as crop roots developed, averaging 2.3 mm d−1 during the mid-stage while groundwater was set at 100 cm depth. Groundwater contribution to crop growth was significant when the depth of the groundwater table was less than 150 cm, but was irrelevant for depths over 200 cm. Despite similar amounts of water being applied in each irrigation event, groundwater recharge varied significantly, resulting in recharge coefficients that varied from zero to 0.59. The amount of rainfall occurring previous to an irrigation event, lower evapotranspiration rates and shallower groundwater table depths resulted in higher antecedent soil moistures during an irrigation event and subsequently more effective groundwater recharge. The analysis of groundwater recharge and capillary rise processes will be useful in increasing field irrigation efficiency, improving the accuracy of groundwater modelling by reducing uncertainties, and making relevant management decisions in Hetao. Copyright © 2015 John Wiley & Sons, Ltd.

Adoption of Small-Scale Irrigation and Its Livelihood Impacts in Northern Ethiopia

Abstract: The potential of smallholder-irrigated agriculture to enhance food security and improve livelihoods has led the government of Ethiopia to invest significantly in irrigation establishment. This article aims to investigate the impact of small-scale irrigation on households' livelihood. To deal with the problems of purposive targeting and self-selection which are likely to occur for this type of intervention, we use a sophisticated econometric technique called ‘propensity score matching’ to study this impact. Our findings confirm the presence of a statistically significant difference in income, overall expenditure, asset accumulation and expenditures on agricultural inputs between the treated and control households. In contrast, no statistically significant differences in livestock resources, food consumption, and expenditure on education and health were found. Furthermore, the proportion of poor is respectively 20 and 30% for the treated and control households. So, overall it can be concluded that participation in the small-scale irrigation has robust and positive effect on most of the livelihood indices and that an expansion of irrigation schemes is a good strategy in the water-stressed and drought-prone areas of Ethiopia. Copyright © 2015 John Wiley & Sons, Ltd.

Assessing Hydrus‐2D to Simulate Soil Water Content (SWC) and Salt Accumulation Under an SDI System: Application to a Potato Crop in a Semi‐Arid Area of Central Tunisia

Abstract: In this paper the suitability of the HYDRUS-2D model to simulate volumetric soil water content in the root zone of a potato crop under subsurface drip irrigation (SDI) is initially assessed on the basis of a field study. Then, considering that the crop is moderately sensitive to soil salinity, the model is tested to predict the salt distribution around a buried emitter, when two different water qualities (i.e. electrical conductivity of 1.0 and 4.0 dS m-1) are used during the growing season (treatments T1 and T2). Finally, the soil volume in which salt accumulates is distinguished by the model for the two treatments, for which the respective yields are not significantly different. The results showed that in the root zone, simulated and measured soil water content (SWC) are fairly close. HYDRUS-2D well enough predicts the average salt concentration in the soil and evaluates the dynamic of mass-conservative solutes around buried emitters. In both treatments, the salt concentration resulted in an increase in the wetting bulb, with a maximum located towards the edge of the wetting bulb and near the soil surface. Copyright © 2015 John Wiley & Sons, Ltd. Resume Dans cet article, HYDRUS-2D a ete utilise pour l'estimation de la teneur en eau volumique dans la zone racinaire d'une culture de pomme de terre, irriguee au goutte a goutte enterre dans les conditions climatiques tunisiennes. Le modele a ete utilise pour l'estimation de la distribution du sel autour du goutteur enterre pour deux qualites differentes d'eau caracterisees par des conductivites electriques egales a 1.0 et 4.0 dS m-1, respectivement (traitements T1 et T2). Le modele permet de predire le volume du sol dans lequel les sels s'accumulent. Selon le test Student (t), les valeurs de la teneur en eau volumique du sol dans la zone racinaire qui sont prevues par HYDRUS-2D sont significativement correlees aux valeurs reelles mesurees en T1 et T2. Les resultats ont egalement mis en evidence que le modele est capable d'estimer la concentration moyenne de sel dans le sol et d'evaluer la dynamique des solutes a conservation de masse autour d'un goutteur enterre. En outre, dans les deux traitements, la concentration de sel augmente a l'interieur du bulbe, avec un maximum de concentration de sel situee dans le front d'humectation et a proximite de la surface du sol. La concentration de sel dans T2 est legerement plus elevee que dans T1. Cependant, la salinite de l'eau legerement elevee utilisee pour l'irrigation n'a pas affecte significativement la transpiration reelle de la pomme de terre et par consequent son rendement. Copyright © 2015 John Wiley & Sons, Ltd.

Performance Assessment Of Collective Irrigation In Water Users’ Associations Of Calabria (Southern Italy)

Abstract: In order to identify the weakness factors of the collective irrigation service, the system operation and financial performance of seven Water Users' Associations (WUAs) in Calabria was quantitatively evaluated by a limited set of indicators and compared by common benchmarking techniques. In relation to the surveyed system operation indicators, the investigation highlighted a satisfactory fulfilment of crop water demand, but a very low efficiency in exploiting the available irrigation water in all the investigated WUAs. Concerning the financial aspects of the irrigation service, the results indicated a very low degree of financial self-sufficiency of the WUAs, a high variability of management, operation and maintenance costs and personnel requirements referred to the irrigated area unit and a very wide range of average water price per hectare. The application of principal component analysis provided three derivative indicators, measuring the operative and economic performance of the WUAs. The clustering algorithms and calculation of the quality index showed respectively similarities among the irrigation service performance of the investigated WUAs and allowed the ranking of these collective agencies. Copyright © 2015 John Wiley & Sons, Ltd.

Irrigation in Southern Africa: Success or Failure?

Abstract: Despite widespread recognition of the importance of irrigation development in southern Africa, no comprehensive examination exists on the performance of past irrigation schemes in the region This paper systematically examines existing literature on irrigation schemes in southern Africa in order to: (i) determine the proportion that can be considered successful; and (ii) identify and rank factors that explain variation in performance The results indicate that some 59% of irrigation schemes in southern Africa can be considered successful Factors associated with successful performance include: management style, irrigation method, crop mix, type of financier and geography The levels of success identified through this review validate calls to increase the irrigated area in southern Africa These results nonetheless highlight opportunities to strengthen the way in which future irrigation schemes are undertaken In particular, these results may call for increased use of sprinkler irrigation and reduced use of flood irrigation with pumping The results also suggest more investment could be channelled into schemes focused on maize–vegetable crop rotations and sugar cane, and caution applied to government management of schemes Copyright © 2015 John Wiley & Sons, Ltd

SALTMED Model as an Integrated Management Tool for Water, Crop, Soil and N‐Fertilizer Water Management Strategies and Productivity: Field and Simulation Study

Abstract: 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.

Assessing Amaranth Adaptability in a Mediterranean Area of South Italy under Different Climatic Scenarios

Abstract: The aim of the present work was to study the adaptability of amaranth in a typical Mediterranean environment of South Italy under changing climate scenarios. In a first stage, experimental data from a field trial conducted during 2009–2010 on the Volturno River Plain (Italy) with grain amaranth grown under different irrigation strategies, were used to define the thermal requirements and the yield response function to soil water availability of amaranth. The observed soil moisture data were used to calculate the relative soil water deficit (RSWD) index and seed yield data were expressed as relative yield (Yr). Yr and RSWD calculated data were then graphically correlated to obtain the amaranth yield response function to soil water availability. In a second stage the SALTMED model was used to simulate impacts of present, past and future climate scenarios on amaranth growth cycle and yield. Climate-change scenarios (Special Report on Emission Scenarios A1B, A2 and B1) data, used as input in the model, were derived from six global circulation models using a weather generator. The results showed that in a changing climate, temperature affects the relative duration of the growth cycle and could be a critical determinant of grain yield. The use of supplemental irrigations could allow the amaranth to guarantee a high seed yield under Mediterranean conditions.

Emitter Uniformity and Application Efficiency for Centre‐ Pivot Irrigation Systems

Abstract: A significant portion of the intensively cultivated agricultural areas in the Southern Great Plains of the USA is located in the Texas High Plains. Agriculture in this region mainly depends on water from the vast underground Ogallala Aquifer. Due to excess withdrawal and a slow recharge process, groundwater levels are declining in many areas of the aquifer. Recently, regulations have been enacted in the Texas High Plains for restricting the amount of water pumped from the Ogallala Aquifer. In addition to pumping restrictions, conserving water by promoting irrigation systems with high application efficiency is also a priority. We investigated the emitted uniformity and application efficiency of 14 centre-pivot irrigation systems in the Texas High Plains. Application efficiencies were in the range of 60–70% for mid-elevation spray application (MESA) systems, 70–80% for low-elevation spray application (LESA) systems, and greater than 90% for low-energy precision application (LEPA) systems. Correction of the small number of defective emitters per system would not realize significant water savings. However, water savings could be realized by switching fromMESA or LESA to LEPA, assuming the choice of crop allowed it. Copyright © 2015 JohnWiley & Sons, Ltd. key words: irrigation auditing; emitter uniformity; application efficiency; mid-elevation spray application; low elevation spray application; low-energy precision application Received 29 April 2014; Revised 29 July 2014; Accepted 29 July 2014

Parameterization and Field Validation of Saltmed Model for Grain Amaranth Tested in South Italy

Abstract: Grain amaranth is an underutilized Andean crop characterized by interesting agronomic and qualitative traits and could represent an important food source in areas with salinity and drought problems like the Mediterranean region. Knowledge of crop growth parameters allows us to parameterize simulation models that are useful tools to study the adaptability of a crop to different environmental and management conditions. In this study, the SALTMED model has been parameterized, calibrated and evaluated for grain amaranth under Mediterranean conditions, with data from a field trial conducted during 2009–2010 in South Italy. The model evaluation was made using seed yield, dry matter and soil moisture data of amaranth irrigated with saline and fresh water. The simulation results showed a high degree of precision of SALTMED in the simulation of the hydrological processes at different soil depths, crop yield and dry matter under different agricultural practices. SALTMED can be used as a useful tool to optimize grain amaranth production in the Mediterranean region.

Effects of Superabsorbent Polymers on Infiltration and Evaporation of Soil Moisture Under Point Source Drip Irrigation

Abstract: The application of superabsorbent polymers (SAPs) in agriculture can enhance water use efficiency and ease water shortage in agriculture. In this study, by applying SAPs to the middle layer of the soil root zone, the effects of SAPs on moisture distribution during infiltration and evaporation under the condition of point source irrigation were investigated. The results show that during infiltration, the wetting front formed an accident change zone in the horizontal direction; in the bottom layer, the horizontal infiltration rate is greater than the vertical infiltration rate due to the effect of SAPs from the middle layer; the soil water content in the middle layer increased remarkably by 23.6%, higher than that in the surface and bottom layers; during evaporation, the soil water content changed significantly in the surface layer due to strong evaporation on the surface, it was largest and quite even in the SAP–soil mixture layer, and decreased the least in the bottom layer due to water storage in the mixture layer. Therefore, SAP application in the crop root layer is helpful to conserve soil water content in the crop root zone, inhibit evaporation of soil water in the lower layer and facilitate moisture conservation. Copyright © 2015 John Wiley & Sons, Ltd. Resume L'application de polymeres super-absorbants (SAP) dans l'agriculture peut ameliorer l'utilisation de l'eau et faciliter la gestion de la penurie d'eau dans l'agriculture. Nous avons etudie les incidences d'un SAP applique sur la couche mediane de la zone racinaire d'un sol sur l'evaporation et l'infiltration au droit d'un goutteur d'irrigation. Les resultats montrent que lors de l'infiltration, le front d'humectation subit un accident dans le sens horizontal; dans la couche inferieure, le taux d'infiltration horizontal est superieur a la vitesse d'infiltration verticale sous l'effet du SAP de la couche centrale; la teneur en eau du sol dans la couche intermediaire a augmente de 23.6%, superieure a celle de la surface et des couches inferieures; au cours de l'evaporation, la teneur en eau du sol a change de maniere significative dans la couche de surface en raison d' une forte evaporation; la variation a ete la plus importante dans la couche de melange SAP–sol, et la diminution de teneur en eau a ete la plus petite dans la couche inferieure en raison du stockage d'eau dans la couche avec SAP. Par consequent, l'application de SAP dans la zone racinaire est utile a y conserver l'humidite du sol et a inhiber l'evaporation de l'eau dans la couche inferieure. Copyright © 2015 John Wiley & Sons, Ltd.

Reclaimed Water Filtration Efficiency and Drip Irrigation Emitter Performance with Different Combinations of Sand and Disc Filters

Abstract: Filters are the most important components in micro-irrigation systems, in particular for filtering high levels of suspended solids in reclaimed water An experiment was conducted using reclaimed water to evaluate the removal efficiencies of sand filters with different uniformity coefficients (UCS) and in combination with sand filters with a 130 µm disc filter (120-mesh) The treatment effects on emitter discharge were also investigated in this study The results showed that the sand filters exhibited removal efficiencies of 114–480%, increasing to 307–803% when combined with the disc filter The sand filter removal efficiency decreased with increase of the media diameter A linear-plateau relationship was observed between the removal efficiency and UCS Compared to the control group, the combined filters reduced emitter clogging and significantly prevented a decrease in emitter discharge It is suggested using the equivalent diameter, dt, to represent the filter medium diameter instead of using the effective diameter, de The recommended value for the sand filter UCS > 20 for a mean total suspended solids (TSS) of 175 ± 127 mg l−1 Copyright © 2015 John Wiley & Sons, Ltd

Optimal Irrigation Scheduling, Irrigation Control and Drip Line Layout to Increase Water Productivity and Profit in Subsurface Drip‐Irrigated Agriculture

Abstract: A new optimization framework is presented which is able to identify optimal solutions for maximum profit design of subsurface drip irrigation (SDI) systems under limited supply. To solve this complex optimization problem, decomposition is used which splits the problem into three sub-problems: (i) optimal irrigation control, which maximizes water distribution uniformity and minimizes percolation losses; (ii) optimal irrigation scheduling, which minimizes irrigation water applied in order to meet a high yield with a specified reliability; and (iii) optimal drip line layout, which includes the solutions of the other sub-problems and maximizes profitability. The multi-level optimization framework was tested in France with corn cultivated on two SDI plots with drip line spacing of 1.2 m (SDI120) and 1.6 m (SDI160), respectively. HYDRUS simulations estimated adequate irrigation amounts of 20–35 mm per event. For optimal irrigation scheduling, initial schedules were provided at sowing and adapted weekly according to observed weather data and synthetic weather scenarios. The presented framework significantly increased profit and water productivity for deficit SDI designs. The latter was increased up to 30% (SDI120), compared to seven other irrigation experiments. The optimal SDI design was achieved by SDI160, which increased profitability by 27% compared to SDI120. Copyright © 2015 John Wiley & Sons, Ltd.

Comparison of Drip‐ and Furrow‐Irrigated red Pepper Yield, Yield Components, Quality and net Profit Generation

Abstract: The effects of different irrigation regimes on yield and quality and net profit of processing red pepper irrigated with drip and furrow irrigation systems under field conditions in the Mediterranean region of Turkey were evaluated over two years. The treatments for drip consist of full irrigation (DFI), deficit irrigation DDI‐75, D‐PRD‐50, DF‐PRD‐50 and DDI‐50, and for furrow: full irrigation (FFI), fixed alternative furrow (FAF‐50) and PRD furrow (FPRD‐50). FAF‐50 and FPRD‐50 received 50% of water applied to FFI. In FAF‐50 the same furrows were irrigated while FPRD‐50 was irrigated alternately. Irrigation methods and levels had a significant effect on total yield and some quality parameters of red pepper. Drip produced higher red pepper yields than furrow. The highest yield in the drip system was obtained from the DFI treatment followed by DDI‐75, DDI‐50 and DF‐PRD‐50 treatments. Although D‐PRD‐50, DF‐PRD‐50 and DDI‐50 received the same amount of water, D‐PRD‐50 resulted in a higher yield. In furrow treatments, FFI resulted in the highest yield, followed by FPRD‐50 and FAF‐50. Water productivity (WP) decreased with increasing water quantity for both irrigation systems. Fruit weight, size and flesh thickness were higher in the DFI and FFI treatments. Full irrigation treatments (DFI and FFI) generated the highest net income.

Application of Reinforcement Learning Algorithm for Automation of Canal Structures

Abstract: Automation is a main option for improving the flexibility of irrigation canals. Control systems are required for this task. The main element of the control systems is a control algorithm. There are different control algorithms which have been developed. Investigation of the developed algorithms showed they have some limitations in terms of accuracy and time. These limitations make the researchers develop and introduce new and better control algorithms. Reinforcement learning (RL), which is a branch of artificial intelligence systems, is a powerful control algorithm successfully applied in robot control and in industry. In this research, a mathematical model of the RL algorithm was developed to control water depth upstream of check structures. RL learns the map of water depth-check structures adjustment by maximizing a reward function. To test the RL algorithm, a mathematical model of a flume was used. Different scenarios of inflow increase and decrease were simulated. System response time (SRT), maximum absolute error (MAE), and integral of absolute magnitude of error (IAE) indicators were used to evaluate RL. Results were obtained and analysed. Low depth variations and performance indicators were shown. The maximum values of SRT, MAE and IAE were obtained as 252 s, 3.07% and 0.152%, respectively. Results showed the RL algorithm is a beneficial control system and can be applied in irrigation canals. Copyright © 2015 John Wiley & Sons, Ltd. RESUME L'automatisation est une option principale pour ameliorer la flexibilite des canaux d'irrigation. Elle requiert des systemes de controle. L'element principal de ces systemes de commande est un algorithme de controle. Il existe differents algorithmes de controle; apres enquete, il apparait qu'ils ont tous des limitations en termes de precision et de temps, ce qui implique d'en rechercher de nouveaux et de meilleurs. L'apprentissage par renforcement (RL), qui est une branche des systemes d'intelligence artificielle, est un algorithme de controle puissant applique avec succes dans le controle de robots et dans l'industrie. Dans cette recherche, le modele mathematique du RL a ete concu pour controler la profondeur de l'eau en amont des ouvrages de controle. Le RL apprend la carte de l'ajustement des profondeurs d'eau aux ouvrages de controle en maximisant une fonction de recompense. Le RL a ete teste avec un modele mathematique de deversoir. Differents scenarios d'augmentation et de diminution ont ete essayes. Le temps de reponse du systeme (SRT), l'erreur maximale absolue (MAE), l'integrale de la magnitude de l'erreur absolue maximale (IAE) sont les indicateurs utilises pour evaluer le RL. Les resultats ont ete obtenus et analyses. Il y a eu peu de variations de profondeur et d'indicateurs de performance. Les valeurs maximales de SRT, MAE, et d'IAE ont ete 252 s, 3.07% et 0.152%, respectivement. Les resultats ont montre que le RL est un systeme de commande benefique et peut etre applique dans les canaux d'irrigation.

Environmental benefits of improved water and nitrogen management in irrigated sugar cane: A combined crop modelling and life cycle assessment approach

Abstract: L'application d'eau d'irrigation et d'engrais azotes (N) en exces par rapport a la demande des cultures reduit la profitabilite et a de multiples impacts negatifs sur l'environnement. La dynamique de l'azote dans les agrosystemes est extremement complexe, et des modeles mecanistes de culture sont souvent necessaires pour quantifier l'impact de pratiques de gestion ameliorees sur la reduction des pertes en azote. Cette etude utilise la methodologie de l'Analyse du Cycle de Vie (ACV) combinee a la modelisation mecaniste pour quantifier les benefices environnementaux d'une gestion amelioree de l'eau et des fertilisants azotes par des producteurs de canne a sucre, dans une etude de cas a Pongola, Afrique du Sud. Nous avons compare un scenario de base representatif des pratiques courantes et intuitives des producteurs en termes d'irrigation, a deux scenarios supplementaires representant des pratiques de gestion plus rationnelles de l'eau, et de l'eau et des engrais, respectivement. Les resultats montrent qu'une meilleure gestion de l'eau et de l'azote peut generer une reduction de 20% de la consommation en energie non-renouvelable, avec des rendements maintenus voire ameliores. Les emissions totales de GES peuvent potentiellement etre reduites de 25%. La reduction des applications d'engrais, rendue possible par le moindre lessivage de l'azote sous irrigation raisonnee, resulte en de fortes reductions de ces deux categories d'impacts. La consommation totale en eau est similaire entre scenario de base et scenarios de meilleure gestion de l'eau; cependant l'utilisation de l'eau de pluie est plus efficiente avec les irrigations raisonnees, reduisant ainsi les besoins d'extraction de la ressource. Par la prise en compte simultanee d'impacts environnementaux multiples, la combinaison de l'ACV et de la modelisation mecaniste de culture montre un potentiel pour identifier les pratiques ameliorees et pour developper un accompagnement en eco-conception de systemes. (Resume d'auteur)

Analysis of Evaluation Indicators for Furrow Irrigation Using Opportunity Time

Abstract: Evaluation procedures have been developed for effective design and management of irrigation systems Furrow irrigation is one of the main types of applying water in the field In the present study, a new procedure for field evaluation of water distribution in furrow irrigation is proposed For this purpose, application efficiency (Ea), water requirement efficiency (Er), deep percolation (DP) and tail water ratio (TWR) have been introduced, based on the average of dimensionless infiltrated depth values in the four data groups The relationships between coefficient of uniformity CU and distribution uniformity DU have been described by opportunity time values of each quarter and using the linear equation instead of the infiltration function The proposed procedure was compared to existing methods by nine irrigation scenarios including three furrow length and three inflow rates The results show that the evaluation indicators of furrow irrigation calculated with non-dimensional parameters depend on opportunity time and new coefficients of the linear infiltration equation Also, there was no observed significant difference on the suggested indice values and classical performance indicators Copyright © 2015 John Wiley & Sons, Ltd

Evaluation of Groundwater Suitability for Irrigation in the Araniar River Basin, South India—A Case Study Using Gis Approach

Abstract: Spatial and temporal variations in the groundwater quality of the Araniar River Basin, south India, were studied to determine its suitability for irrigation through development of irrigation water quality index (IWQI) maps of post- and pre-monsoon periods. The spatial thematic maps of electrical conductivity (EC), sodium absorption ratio (SAR), residual sodium carbonate (RSC) and sodium percentage (Na%) were developed using a geographic information system (GIS) and compared with the respective United States Department of Agriculture (USDA) standards. The pertinent maps of irrigation water quality parameters based on FAO-29 guidelines were prepared, rasterized and overlaid using a GIS to develop IWQI maps for the basin. The IWQI maps indicated that 75% of the basin area possesses highly suitable irrigation water post-monsoon, with medium suitability (90.7% of the basin) predominating during pre-monsoon. Copyright © 2015 John Wiley & Sons, Ltd. RESUME Les variations spatiales et temporelles de la qualite des eaux souterraines du bassin de la riviere Araniar (Inde du Sud) ont ete etudiees afin de determiner l'aptitude a l'irrigation de la nappe a travers l'indice de qualite de l'eau d'irrigation (IWQI). Les cartes thematiques en periodes de pre et post-mousson de la conductivite electrique (CE), du ratio d'absorption de sodium (SAR), du carbonate de sodium residuel (RSC) et du taux de sodium (Na%) ont ete etablies en utilisant un SIG, et comparees aux normes de l'USDA. Les cartes de parametres de qualite de l'eau d'irrigation basees sur la directive FAO-29 ont ete preparees, pixellisees et superposees en utilisant SIG pour determiner l'indice de qualite de l'eau d'irrigation (IWQI). Les cartes IWQI ont indique que 75% de la superficie du bassin possede une eau d'irrigation tres appropriee en post-mousson et une aptitude moyenne (90.7% du bassin) predomine pendant la pre-mousson.

Energetic, Hydraulic and Economic Efficiency of Axial Flow and Centrifugal Pumps for Surface Water Irrigation in Bangladesh

Abstract: With conventional centrifugal (CEN) pumps, less than 50% of southern Bangladesh's farmers invest in irrigation, partly due to high diesel energy costs. New policies are prioritizing sustainable crop intensification in Bangladesh's delta. This objective is unlikely to be achieved without fundamental changes in the energetics and economics of irrigation. Where surface water is available, axial flow pumps (AFPs) may comprise part of the solution to this problem. Comparing the hydraulic, energetic and economic performance of prototype AFPs and CEN pumps, the latter produced less yet consistent rates of discharge than AFPs at all heads. AFP discharge was conversely larger than CEN pumps, but inversely related to increasing head. Discharge per unit of fuel was highest for AFPs (+51 and +21% at 1- and 2-m lifts), but declined with rising head until convergence with CEN pumps at 2.8 m. High AFP discharge reduced irrigation time requirements. On average, AFPs can save between US$70 and 38 ha–1 season–1 for boro rice at 1- and 3-m heads, respectively, and between US$15 and 8, and 26 and 14 ha–1 season–1 for wheat and maize. Fuel efficiency reductions above 2.8 m highlight the importance of improved prototyping and technology targeting to ensure AFP deployment in environments where the greatest efficiency gains are achievable. Copyright © 2015 John Wiley & Sons, Ltd.

Performance Assessment for Irrigation Water Management: Case Study of the Great Chao Phraya Irrigation Scheme

Abstract: The objective of this study is to assess the performance of irrigation water management of the Great Chao Phraya Irrigation Scheme consisting of 25 operation and maintenance irrigation projects (OMPs) in the Chao Phraya River Basin, central Thailand. Benchmarking is used to evaluate irrigation performance amongst the schemes. The eight performance indicators are crop yield ratio, output per unit area, operation and maintenance (O&M) cost, total financial viability, efficiency of infrastructure, sufficiency of irrigation staff, irrigation ratio and cropped area ratio. The results provide a feasible mechanism for performance improvement in the irrigation and drainage sector, but need strong support from key stakeholders. Though there are some uncertainties concerning the quality of secondary data, experience and insight gained from this study could provide valuable information for other schemes and will be a good starting point for benchmarking the performance of irrigation in Thailand. Copyright © 2015 John Wiley & Sons, Ltd.

Estimating Drainage Periods for Agricultural Fields from Measured Data: Data‐Mining Methodology and a Case Study (La JailliÈRe, France)

Abstract: The identification of intensive drainage periods is important for determining mitigation strategies for protecting water against pollution with plant protection products (PPPs). Most attempts to estimate the start, duration and the end of a drainage period are based either on mechanistic modelling approaches or on empirical knowledge about tile drainage. Mechanistic modelling requires many parameters, while the empirical approach does not allow for making the simulations and predictions needed for proposing reliable mitigation measures. In order to complement these two approaches, we have used a data-mining approach on data from 25 (1987–2011) agricultural seasons (campaigns) from the experimental station La Jailliere, France. The models for estimating the start and the end of the intensive drainage period for a particular campaign have the form of decision trees and tell us which factors influence these dates the most. The start of a drainage period depends mostly on the cumulative drainage and the cumulative rainfall since the beginning of the campaign and the average air temperature of the last 7 days. For estimating the end of a drainage period, the most important variables are the cumulative rainfall of the last 7 days and the average air temperature of the following 7 days. Copyright © 2015 John Wiley & Sons, Ltd.

Farmers’ Experience, Concerns and Perspectives in Using Reclaimed Water for Irrigation in a Semi‐Arid Region of Crete, Greece

Abstract: Public acceptance is recognized as an important ingredient for success in any recycling project. In case of reuse of treated wastewater for crop irrigation, farmers are the key stakeholders, being in a position to accept or reject reclaimed water. During this study, a survey was conducted to determine the perceptions and experience of farmers in a semi-arid region of Crete, Greece, where a wastewater reuse scheme has already been in operation for about a decade in irrigating olive orchards. Results show that a high proportion (77.4%) of the respondents view the reclaimed water positively for olive tree irrigation. On the other hand, a very low proportion was found for all the other irrigation options, with 7.9% for vegetables, 9.1% for vines and 25.8% for ornamental plants. Irrigation with reclaimed water had a positive impact on olive trees and soil according to about 56 and 40% of respondents respectively. Approximately 46% of farmers expressed willingness to pay for reclaimed water, while 94% of respondents suggested a price of up to €0.15 m−3. A clear correlation was found between levels of trust in the local authority responsible for the scheme and the farmers’ attitude towards reclaimed water. Copyright © 2015 John Wiley & Sons, Ltd. Resume Un des elements importants pour la reussite de tout projet de reutilisation est l'approbation du public. En ce qui concerne la reutilisation des eaux usees traitees pour l'irrigation de cultures, les agriculteurs sont des acteurs essentiels, car etant en mesure d'accepter ou de refuser l'utilisation des eaux recyclees. Tout au long de cette etude, une enquete a ete menee afin de determiner quelles etaient les opinions et l'experience des agriculteurs dans une region semi-aride de Crete, en Grece. Dans cette region, un systeme de recuperation des eaux usees fonctionne deja depuis environ une dizaine d'annees et est utilise pour l'irrigation des oliveraies. Les resultats montrent qu'un grand pourcentage des personnes interrogees (77.4%) approuve la reutilisation des eaux pour l'irrigation des oliviers. Toutes les autres options ont obtenu un faible pourcentage de reponses positives, comme 7.9% pour les legumes, 9.1% pour les vignes et 25.8% pour les plantes ornementales. L'irrigation avec des eaux recyclees a eu un impact positif aussi bien sur les oliviers que sur le sol, d'apres respectivement 56 et 40 % des personnes interrogees. Environ 46% des agriculteurs ont exprime leur consentement a payer des eaux recyclees tandis que 94% des personnes interrogees ont propose un prix allant jusqu'a €0.15 m−3. Il existe donc une correlation claire entre les niveaux de confiance en l'autorite locale responsable du projet et l'attitude des agriculteurs envers les eaux recyclees. Copyright © 2015 John Wiley & Sons, Ltd.

Water Distribution of Traditional Karez Irrigation Systems in Afghanistan

Abstract: Realizing the importance of Karez irrigation systems, field research was conducted in the district of Khwaja Omari of Ghazni (Afghanistan) to assess traditional water management practices in three selected Karez irrigation systems. In the Karez irrigation system, an informal water users’ association performs the function of water allocation, distribution, operation and maintenance of the physical infrastructure. Water is distributed on a rotational basis and each plot receives their due share of water once in the water distribution cycle that ranges from 6 to 12 days. The available flow discharges of three sampled Karez irrigation systems were measured that ranged from 6.30 to 9.28 l s−1 during the months of June to October and served cropped areas that varied from 12.53 to 24.15 ha. Conveyance losses measured in unlined irrigation canals varied from 21.9 to 32.7% km−1 with an overall average of 26.0% km−1. In general, crop water demands exceed available irrigation supplies particularly during the months of July and August. It may be concluded that water distribution is reasonable but can be improved further by considering the conveyance losses in these systems which will improve the overall productivity. Copyright © 2015 John Wiley & Sons, Ltd.

Simulating Groundwater Dynamics Using Feflow‐3D Groundwater Model Under Complex Irrigation and Drainage Network of Dryland Ecosystems of Central Asia

Abstract: Surface and groundwater resources are often conjunctively used to cope with water scarcity in irrigated agriculture. Farmers in the dryland ecosystems of central Asia also utilize shallow groundwater in addition to surface water withdrawn from rivers. This study modelled groundwater dynamics in an irrigation and drainage network in Khorezm region, Uzbekistan. The system, characterized by a vast, unlined channel network used to convey water mainly for flood irrigation and an open drainage system, is typical of Central Asian irrigated areas. Groundwater levels in the region are shallow—this contributes to crop water requirements but threatens crop production through secondary salinization. High losses during irrigation in fields and through the irrigation network are the main causes of these shallow groundwater levels. The main objective of this study was thus to simulate groundwater levels under improved irrigation efficiency scenarios. The FEFLOW-3D model, applied in a case study to the water users' association (WUA) of Shomakhulum in south-west Khorezm, was used to quantify the impact of improved irrigation efficiency scenarios on groundwater dynamics. The modelled scenarios were: current irrigation efficiency (S-A, our baseline), improved conveyance efficiency (S-B), increased field application efficiency (S-C), and improved conveyance and application efficiency (S-D). Recharge rates were separately determined for six hydrological response units (differing in groundwater level and soil type) and introduced into the FEFLOW-3D model. After successful model calibration (R2 = 0.94) and validation (R2 = 0.93), the simulations showed that improving irrigation efficiency under existing agro-hydroclimatic conditions would lower groundwater levels from the baseline scenario (S-A) in August (the peak irrigation period) on average by 12 cm in S-B, 38 cm in S-C and 44 cm in S-D. Any interventions which would improve irrigation efficiency will lower the groundwater levels and hence policy makers should consider them and formulate the policy accordingly. Copyright © 2015 John Wiley & Sons, Ltd.

Assessing the Design of A Model‐Based Irrigation Advisory Bulletin: The Importance of End‐User Participation

Abstract: Successful uptake of modern irrigation techniques and farmer decision support tools are necessary to promote the sustainable use of water resources. However, many of these tools fail to receive sufficient uptake from farmers to have a significant impact on water saving. End-user participation during tool development can increase the adoption rate as the tool becomes more usable. In the Segura River Basin of Spain, an irrigation advisory bulletin was designed to support farmers in their irrigation planning and scheduling. The bulletin was distributed to innovative farmers who are early adopters of modern irrigation technology. A formative evaluation procedure was applied to assess the acceptability of the bulletin against a number of non-adoption criteria, including irrelevance, inflexibility, inaccessibility, lack of confidence and institutional and political barriers. Feedback from the pre- and post-trial run surveys revealed that there were discrepancies between perceived and actual information needs by farmers, which include seasonal influences, water quality, salinity levels and crop life cycle. We demonstrate and argue the importance of assessing end-user needs again after the implementation of the decision support system in order to limit the risk of non-adoption. Copyright © 2014 John Wiley & Sons, Ltd.