Irrigation Water Distribution Research Articles

Crop Response to Combined Availability of Soil Water and Its Salinity Level: Theory, Experiments and Validation on Golf Courses

The phenomenological expression showing crop yield to be directly dependent on water deficiency, under saline conditions, has encouraged a continued focus on salinity as a viable approach to increase crop yields. This work reassesses crop response to availability of saline soil water ASW in two stages (A) Develop a simple approach suggesting that permanent wilting point (WP) increases under high saline soil water tension and relative yield of Lettuce (Lactuca sativa L., var longifolia Lam., cv. Nevada) and maize (Zea mays L., cv. Jubilee sweet) decrease. (B) Using a deterministic numerical soil water model to validate the theory on Bermuda grass of golf courses. The experimental plots were established in the North Negev, Israel (Sweet corn) and the Algarve, Portugal (Lettuce and Bermuda grass covering the golf courses). Sprinkler irrigation and line source techniques were used for water application, creating a saline gradient under a precise irrigation water distribution. Two salinity empirical models were tested (Mass and Hoffman MH and van Genuchten–Gupta vGG). Their empirical models were modified and instead of soil electrical conductivity of irrigation water (ECe) we used wilting point (WP) and RASW to follow the changes in relative yield. The validation was conducted with theoretical soil plant atmosphere water (SPAW) to predict the results on golf courses. It is concluded that an alternative S-shaped response model provides better fit to our experimental data sets. Modified MH model (Yr = Y/Ymax = a ∗ (ASW–threshold’s constant) revealed that a single dimensionless curve could be used to express yield—salinity interference when represented by varying ASW. The vGG model: vGG can represent salt tolerance of most crops, by using varying wilting point of average root zone salinity, at which the yield has declined by 50%. The abscissa of both models was based on WP rather than the standard soil electrical conductivity (ECw). The correlation between the experimental data and WP or relative available soil water (RASW) was acceptable and, therefore, their usefulness for prediction of relative yield is acceptable as well. The objectives of this study were: 1. To develop a simple model describing the effect of salinity through soil water availability on crop production; 2. To replace the standard varying soil electrical conductivity ECe used by MH and vGG models by two soil parameters (at wilting point- θwp and at field capacity θfc) in order to describe the relationship between them and relative yield. 3. Validate the new model with respect to independent salinity on Golf courses and a mathematical deterministic model.

Технико-экономическое обоснование стоимости транспортировки сточных вод для ирригационных целей в административном округе Кербела (Ирак)

Introduction. The study presents an assessment of the economic feasibility of different pipe materials used to transport treated wastewater. The choice was made between pipes made of ductile iron, glass-fiber reinforced polyester (GRP), concrete, and plastic. Hydraulic calculations of operation of an irrigation water supply and distribution system were made using WaterCAD V8i software. Two options of the system operation, that entail different flow rates and diameters, are considered: if the flow rate is equal to 1.16 m3/s and pipe diameters vary from 800 mm to 1,200 mm, and if the flow rate is equal to 4.63 m3/s, and pipe diameters vary from 1,600 to 2,000 mm. Materials and methods. The article analyzes the legal and regulatory documentation on design and construction, urban planning solutions for residential areas, architectural and structural solutions for apartment buildings, statistical and analytical reports on housing construction in Russia, presented on the Internet. Results. Irrigation water represents treated wastewater fed by the wastewater treatment facilities in the city of Karbala, Iraq. Two hydraulic models were designed with account for the above-mentioned costs. Head losses were estimated for each model with regard for all studied materials and pipe diameters using the WaterCAD V8i software and a mathematical model for the purpose of selecting the optimal pipe diameter. Conclusions. A mathematical model was developed to calculate the cost of transporting wastewater in pipes having different diameters and made of four different materials. The ratio of costs to the diameter of pipes, made of four different materials, was identified by developing an empirical equation. The co-authors used the Darcy – Weisbach technique and the Hazen – Williams method to calculate the operating costs with regard for variable diameters, flow rates for the two models, head losses due to friction, annual operation time, annual cost of electric energy, and the energy efficiency of the unit. Thus, a mathematical model was obtained, that can be applied to select the most optimal pipe diameter.

Linear Relationship of a Soil Total Water Potential Function and Relative Yield—A Technique to Control Salinity and Water Stress on Golf Courses and Other Irrigated Fields

A simple empirical approach is proposed for the determination of crop relative yield (%) through the soil total water potential (kPa). Recurring to decimal logarithms, from analytical exponential expressions, a linear simple relationship of soil total water potential Ψt (matric Ψm + potential Ψo) function and crop relative yield was studied and developed. The combination of the salinity model, the soil water retention model and the matric potential approach were used to reach this objective. The representation of turfgrass crop relative yield (%) versus a function of soil total water potential f(Ψt) values was shown through a log-normal graph (y = a + mx); the log scale axis “y” (ordinates) defines relative yield Yr, being two the origin ordinate “a” and “m” the slope; the normal decimal scale axis “x” (abscissa) is the function of soil total water potential f(Ψt). Hence, it is possible, using only two experimental points, to define a simple linear relation between a function of soil total water potential and crop relative yield, for a soil matric potential value lower than −20 kPa. This approach was first tested on golf courses (perennial turfgrass fields), but it was further decided to extend it to other annual crop fields, focused on the model generalization. The experimental plots were established, respectively, in Algarve, Alentejo and Oeiras (Portugal) and in the North Negev (Israel). Sprinkler and trickle irrigation systems, under randomized blocks and/or water and salt gradient techniques, were used for water application with a precise irrigation water and salt distribution. Results indicated that there is a high agreement between the experimental and the prediction values (R2 = 0.92). Moreover, the precision of this very simple and easy tool applied to turfgrass fields and other irrigated soils, including their crop yields, under several different sites and climatic conditions, can contribute to its generalization.

Assessment of the regional agricultural water-land Nexus in China: A green-blue water perspective

An appropriate agricultural water-land nexus can help to effectively take advantage of limited water and land resources, which is of great significance for guaranteeing food security. An R index was proposed to evaluate the regional agricultural water-land nexus from a green-blue water perspective in the current paper. The effects of irrigation on the agricultural water-land nexus were revealed for the first time based on this index in evaluations of all (Rt) and irrigated (Ri) arable land in the 31 provinces, autonomous regions and municipalities (PAMs) of China during 1999–2018. The national annual average values of Rt and Ri were 1.94 and 3.55 m3/m2, respectively; the former was steady during the observed period, while the latter showed a significant decreasing trend (P < 0.01) from 4.35 m3/m2 in 1999 to 2.66 m3/m2 in 2018. The values of both Rt and Ri values in South China were higher than those in North China. The maximum values of Rt and Ri appeared in Xizang (Rt = 99.15 m3/m2; Ri = 201.99 m3/m2), while the minimum values occurred in Ningxia (Rt = 0.30 m3/m2; Ri = 0.44 m3/m2). The Gini coefficient for Ri (Gi) in each year was higher than that for Rt (Gt), demonstrating that the agricultural water-land nexus in irrigated arable land was highly imbalanced during the last two decades. From the perspective of the equitable distribution of irrigation water, irrigation facilities should be developed in the Southeast and Southwest PAMs to improve the effective irrigation rate. In addition, the government should simultaneously implement water transfer plans to reduce the agricultural water pressure in the PAMs in the North China Plain and Northeast China.

Determinants of Onion Output Market Participation Level Among Smallholder Farming Households: The Case of Fentale District, Oromia Regional State, Ethiopia

This study focuses on analysing the factors affecting the decision and the level of onion output market participation among smallholder onion producers at Fentale district . Samples of 180 onion producer households were selected through multi-stage random sampling from three kebeles of Fentale district. The study employed both quantitative and qualitative methods of data collection. Quantitative data collected from sample households were analysed by descriptive and double hurdle model while qualitative analysed by narration. The result from the 1 st phase of the double hurdle, probit regression, revealed that sex of household head, onion farming experience, total farm holding, farm allocated for onion production, credit access, access to extension and market information were statistically significant and influence households onion market participation decision. The finding from the 2 nd phase of the hurdle model, truncated regression, show the age of household head, sex of household head, farm allocated to onion, irrigation access, number of oxen owned and distance to the nearest market were variables influencing smallholder onion market participation level and statistically significant. Finally it is recommended that the Government organizations and other responsible bodies should ensure the equal distribution of irrigation water for both upper and lower streams, strengthen inputs supply chains, and strengthen producers’ cooperation. Keywords: Double hurdle, Fentale, Market Participation , Onion, Smallholders DOI: 10.7176/JMCR/82-01 Publication date: September 30 th 2021

Development of application tools for determining cropping patterns based on water availability

Innovative irrigation is a vital factor in increasing water efficiency, gaining benefits, and reducing environmental burdens. Fulfilling irrigation water demand appropriately from time, space, quantity, and quality is the main factor in the irrigation water distribution pattern. A simple information system process, transparent and real-time reporting can reduce water sharing conflicts and improve irrigation operator performance. This research aims to determine the planting area refers to water availability through an automatic calculation application, where the water distribution is carried out based on the condition of the plant’s water demand at that time and several days after. The process of collecting the latest data by installing sensors or recording devices related to the analysis of water demand and availability parameters, such as climatological conditions, plants, and water in the rice fields and their sources, was needed as an input process the application. When the automation of operations operates, sensors on the rice fields plots send information directly to data companies that perform information analysis and send agronomic instructions to machines that regulate the release of the amount of water to the motion weir (smart agriculture management system). The way for determining the planting area and planting pattern calculated using the calculation application of the irrigation water demand, which developed with potential evapotranspiration values, reliable rain (R80), crop coefficient (Kc), and dependable discharge data (Q80) as the input data. This system’s output data consist of a table of irrigation water demand, a graph of the relationship between irrigation water demand and discharge availability for a year.

A Systematic Review of Ontology-Based River Streamflow and Flood Data Management Challenges

The management of the riverine water has always remained an open challenge. The variation of water flow creates hurdles to determine the exact time and the quantity of water flow caused by the spatio-temporal complex streamflow and flood risk reduction domain. From a management perspective, irregular flow patterns generate various challenges and the development of irrigation water distribution schemes without contextual knowledge integration adversely affect the relevant community. The river streamflow and flood mitigation domains are interdisciplinary that require coordination from the various stakeholders. Coordination limiting factors includes native data acquisition methodology of each stakeholder for their specific needs, the complexity of the domain involving a heterogeneous group of managers, spatio-temporal context, region-specific terminologies, data sharing, and reusability support. Earlier proposed research and developed ontologies by the esteemed researchers focused to address these challenges in a domain-specific context. In this research, we review the challenges of a large scale spatio-temporal system for streamflow of watersheds and flood disaster management based on the ontological semantic models. This research also examines the proposed ontological models for streamflow and/or flood domain, and how they address such challenges. Furthermore, a systematic review of the last two decades’ research articles is conducted and the findings are presented to assess the mappings of the challenges to proposed solutions through ontological modeling for streamflow and flood domain.

A framework to evaluate the factors influencing groundwater management in Water User Associations: The case study of Tafresh County (Iran)

In recent decades, due to the water shortage around the world and the importance of groundwater in agriculture, the role of Water User Associations (WUAs) – well-known farmer associations that manage collective irrigation in agricultural districts – in groundwater management has received much attention. To ensure sustainable groundwater management in these organizations, it is imperative to analyze the effects of the driving mechanisms, such as the “legal and institutional”, “socio-cultural”, “social capital”, “economic”, “infrastructure” and “farmers’ participation” factors, on the collective management of agricultural water. This study proposes a theoretical framework to analyze how and to what extent these factors influence agricultural water management in a case study of WUAs of Tafresh County (Iran), where irrigated agriculture strongly relies on groundwater. To validate this framework, questionnaires with 53 questions/indicators related to these factors have been supplied to 264 associated farmers and then statistically processed using Partial Least Squares – Structural Equation Modeling (PLS-SEM) methods. The measurement model has confirmed the validity of the questionnaire. The structural model has demonstrated that all the identified factors are significantly effective in driving the WUAs performance. This effectiveness was shown by the high indexes of reliability (over 0.821 against an acceptance limit of 0.7) and convergent validity (over 0.511 against a limit of 0.5). Socio-cultural and social capital factors had a higher impact (confirmed by path coefficients of about 0.80), while the economic factors played a lower effect on groundwater management (path coefficient of 0.534). Moreover, the Pearson matrix showed statistically significant (p < 0.01) and positive (R2 = from 0.238 to 0.804) correlations among all the evaluated factors. Based on this framework, some actions for improving the groundwater management at the collective level are suggested, such as: (i) the implementation of new water management technologies to increase the efficiency in extraction, distribution, and consumption of irrigation water; ii) strengthening the importance of social and cultural participation in the management of WUAs, in order to create formal and informal contexts for enhancing individual participation in the short and long-term; iii) designing appropriate financing factors and diversification of the sources of revenue to execute projects on shared water resources.

A simulation-based optimization model for watershed multi-scale irrigation water use with considering impacts of climate changes

It is attractive and advantageous to realize process-based optimization of irrigation water use on large scales. In this study, a simulation-based regional irrigation water optimization model (SRIOP) was developed for watershed-scale optimal spatial allocation based on dynamic responses of agro-hydrological process and its spatial differences. The SRIOP model tightly linked a field-scale agro-hydrological model (SWAP-EPIC) with an optimization algorithm (NSGA-II) in a regional multi-level optimization framework. It performed at three levels that sequentially dealt with optimal irrigation water allocation on field, irrigation district and irrigated watershed scales, with two objectives of maximizing yield/benefit and minimizing irrigation water. The model was tested with a case study in the major irrigation system (MIS) of middle reaches of the Heihe River basin, northwest China. The optimal spatial distribution of irrigation water showed a decreased variation coefficient (0.17) and increased irrigation benefit (9.8% higher) as compared with that of the present year, and better reflected the effects of multi-level collaboration and crop-soil field distribution. The impacts of climate condition changes on optimized results and resulting uncertainty were also quantified and evaluated through optimizations in different climate years. The case study indicated that the model is a computationally efficient and feasible approach for process-based optimization on large scales with considering impacts of climate condition changes.

Challenges of irrigation water distribution from the viewpoint of socio‐hydraulic relations*

AbstractEvaluation of the hydraulic performance of irrigation structures should be used in proper planning of water distribution and the removal of social tensions at water user level. There are several hydraulic indicators that could be interpreted based on social realities. In this study, besides determination of water distribution and conveyance indicators of the Behbahan irrigation scheme, social status was investigated in relation to them. Accordingly, adequacy, dependability and equity indicators in this scheme are poor. Meanwhile, 54% of water users are not satisfied with the performance of water delivery. Based on the questionnaires, training about water distribution is the main request by water users. In this research with a different view about the evaluation of irrigation schemes, existing problems were described from the social perspective. The adequacy indicator is in good condition upstream of the network, while in downstream it is about 40%. Although the knowledge and awareness of water users upstream and downstream are almost equal, only 50% of downstream water users have a relative desire to participate in water services (68% for upstream water users) and their satisfaction is within 20% (62% for upstream water users). Finally, evaluation of hydraulic indicators will be completed and will solve more problems, by considering the social roots of the results.

Non-structural modification of agricultural water distribution systems in large scale irrigation districts

The present study's primary objective is to investigate non-structural alternatives' effectiveness in providing a reliable agricultural water distribution in large scale irrigation districts. Accordingly, the following activities were conducted to accomplish the objective: i) developing an operation model of non-structural alternatives in MATLAB; ii) developing a simplified hydraulic flow simulation model in MATLAB, capable of being integrated the operation model. iii) operational performance appraisal of the developed model under the normal and water shortages scenarios, iv) spatial analysis of the obtained results with GIS to determine each alternatives' effectiveness. The developed model was tested on a real test case, extensive irrigation districts located in central Iran. Analysis of the obtained results reveals that employing the first to third non-structural alternative improved the mean value of the daily water distribution adequacy index by 6–8%, 10–11%, and 5–7% in the normal scenario, 4–5%, 8–7%, and 3–4% in the water scarcity scenario, compared to the water distribution process in the status quo. Besides, the alternatives lead to improving water distribution equity even under the water scarcity scenarios, where the equity improved by 10, 12, and 8% for the first through third alternatives compared to the status quo. Besides the technical assessment, a comprehensive evaluation concerning the non-structural alternatives' effectiveness was conducted, based on the environmental, agricultural, and social effects of these alternatives, to provide practical results. The latter assessment reveals that the second alternative's implementation is expected to lead to a remarkable 12% annual water extraction reduction from the aquifer, decommissioning about 1694 of the 14,440 authorized tube-wells within the district, and a 14.3% reduction in energy consumption. The results showed acceptable improvement in irrigation water distribution by employing non-structural alternatives under normal operating conditions and little improvement under water scarcity scenarios. It was shown that, given the limited infrastructure available in the irrigation districts in developing countries, improving operation management does not necessarily need massive investments in renovating and modernizing these districts.

Developing a smart operating system for fairly distribution of irrigation water, based on social, economic, and environmental considerations

The present study proposed a smart operating system consists of two primary components of i) unsupervised pattern recognition and ii) automated control system. The main goal is shifting the technical orientation of the single-objective automated operating system to a practical one included the sustainable development viewpoints, where the environmental, social, and economic considerations determine the priorities of surface water distribution within an irrigation district. A complementary component consists of the principal component analysis (PCA), and a crisp clustering method is developed to fulfill this objective. The proposed method was implemented in a real test case, Roodasht Irrigation District, in Iran. According to the PCA analysis, six features, encompassing socio-economic, environmental, and technical objectives, were selected as the clustering's dominant features. The district was regionalized to 6 regions based on the initial results of the clustering. The integration of a couple of the clusters occurred in the post-processing stage, and finally, the test case was grouped into 4 regions with different priorities for receiving the surface water. The priorities were served as penalty values orders in the objective function of the developed automated controller. A comparison of the developed smart system's obtained results by status quo reveals that moderately water distribution happened in normal and water shortage scenarios, where the Equity index obtained 8.5% and 11.5%, respectively. Also, reliable and adequate water delivered to regions belongs to the forth and first clusters, where 37% and 38% of the region supplied more than 80% of their demands under the two scenarios, respectively. It is worth noting that the mentioned achievement created in the forth and first clusters, with the minimum groundwater overexploitation, the maximum dependency of farmers on agricultural activities incomes, and the seasonal worker's highest rate of unemployment. The developed smart system is capable of implementing the practical action of fairly water distribution based on the sustainable development concept rather than the technical one. The proposed method is simply possible to change, add, or remove the features, based on different objectives or concerns in different study areas.

Reducing the conveyance losses in trapezoidal canals using compacted earth lining

Earth canals are subjected to seepage losses during the conveyance and distribution of irrigation water. With the current conditions of climate change and water scarcity, it is becoming crucial to conserve water. Canal lining is a common solution to minimize seepage losses. In this study SEEP/W model is used to investigate the effect of compacted earth lining characteristics on seepage from trapezoidal earth canals. The amount of reduction in seepage due to lining is quantified. Different scenarios for the hydraulic conductivity, thickness, and orientation (position) of compacted earth lining are evaluated. The results show that compacted earth lining is an efficient method to reduce conveyance losses. 99.8% of the water lost by seepage can be saved if highly compacted soil is used on the bed and sides. Partial lining can also be used, the most efficient orientation of lining depends on the canal’s width. Design charts and equations are suggested.

Agricultural crops programmed cultivation using intelligent system of irrigated agrocoenoses productivity analyzing

The article considers the possibilities of controlling the programmed cultivation of agricultural crops using an intelligent system for analyzing the productivity of irrigated agrocoenoses. The information support of the intelligent system is standard information about agrometeological conditions, technical parameters of irrigation systems and irrigation machines, as well as information about the amount of water resources allocated for irrigation. The obtained results provide a strict theoretical basis for solving the issues of irrigation water distribution and operational management of the irrigation regime, clarify and simplify the procedure for choosing the optimal variant of the irrigation system design solution, and make it possible to make reasonable decisions related to the rational use of water resources in existing systems.

Minimization of Operational and Seepage Losses in Agricultural Water Distribution Systems Using the Ant Colony Optimization

The present study’s main objective is to simultaneously minimize operational and seepage losses in agricultural water distribution systems, relying on the Ant Colony Optimization (ACO). For this purpose, the following arrangements were made: i) Hydraulic flow simulation of the distribution systems was conducted by developing an Integrator Delay (ID) model using MATLAB and appraisal performance of the water distribution system, ii) The seepage simulation alongside the system employing a calibrated and validated estimation equation, iii) developing the ACO model to minimize operational and seepage losses within the agricultural water distribution Systems. Two single-objective and one multi-objective functions were considered to minimize seepage loss, operational loss, and both loss components simultaneously. The Moghan irrigation water distribution system, Iran, was selected as the case study. Optimization results revealed that the first through third objective functions managed to reduce the total losses in the Moghan water distribution systems by, respectively, 0.39, 3.1, and 4% compared to the existing conditions. A comparison with the optimization results from LINGO, a nonlinear optimization model, was suggestive of the advantages of the ACO in terms of the optimal result and optimization time. The proposed method can be used as a practical measure to improve water productivity within the scale of agricultural water distribution systems by improving the manual operating system’s performance in the status quo.

Effects of coupling multiple factors on CaCO3 fouling in agricultural saline water distribution systems

Saline water is an alternative resource that could be used to meet agriculture irrigation demands. Fouling, particularly that caused by calcium carbonate (CaCO3), often occurs in saline irrigation water distribution systems, and severely restricts the utilization of saline irrigation water. So far, water acidification is the common practice for avoiding CaCO3 fouling. However, this approach is often ineffective and regularly contributes to environmental pollution. This study investigated an effective practice to overcome CaCO3 fouling issues by regulating shear stress, temperature and ions in saline irrigation water irrigation systems. The effects of different near-wall shear stress at 0.05, 0.20, 0.40 and 0.60 Pa, coupling with temperature of 10, 20 30 and 40 ºC and cations Mg2+ and Fe3+ were analyzed. Results demonstrated that the CaCO3 fouling rate was linearly increased at initial shear stress, while decreased at higher shear stress, and the highest fouling rate was observed at 0.40 Pa, ranging between 21.4%−80.3%. The coupling of temperature and cations with shear stress significantly (p < 0.05) affected the fouling growth rate at each shear stress. The differences in fouling rate (fitting curves slopes k > 1) among different shear stress get larger with increasing temperature, while they decreased and increased with the addition of Mg2+ and Fe3+, respectively, when compared with pure solution of CaCO3. Refinement analysis showed the largest unit-cell volume and lattice parameter of calcite at shear stress of 0.40 Pa, resulting in a significant effect on distribution of fouling particle sizes and morphologies. Moreover, some anti-fouling measures were further proposed based on the formation behavior of CaCO3 fouling. These findings might provide a new perspective to control CaCO3 with potential implications for sustainable saline water management for irrigation.

СОВРЕМЕННЫЕ МЕТОДЫ УПРАВЛЕНИЯ ПОЛИВАМИ НА ОРОСИТЕЛЬНЫХ СИСТЕМАХ ЮГА РОССИИ

The article deals with the issues of operational diagnostics of reclamation systems, which allow timely prevention of negative phenomena on the system and planning measures to improve its functioning and protect the environment. Operational management of irrigation is carried out in the process of implementing the operational modes of irrigation of agricultural crops in order to consistently ensure optimal soil moisture to obtain maximum yield by optimizing the timing and rates of irrigation based on current and forecast weather, agrotechnical, organizational and economic factors. The operational management of irrigation is most effective if it is based on the use of technical means for the rapid collection and processing of the necessary information in the presence of an appropriate technological service. Systematic (daily) accounting of weather and organizational and economic factors makes it possible to predict soil moisture reserves for the next 5-10 days and adjust the timing and rates of irrigation, taking into account the state of soil moisture in each field. The controlled subsystem is designed to supply and drain water, as well as regulate the reclamation regimes of agricultural lands. The control subsystem provides operational management of water flows in the reclamation system, reclamation regimes of agricultural lands, technical condition of the reclamation system. It makes decisions and transmits control signals or commands to the controlled subsystem, and also receives incoming information about the state of the control object. The general tasks of the indicated operation services are the issues of rational distribution of irrigation water among the relevant parts of the system and water user farms, including irrigation fields; organization of commercial and operational accounting of irrigation water with the mandatory determination of the amount of waste and collector-drainage water; control over the use of irrigation water and the ameliorative state of lands and the natural environment; carrying out maintenance and repair work; implementation of measures to improve systems and increase their technical level; implementation of operational diagnostics on systems and farms.

Challenges and Opportunities Towards Small-scale Irrigation Based Onion Production: The Case of Fentale District, Oromiya Regional State, Ethiopia

Onion is one of the important vegetable crops grown by farmers mostly for market purpose. This study focus on explore the challenges and opportunities of small-scale irrigation onion production at fentale district. Samples of 180 onion producer smallholder households were selected through multi-stage random sampling from the three kebeles of Fentale district. Sources of data were both the primary and secondary sources. The primary quantitative data were collected through Interview schedule while the qualitative were collected by FGD and KIIs methods. The data analysis methods also encompassed both quantitative and qualitative. Descriptive statistics (percentage) were employed to analysis quantitative data while qualitative data were analysed by narrations and interpreting the meaning of words. The result of the descriptive statistic reveals that the high cost of inputs, fluctuation in irrigation access, disease and pest, the input supply shortage, high labour cost, flood problem and informal sources of seed were the challenges of onion production at the study area. Besides the high income gained from onion, access to irrigation, good weather condition and the high yield of onion from a small plot were the major opportunities to produce onion at the area. Finally, the researcher recommended that the Government organizations and other responsible bodies should ensure the equal distribution of irrigation water for both upper and lower streams, and strengthen inputs supply chains.

Simulation and evaluation of agricultural water distribution and delivery systems with a Hybrid Bayesian network model

Regular appraisal performance of the irrigation water distribution systems from the adequacy, equity, and sustainable operation perspectives are essential due to the significant water losses that has been led by the improper adjustments of the hydraulic structures. Appropriate operational strategies could be adapted when the irrigation district authorities have a pragmatic approach to assess the hydraulic behavior of the system. This study develops an intelligent model for i) hydraulic simulation and ii) operational performance evaluation of the agricultural water distribution systems by employing a Hybrid Bayesian Networks (HBNs). The developed model was tested on a real test case located in Iran and under the different operational scenarios. In this regard, firstly, a hydrodynamic model of the test case was developed, calibrated, and validated to simulate the hydraulic condition of the irrigation canal based on a wide range of the canal inflow variations, called operational scenarios. Then, performance assessment was conducted for the scenarios based on adequacy, equity, and efficiency of water distribution perspectives. The results were employed for the training of the HBNs model. The HBNs model configuration was selected based on the irrigation district manages expectations, where the performance indicators of "adequacy," "efficiency" and "equity" of water delivery, needs to be calculated for the canal inflow variations in different operational scenarios. Validation of the developed HBNs model reveals that Mean Absolute Percentage Error (MAPE) and Coefficient of Determination (R2) of the superior model within the entire output nodes are 17.31% and 0.96, respectively. The results indicated the ability of the HBNs Model for the "Simulation/Performance Appraisal" of any operating systems in the irrigation districts. The developed model is a useful tool for i) periodic appraisal performance of the distribution system, ii) operational personals and ditch-riders, and iii) regionalization of the district to facilitate the recurrent inspections and field visiting.

Evaluating irrigation scheduling and application efficiency: baseline to revitalize Meki-Ziway irrigation scheme, Ethiopia

Irrigation scheduling and application efficiency were evaluated for Meki-Ziway irrigation scheme in an overall effort to revitalize the scheme. The evaluation was done on three furrows in each of the four farm plots. Field capacity, permanent wilting point and bulk density of the four plots were determined in the laboratory. We monitored furrow inflow rate, cutoff time and soil moisture content in the plots over a period of about 4 weeks. This monitoring was done during both periods of water availability and water scarcity. Our results show that on average 58% (range 42–77%) of the applied irrigation water in this scheme can be considered beneficial for crop growth. The results also show that soil moisture content at farm plots at the canal head sections was always between soil saturation level and permanent wilting point. For farm plots along the middle and tail sections of the main canal, soil water content would even fall below the permanent wilting point. This was caused by the absence of a water allocation system to ensure equity, and by large, channel seepage losses along the unlined main canal. To improve irrigation efficiency therefore, rehabilitation of the physical infrastructure of the scheme, more equitable irrigation water distribution in the scheme and improvement in on-farm irrigation water management are needed.