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Land consolidation projects (LCP) has been applied in various countries to decrease land fragmentation, to give field road and to create more appropriate regular parcel shapes besides many benefits to farmers. Moreover, LCP help to decrease the cost of irrigation system establishment. Türkiye aims to modernize open irrigation systems into pressurized systems with LCPs to save water due to climate change and global warming. However, previously published studies on the effect of LCP on designing pressurized irrigation network are not adequate. In this study, Eymir Village LCP in Türkiye was chosen as the material to investigate how can LCP affect the cost of the establishment of a pressurized irrigation system. In this context, two similation of irrigation systems are designed with help of geographic information systems (GIS) and are analyzed by COPAM (Combined Optimization and Performance Analysis Model) to optimize the hydraulic performance. Results show that land consolidation proved to be an effective tool to solve spatial problems related to improving the irrigation systems, technical problems related to the performance of the networks, and the equity of services (guaranteeing 98% satisfaction of users). And, it has the most important effect on the economic feasibility of pressurized irrigation network establishment whose cost can be decreased by 13.6% by LCP. [ABSTRACT FROM AUTHOR]

The main purpose of this paper was to study the effect of spatial variability of soil hydraulic properties (HP) and vegetation parameters (VP) (e.g., leaf-area index, LAI, and crop coefficient, Kc) on modelling agro-hydrological processes and optimising irrigation volumes at large scale. Based on this analysis, the effect of partly overlooking the spatial variability of soil HP and/or VP inputs was verified on a 140 ha irrigation sector in "Sinistra Ofanto" irrigation system in Apulia Region, Southern Italy. Five soil profiles were excavated and the HP were measured in all the soil horizons. Additionally, measurements of soil HP were taken in the surface soil layer in ninety sites distributed over the whole irrigation sector. All the HP measurements were carried out using tension infiltrometer. Remote sensing applications were used to obtain LAI and Kc using European Space Agency's (ESA) Sentinel-2 images with 10 m resolutions. First, distributed (on ninety polygons with an average area of about 1.5 ha) optimal irrigation volumes and related deep percolation volumes at a depth of 80 cm, were computed using an agro-hydrological model and accounting for the actual observed variability of soil HP and VP inputs. The sector scale irrigation and deep percolation volumes were obtained by aggregating the distributed irrigation volumes. This was considered as the reference scenario (hereafter DVS—Detailed Variability Scenario). Then, reduced variability scenarios (hereafter RVS—Reduced Variability Scenario) were considered, where the information on the actual spatial variability of the soil HP and VP was gradually overlooked to find the minimum data set needed to still have sector scale irrigation volumes and related deep percolation volumes comparable to those obtained under the DVS. Results showed that overlooking VP (RVS-VP) variability did not significantly change the optimal irrigation volumes and the deep percolation fluxes. By contrast, neglecting the HP variability (RVS-HP) showed significant effects on both the irrigation and percolation volumes compared to the DVS. The main practical finding was that, at least for the area investigated in this study, hydraulic characterization of one soil profile in an area of approximately 30 ha provides sector scale irrigation volumes and percolation fluxes comparable to those obtained under the DVS, thus by accounting for all the observed local variability. [ABSTRACT FROM AUTHOR]

Solar photovoltaic (PV) irrigation is increasingly used in agriculture, driven by its low operation cost and virtually zero emissions, providing electricity access in rural areas. However, the high investment cost requires an optimal design. The objective of this work was to develop a user-friendly tool to optimally size a PV generator that satisfies crop irrigation needs under local constrictions. The ODSIS (Optimal Design of Solar Irrigation System) tool, was organized in three calculation modules, preceded by two complements, which determine the daily crop irrigation needs and power demand of the pumping system. Then, the first module sizes the PV plant, considering a multiplication factor, and provides the PV production potential throughout each day of the season. The second and third modules evaluate the total investment cost and equivalent greenhouse gas emissions avoided by comparison with traditional energy sources. This tool was applied to a case study in Senegal for which a multiplication factor of 1.4 was obtained for the optimal PV plant size. Between 22% to 64% of the investment cost corresponded to the PV pumping system, depending on the irrigation technique. The use of PV energy in the case study would represent an annual economic saving for the farmer after 5 to 8 years of payback period, avoiding the emission of between 29.8 and 37.9 tCO2eq/year for the case study area. [ABSTRACT FROM AUTHOR]

In recent decades, on-demand irrigation systems have been promoted to increase water use efficiency. This study focused on the assessment of two traditional rotational pressurized irrigation systems with a central pumping station in the Foggia Province (Italy). Irrigation system A has an area of 564 ha with 319 pipelines and 251 hydrants, and irrigation system B has an area of 445 ha with 280 pipelines and 214 hydrants. The nominal discharge of each hydrant is 10 l/s. In each of the two irrigation systems, 1000 different operation scenarios were investigated using the COPAM model. To evaluate the performance of the systems, the indices of Relative Pressure Deficit (RPD) and Reliability (RI) were used. Results showed that the systems are quite flexible and allow the required flow rate to be increased by 1.6 times the peak period flow rate, if necessary. With such increased discharges, it is impossible to guarantee the RPD ( R P D ≥ 0 ) and RI (RI = 1) indices in 47% of the hydrants in the irrigation system A and in 36.9% of the hydrants in the irrigation system B. An updated methodology for optimizing the pipe diameters starting from the current situation was also implemented. Around 23% of pipelines in each system were changed with such methodology. After the new optimization, the number of unsatisfied hydrants in both systems decreased by 94.1% (from 118 to 7 hydrants) and 82.3% (from 79 to 14 hydrants), respectively. Thus, with this methodology, the irrigation system performance can be improved. [ABSTRACT FROM AUTHOR]

Traditional static design approaches are often challenged by multifaceted uncertainties such as climate change, future demand, supply options, high-tech opportunities as well as budgetary constraints. However, robust approaches that incorporate the option of flexibility combined with optimization advances are likely to meet threshold performance criteria with the least amount of associated expenses. To this aim, several countries have started the process of modernizing their irrigation schemes, foreseeing their on-demand operation. The re-modernized schemes are facing the challenge of the inadequacy of the service reported by the users/ratepayers, whose livelihoods are threatened by it as they mainly rely on agricultural production, and the sustainability of the modernization process. This study develops an adaptive framework that applies a two-pronged approach: it incorporates, on the one hand, a qualitative analysis through a rapid appraisal procedure (RAP) that fills the big data-gap issue, and a top–down approach on the other hand, mainly based on an iterative process that assesses the correlation between the flexibility of the service provided under uncertainties, as well as the financial feasibility. The latter is associated with the sensitive parameters of Clément's first formula mainly used in the Mediterranean Region to design on-demand irrigation systems, and more specifically: the elasticity assigned at the feed hydrant of the distribution network, the coefficient of utilization of the network in the peak period, and the quality of the service. Applied to a Tunisian case study, the results clearly show that when adequately combining the flexibility levels of these parameters, an optimal quality service may be achieved with an average cost increment ranging between 13 and 16%, with a view of proactively increasing the resilience of the irrigators' community. [ABSTRACT FROM AUTHOR]

The use of treated wastewater (TWW) as an alternative resource to fresh water (FW) for irrigation purposes is becoming increasingly important, especially in semiarid and arid regions. However, achieving success in crop production largely depends on the adoption of appropriate on‐farm management strategies aimed at optimizing crop yields, maintaining soil productivity and safeguarding the environment. For this purpose, predictive models are of particular interest. A safe irrigation management (SIM) model developed and tested in this research was used to schedule irrigation under controlled management tailored to the use of 1) TWW and 2) FW and to reproduce farmers' strategies. These management strategies aim to improve actual irrigation practices, accounting for water quality, soil characteristics, and crop yield. The results of the application of SIM on a citrus farm in Souss‐Massa, Morocco, show that the management strategy adopted by farmers withdraws considerable amounts of water and results in substantial drainage volumes compared to those in the SIM strategy. In the specific case of TWW, the strategy simulated by the SIM model resulted in a decrease in yield of approximately 4%, compared to the 23% decrease derived from the farmers' traditional strategy. Moreover, SIM allowed for great savings in terms of fertilizing elements and for the reduction in the movement of water and salts beyond the root zone, usually considered the main source of groundwater contamination. These results confirm the appropriateness of using prediction models and the accuracy of the SIM model in adapting irrigation strategies to TWW, which will be an integral part of the strategies that encourage their use in irrigated agriculture. Integr Environ Assess Manag 2020;16:910–919. © 2020 SETAC KEY POINTS: A model is developed that incorporates subroutines for 1) irrigation scheduling with treated wastewater, accounting for water quality and soil properties and combining water and salt conservation equations, and 2) simulating bacterial movement and assessing the infection risk of exposed farmers.For the first time, accurate irrigation management scenarios are defined that are tailored specifically to the use of treated wastewater on citrus, a strategic crop for Souss‐Massa, Morocco, that is experiencing a growing deficit of water resources.The appropriateness of using accurate prediction models that enable the adaptation of irrigation strategies to treated wastewater (TWW) is confirmed, which paves the way for field research to further encourage TWW use in irrigated agriculture, especially on high‐water‐demanding crops in semiarid and arid areas.It is confirmed that the safe irrigation management (SIM) model is an effective and powerful tool that supports the development of irrigation strategies to limit soil salinization effects and recover soil quality under TWW. [ABSTRACT FROM AUTHOR]

This paper mainly aims to illustrate an irrigation management tool to simulate scheduling of district-level water needs over the course of an irrigation season. The tool is mostly based on a daily model for simulating flow of water (and solutes) in heterogeneous agri-environmental systems (called FLOWS-HAGES). The model produces information on the daily evolution of: soil water contents and pressure potentials in the soil profile; water uptake and actual evapotranspiration; stress periods for each crop; return fluxes to the groundwater and their quality in terms of solute concentrations (e.g., nitrates). FLOWS-HAGES provides a daily list of hydrants to be operated according to water or crop-based criteria. The daily optimal sequence of hydrant use may thus be established by passing the volumes to be delivered on to the model for simulating the hydraulics of the irrigation network, in order to ensure that the discharges flowing inside the network of distribution pipes are delivered under optimal pressure head distribution in the system. All the above evaluations can be carried out in a stochastic framework to account for soil heterogeneity and climate changes. To illustrate the potential of FLOWS-HAGES, a case study was considered for a selected sector of the Irrigation District 10 in the “Sinistra Ofanto” irrigation system (southern Italy, Apulia region). In a 139 ha area (Sector 6 of the Irrigation District), soil profiles were analyzed for characterization of hydraulic properties variability. Hydraulic properties were determined by a combination of field and laboratory measurements. Model simulations were validated by comparing soil water storage simulated and measured by a sensor based on electromagnetic induction technique. Irrigation water volumes and frequency calculated by the model were compared to the volumes actually supplied by the farmers. Compared to the farmers behavior, the model simulates more frequent irrigations with lower irrigation volumes. Finally, some indexes of irrigation performance were calculated for each farm under study. The resulting maps provide useful information on the spatial distribution of farmer behavior, indicating the abuse or underuse of water as well as the fraction of the water lost by drainage following the irrigation method applied. [ABSTRACT FROM AUTHOR]

Providing adequate pressure at the hydrant is an issue of great importance in the operation of pressurized irrigation distribution systems (PIDS). The hydraulic performance of these systems can be quantified by selected performance indicators to describe the performance of an irrigation system with regard to the objectives set for that system. Several indicators have been developed and used so far for the performance analysis of pressurized irrigation systems. However, none of them provides a comprehensive definition of the sensitivity of operating hydrants to the variation in the upstream discharge. The objective of this study is to develop an indicator that can quantify the sensitivity of a hydrant to the changes occurring upstream of an irrigation system. A new definition of the indicator is proposed, by considering the changes in the hydrant reliability to the changes in the upstream discharge. In other words, the sensitivity of a hydrant is simulated on the basis of the variation of its reliability to satisfy the required pressure for adequate on-farm service. This concept was applied to a case study in Italy and it showed the importance of the sensitivity indicator as defined herein in the decision-making process for proper operation of pressurized irrigation systems. [ABSTRACT FROM AUTHOR]

Pressurized irrigation systems operating on-demand offer large flexibility to farmers for managing their irrigation practices. Within these systems, the fast moving water and the sudden closing of hydrants generates unsteady flow and may create a significant pressure variation in the pipes causing noise, vibration and, sometimes, also pipes’ collapse. The present study describes a simulation tool that was developed for the analysis of unsteady flow effects. A large number of configurations of hydrants simultaneously open has been used to reflect farmers’ behaviour. A new indicator, called Relative Pressure Variation (RPV), was proposed to evaluate the pressure variation occurring into the system in respect to the steady-state pressure. This is very relevant and can be used to identify pipes with potential risk of failure. In addition, an analysis with different gate-valves’ closing time was carried out. It demonstrated that closing time shorter than Tc = 3 s may create dangerous pressures for the pipes. [ABSTRACT FROM AUTHOR]

This paper deals with the issue of monitoring the spatial distribution of bulk electrical conductivity, ơb, in the soil root zone by using electromagnetic induction (EMI) sensors under different water and salinity conditions. To deduce the actual distribution of depth-specific ơb from EMI apparent electrical conductivity (ECa) measurements, we inverted the data by using a regularized 1-D inversion procedure designed to manage nonlinear multiple EMI-depth responses. The inversion technique is based on the coupling of the damped Gauss-Newton method with truncated generalized singular value decomposition (TGSVD). The illposedness of the EMI data inversion is addressed by using a sharp stabilizer term in the objective function. This specific stabilizer promotes the reconstruction of blocky targets, thereby contributing to enhance the spatial resolution of the EMI results in the presence of sharp boundaries (otherwise smeared out after the application of more standard Occamlike regularization strategies searching for smooth solutions). Time-domain reflectometry (TDR) data are used as groundtruth data for calibration of the inversion results. An experimental field was divided into four transects 30m long and 2.8m wide, cultivated with green bean, and irrigated with water at two different salinity levels and using two different irrigation volumes. Clearly, this induces different salinity and water contents within the soil profiles. For each transect, 26 regularly spaced monitoring soundings (1m apart) were selected for the collection of (i) Geonics EM-38 and (ii) Tektronix reflectometer data. Despite the original discrepancies in the EMI and TDR data, we found a significant correlation of the means and standard deviations of the two data series; in particular, after a low-pass spatial filtering of the TDR data. Based on these findings, this paper introduces a novel methodology to calibrate EMI-based electrical conductivities via TDR direct measurements. This calibration strategy consists of a linear mapping of the original inversion results into a new conductivity spatial distribution with the coefficients of the transformation uniquely based on the statistics of the two original measurement datasets (EMI and TDR conductivities). [ABSTRACT FROM AUTHOR]

Nowadays, some of the existing irrigation distribution networks (IDNs) are facing hydraulic performance problems, due partly to the ageing of pipe networks, initial design flaws, improper management or/and the increase in water demand. Rehabilitation of these networks may become an inevitable need to provide the best services to farmers. To this end, a comprehensive computer model was developed to assist planners and decision makers in the determination of the most cost-effective strategy for the rehabilitation of irrigation networks. This model incorporates an innovative algorithm for the automatic search of the best looping positions in the network. Two multi-objective optimizations were applied for the rehabilitation of a real medium-size network operating on-demand and by gravity, one included the looping option while the other excluded this option. The two Pareto fronts, associated with each optimization, clearly indicated that it is imperative to consider the localized loops option during the rehabilitation process as it provided superior cost-effective solutions. The comparison between two selected cases from each front showed that even though the two solutions offered the same magnitude of improvement to the network, a cost saving of about 77% is obtained by choosing the case with the looping option. The model developed in the framework of this work represents a powerful optimization tool for cost-effective rehabilitation of irrigation networks. [ABSTRACT FROM AUTHOR]

One of the major shortcomings of the Participatory Irrigation Management/Irrigation Management Transfer (PIM/IMT) programs undertaken in many countries of the world, is the predominant absence of Monitoring & Evaluation (M&E) systems specifically addressed to accompany these processes, and become a major instrument to correct, improve and learn. To contribute to closing this gap, this paper presents the main features of 'MONEVA', an M&E system tailored to PIM/IMT programs, and adapted to different Mediterranean Countries. The system is based on the principles of the Logical Framework Analysis (LFA), which permitted the development of objectives, outcomes, outputs and appropriate indicators for the monitoring of results. MONEVA is integrated with seven menus and many submenus which detailed description is reported in the embedded User's Manual. Only selected options are presented in this paper. The important and innovative features of MONEVA are its capacity to adapt to every country by using only the indicators relevant to the country, and a simple and objective system of evaluation. The results of its application in the pilot countries Jordan and Tunisia, i) demonstrated its flexibility to adapt to local contexts and the easiness of its application which supported its adoption, and ii) validated its characteristics as a Decision Support System (DSS), having a great potential for improving the implementation of the PIM/IMT programs, through the identification of their criticalities and thus, facilitating the definition of corrective actions at government and agency levels, but particularly, at the Water Users' Association (WUA) level. [ABSTRACT FROM AUTHOR]

The present study provides an assessment of the climate variability at a subnational scale, focusing on the case of the Apulia region, in Southeastern Italy. The variables considered for the purpose of a trend analysis were the minimum, maximum, and mean temperatures, and reference evapotranspiration. These are very important in an urban-rural planning context. The study was based on 38 monitoring stations and consisted in the application of the nonparametric Mann-Kendall test and a progressive trend analysis, both used to detect the changes. The 1950-2003 period was investigated on seasonal and annual scales. The results generally showed a warming process and an acceleration of the atmospheric evaporative demand which took place especially since the mid-1970s. The latter had a significant positive trend, while the period before the break point of the 70s had a cooling effect. Finally, the warming effect was more pronounced for minimum temperatures. [ABSTRACT FROM AUTHOR]

A major shortcoming of Participatory Irrigation Management and Irrigation Management Transfer (PIM/IMT) is the absence of Monitoring & Evaluation (M&E) systems that accompany these processes and become a major instrument to correct, improve and learn. Although at the global level some countries have exerted efforts to implement M&E systems, these still present limitations, as the review of the international experiences shows. The Mediterranean situation is even more dramatic since only Tunisia implements an M&E system, whereas Egypt has shyly moved in this direction with a limited practical application. This state of affairs led the authors to develop a set of guiding principles to develop an M&E system to be applied in countries where PIM/IMT is adopted. This paper revises the main international efforts devoted to assess the performance of PIM/IMT and the state of the art of these processes in Southern and Eastern Mediterranean Countries. Moreover, it sets the framework and analyses the main sustaining factors for the development of a new M&E system for these countries. [ABSTRACT FROM AUTHOR]

This paper deals with the issue of monitoring the horizontal and vertical distribution of bulk electrical conductivity, σb, in the soil root zone by using Electromagnetic Induction (EMI) sensors under different water and salinity conditions. In order to deduce the actual distribution of depth-specific σb from EMI depth-weighted apparent electrical conductivity (ECa) measurements, we inverted the signal by using a regularized 1D inversion procedure designed to manage nonlinear multiple EMI-depth responses. The inversion technique is based on the coupling of the damped Gauss-Newton method with truncated generalized singular value decomposition (TGSVD). The ill-posedness of the EMI data inversion is addressed by using a sharp stabilizer term in the objective function. This specific stabilizer promotes the reconstruction of blocky targets, thereby contributing to enhance the spatial resolution of the EMI reconstruction. Time-Domain Reflectometry (TDR) data are used as ground-truth data for calibration of the inversion results. An experimental field was divided into four transects 30 m long and 2.8 m wide, cultivated with green bean and irrigated with water at two different salinity levels and using two different irrigation volumes, to induce different salinity and water contents within the soil profile. For each transect, 26 regularly spaced monitoring sites (1 m apart) were selected for soil measurements using a Geonics EM-38 and a Tektronix Reflectometer. Despite the original discrepancies in the EMI and TDR data, we found a significantly high correlation of the means and standard deviations of the two data series, especially after filtering the TDR data. Based on these findings, the paper introduces a novel methodology to calibrate EMI-based electrical conductivity via TDR direct measurements by simply using the statistics of the two data series. [ABSTRACT FROM AUTHOR]

Irrigation distribution systems are generally branched. They can be designed using optimization models that minimize the cost of the pipes under a number of constraints. Urban water distribution systems are generally designed as a series of interconnected closed loops which provide these systems with sufficient capability to overcome local physical failures . However, they enormously increase both the computational effort and the network cost. This research proposes an innovative approach where localized loops are used as a cost-effective solution to improve the performance of branched on-demand pressurized irrigation systems. The position of a localized loop is identified based on the overall performance improvement that can be achieved. This strategy, when necessary, also involves the increase in significantly smaller pipe diameters, where performance improvement cannot occur solely by introducing localized loops. The new approach was applied to an irrigation district in Southern Italy operating on demand. It demonstrated its effectiveness by improving the system's overall hydraulic performance, while achieving more than 80 % cost savings, as compared to the classical rehabilitation approach. A dedicated software package that may serve, with further improvements, as a DSS platform, was developed and used to perform an accurate hydraulic performance analysis of the irrigation system. [ABSTRACT FROM AUTHOR]

Reliable parameterizations of water uptake under osmotic stresses depend on the appropriate description of the interacting effects of root distribution and activity over the root zone. These effects should be evaluated under transient salinity conditions. To show that, a crop was irrigated with three salinity inputs using a randomized block design. Root-zone water storage and pressure heads measured at the bottom of the root zone allowed to calculate the evapotranspiration under the different salinity levels imposed. Root densities were measured by direct sampling twice during the growth season. Transpiration was distributed along the root zone according to a Feddes-type sink term and a reduction function accounting for osmotic stress. These data allowed evaluating the effects on the reduction function of (1) the actual salinity and root distributions under different osmotic stress and (2) discontinuous osmotic stress conditions occurring locally in the root zone because of salt leaching. When considering the space-time salinity distribution and the specific root distribution, a unique reduction curve was found, independently of the salinity level of the irrigation water. The effect of discontinuous stress was modelled by introducing (1) a hysteretic behaviour in the salinity reduction function, to be applied only to root compartments actually experiencing discontinuous stress and (2) a scaling factor acting on the whole root zone, based on the ratio of the actual (induced by salinity) to the potential root density. Results suggested that the reduction of transpiration under salinity may be partly caused by irreversible physiological adaption of the roots to saline stress and partly by reduced root density. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The paper assessed the sensitivity of an integrated hydro-economic model, to provide a quantitative range of uncertainty in the impacts of climate change on water balance components and water use in the agricultural sector of Apulia region located in a semi-arid Mediterranean climate area in southern Italy. Results show that the impacts of climate change are expressed in the future by an increase in the net irrigation requirements (NIRs) of all crops. Total cultivated land is reduced by 8.5 % in the future, and the percentage of irrigated land decreases from 31 to 22 % of total agricultural land. Reduction in the irrigated land, together with the variation in the cropping pattern and the adoption of the different irrigation techniques, led to a decrease in water demand for irrigation across the entire region. The sensitivity analysis shows that the groundwater recharge has the lowest correlation to climatic parameters. Results are addressed to the scientific community and decision makers to support the design of adequate adaptation policies for efficient water management under the severe drought conditions that are likely to occur in the region according to climate change projections. [ABSTRACT FROM AUTHOR]

A deterministic-stochastic combined model named HydroGEN was developed, as described in a companion paper (Part I: Model development), to enable the simulation of demanded daily volumes and hourly flow rates during peak periods in pressurized irrigation delivery networks. The model was applied to a pilot large-scale irrigation system located in southern Italy for calibration and for testing its reliability in analyzing the operation of large-scale pressurized delivery systems through the simulated flow configurations. Daily input data on rainfall, temperature, solar radiation, wind speed and relative humidity were gathered from a meteorological station located within the study area, whereas information on local irrigation management practices were collected through interviews with farmers and from extension specialists. The model was tested at different management levels, from district to sector and hydrants. The model testing was supported by the use of high-resolution remote-sensing imagery acquired on a single overpass date in 2006 and then classified and recoded following a ground-truthing campaign conducted during the same year. Simulations were performed to identify the 10-day peak-demand period and to generate the hydrographs of daily volumes and of hourly flow rates. Results from the different simulations were compared with historical datasets of irrigation volumes and discharges recorded during the 2008 and 2009 seasons at the upstream end of the irrigation network under study, at a sector level during the 2007 season and at selected delivery hydrants during the 2005 season. Some discrepancies between simulated and recorded data were noted that can be related to small errors in estimating crop and soil parameters, application efficiency at field level, as well as to large variability in irrigation management practices followed by local farmers. Overall, the results from testing showed that the model is capable of forecasting with good accuracy the timing of peak-demand periods, the irrigation volumes demanded during the season, as well as the hydrographs of daily volumes and hourly flow rates withdrawn by farmers during these peak-demand periods, especially when it is applied to large multi-cropped command areas. [ABSTRACT FROM AUTHOR]

The objective of this work was to identify a new efficiency-driven pumping station regulation aiming at maximum energy savings in on-demand irrigation systems. This objective can be achieved by matching the discharge and the pressure head required by the network (characteristic curve of the network) during an entire irrigation season by regulating the operation of the pumping station on the basis of operating the pumps at maximum efficiency. The characteristic curve of the network can be obtained by using an appropriate stochastic generation and hydraulic model. Additional performance analyses were also carried out using the AKLA model in order to better characterize the hydraulic behavior of the irrigation systems under study. The characteristic curves of the centrifugal pumps were adapted to the network curve by equipping the pumping station with variable-speed devices. Several types of regulation based on variable-speed techniques were identified and analyzed. The energy consumption for each regulation technique was quantified for two on-demand irrigation districts in Southern Italy, managed by the Water Users Organization 'Consortium of Capitanata'. It was demonstrated that, in comparison with the current pumping station regulation, maximum energy savings may be achieved when pump regulation is carried out with variable-speed devices to maintain the pumps at maximum efficiency. [ABSTRACT FROM AUTHOR]

This study describes a model named HydroGEN that was conceived for simulating hydrographs of daily volumes and hourly flow rates during peak-demand periods in pressurized irrigation delivery networks with on-demand operation. The model is based on a methodology consisting of deterministic and stochastic components and is composed of a set of input parameters to reproduce the crop irrigation management practices followed by farmers and of computational procedures enabling to simulate the soil water balance and the irrigation events for all cropped fields supplied by each delivery hydrant in a distribution network. The input data include values of weather, crop, and soil parameters, as well as information on irrigation practices followed by local farmers. The resulting model outputs are generated flow hydrographs during the peak-demand period, which allow the subsequent analysis of performance achievable under different delivery scenarios. The model can be applied either for system design or re-design, as well as for analysis of operation and evaluation of performance achievements of on-demand pressurized irrigation delivery networks. Results from application of HydroGEN to a real pressurized irrigation system at different scales are presented in a companion paper (Part II: model applications). [ABSTRACT FROM AUTHOR]

The present work analyzes energy saving in on-demand irrigation systems served by an upstream pumping station. The objective of this work is to identify the best pumping station operating mode to optimize energy consumption. This objective can be achieved by matching the discharge and the pressure head required by the network (characteristic curve of the network) during the whole irrigation season with the pumping station characteristic curves. The characteristic curve of the network can be obtained using an appropriate stochastic generation modeling, and COPAM software was used in the present work. The characteristic curves of the pumps can be adapted to the network characteristic curve by equipping the pumping station with variable speed devices. Several types of regulation based on variable speed techniques were identified and analyzed. The differences in energy consumption for each technique were quantified for two on-demand irrigation districts in Southern Italy and managed by the Water Users Organization 'Consortium of Capitanata' . It was demonstrated that in comparison with the current pumping station regulation, energy savings of about 27 and 35% may be achieved for the two districts. [ABSTRACT FROM AUTHOR]

The variability of flow regimes in on demand pressurized irrigation systems leads to uncertainty in head at the nodes affecting the system performance, and thus it should be considered when designing and/or rehabilitating water distribution systems. Based on these considerations a new approach for the optimization of on demand pressurized irrigation systems is presented combining the minimization of cost with the maximization of reliability taking into account the stochastic variability of the flows into each section of the network. The new model, Clément and the cumulated random generated discharges model (FAO model) were applied to three pressurized irrigation networks of different dimensions (large, medium and small) operating on demand in Southern Italy. The optimization algorithm used in all the cases is the Labye iterative discontinuous method, a formulation of the dynamic programming. The results of the different models were compared showing that the cost of the optimal network calculated using the new model was reduced by more than 20%, without any significant decrease of the system reliability or reduction of the network capacity. [ABSTRACT FROM AUTHOR]

The article presents a study on the impact of the climate and land use on the hydrological cycle and the water balance components in Apulia, Southern Italy. The distributed catchment scale model (DiCaSM) was used in the assessment of the Candelaro catchment. The study intends to determine a reliable hydrological model that is used in the estimation of the water balance. Moreover, the study will be able to test the reliability of the generalized likelihood uncertainty estimation (GLUE).

Different groups of hydrants or configurations operate simultaneously in on-demand pressurized irrigation systems, generating different flow regimes. The varieties of flow regimes cause a variability in hydrant pressure and consequently an adequate analysis of the hydraulic performance of the system is needed for better operation and adequate management. A reliable performance assessment needs a modern diagnostic analysis in space and time. To this aim, this research assessed the hydraulic performance of an irrigation district distribution network calculating two performance indicators at hydrant level: relative pressure deficit and reliability, and integrated the outputs in a geographic information system environment providing a framework for a decision support system (DSS). The user friendly interface provides detailed, attainable and interpretable information to address the present scenario as well as the future development of the system, and facilitates the cooperation among researchers, managers, and manufacturers to improve operation, maintenance, and management activities. [ABSTRACT FROM AUTHOR]

This study was conducted on an irrigated area of southern Italy to analyze the current operation of a large-scale irrigation delivery system and the effects of the operation procedures on crop irrigation management and aquifer salinity increase. The area is characterized by relatively high levels of groundwater salinity in the summer that are probably due to intensive groundwater pumping by farmers during periods of peak irrigation demand, with the resulting seawater intrusion. Two alternative delivery schedules, namely the rotation delivery schedule and the flexible delivery schedule, referred to as RDS and FDS, respectively, were simulated using a soil-water balance model under different combinations of crop, soil and climatic conditions. The first set of simulations concerned the farm irrigation management constrained by the rotational delivery used by the local water management organization. The second scenario simulated the farm irrigation schedule most commonly used by growers in the area for maximizing crop yields. Based on crop irrigation management under RDS and FDS, two alternative operational scenarios were also developed at the scheme level and then compared for evaluation. Winter and summer salinity maps of the aquifer were developed by interpolating salinity measurements of the groundwater samples collected during the 2006 irrigation season. From these maps, a close relationship can be inferred among delivery schedule, aquifer exploitation and salinity increase, which justifies the need for implementing FDS that might reduce the groundwater demand for irrigation. [ABSTRACT FROM AUTHOR]

Water scarcity is a mounting problem in arid and semi-arid regions such as the Mediterranean. Therefore, smarter and more effective water management is required, especially in irrigated agriculture. One of the most challenging uncertainties in the operation of on-demand collective Pressurized Irrigation Distribution Systems (PIDSs) is to know, a priori, the number and the position of hydrants in simultaneous operation. To this end, a model was developed to generate close to reality operating hydrants configurations, with 15, 30 or 60 min time steps, by estimating the irrigation scheduling for the entire irrigation season, using climatic, crop and soil data. The model is incorporated in an integrated DSS called Decision Support for Irrigation Distribution Systems (DESIDS) and links two of its modules, namely, the irrigation demand and scheduling module and the hydraulic analysis module. The latter is used to perform two types of analyses for the performance assessment and decision-making processes. The model was used in a real case study in Italy to generate hydrants' operation taking into consideration irrigation scheduling. The results show that during the peak period, hydrants simultaneity topped 62%. The latter created pressure deficit in some hydrants, thus reducing the volume of water supplied for irrigation by up to 87 m3 in a single hydrant during the peak demand day. The developed model proved to be an important tool for irrigation managers, as it provides vital information with great flexibility and the ability to assess and predict the operation of PIDSs at any period during the irrigation season. [ABSTRACT FROM AUTHOR]

We analysed the hydrological behaviour of a wadi basin in Egypt, whose channel was modified into levelled terraces for cultivation. A yearly data set was used, consisting of weather data, distributed water content measurements in the terraces of the wadi channel, and run‐off discharges at the wadi outlet. A modelling approach combining a run‐off model and an agro‐hydrological model was tested to simulate, respectively, the water stored in the wadi stream bed after a single rainfall event and the depletion of the stored water by evapotranspiration in the period between two subsequent rainfall events. Calibration and validation of the run‐off model were based on both basin outlet run‐off and distributed water storage measurements. High Nash–Sutcliffe efficiencies were obtained for both distributed channel water storage and outlet discharges, showing the importance of having available distributed storage measurements, besides basin outlet discharges, to obtain more robust model predictions. The soil–plant–atmosphere model was not calibrated as the parameters for the hydraulic properties, all coming from direct measurements, proved to describe effectively the distributed water storages measured in the terraces during the monitoring campaign. It was observed that the terraces (about 100,000 m3) may store up to 50,000 m3 of water. By considering that in the soil considered, the water content at the wilting point is about 5% and that in July, the soil profile is still able to retain about 40% of the initial volume, most of the water stored may be used by crops for the whole spring–summer period. [ABSTRACT FROM AUTHOR]

The perturbation in hydraulic networks for irrigation systems is often created when sudden changes in flow rates occur in the pipes. This is essentially due to the manipulation of hydrants and depends mainly on the gate closure time. Such a perturbation may lead to a significant pressure variation that may cause a pipe breakage. In a recent study, computer code simulating unsteady flow in pressurized irrigation systems—generated by the farmers' behavior—was developed and the obtained results led to the introduction of an indicator called the relative pressure variation (RPV) to evaluate the pressure variation occurring into the system, with respect to the steady-state pressure. In the present study, two indicators have been set up: The hydrant risk indicator (HRI), defined as the ratio between the participation of the hydrant in the riskiest configurations and its total number of participations; and the relative pressure exceedance (RPE), which provides the variation of the unsteady state pressure with respect to the nominal pressure. The two indicators could help managers better understand the network behavior with respect to the perturbation by defining the riskiest hydrants and the potentially affected pipes. The present study was applied to an on-demand pressurized irrigation system in Southern Italy. [ABSTRACT FROM AUTHOR]