Large-scale Irrigation Systems Research Articles

Performance evaluation of irrigation outlets with physical model study in Indus basin irrigation system of Pakistan.

The efficiency of water distribution at primary, secondary, and tertiary levels in the Indus Basin Irrigation System (IBIS) has historically suffered due to poor design, suboptimal operation, and water scarcity. To address these issues, the system has been designed with ungated irrigation outlets to ensure equitable water allocation at secondary and tertiary levels. This research evaluates the hydraulic performance of three irrigation outlets: adjustable proportional module (APM), adjustable orifice semi-module (AOSM), and open flume (OF) using a physical model study. A distributary channel model with these outlets was constructed at the Centre of Excellence in Water Resources Engineering, where discharge coefficients (Cd) were calibrated and measured under various hydraulic and geometric conditions, including free and submerged flow conditions, and with adjustments to flow depths and outlet settings. The results showed variability in Cd values under free flow and submerged flow conditions with APM and AOSM ranging from 6.07 to 8.20 and 0.56 to 0.74, respectively, and OF between 2.46 and 4.31. Additionally, the behavior of outlet tampering on Cd values was also assessed under three scenarios: tampering with the half wing wall (1st), tampering with the full wing wall (2nd), and lowering the bed level downstream of the outlet (3rd). The increase in Cd values for APM and AOSM was + 10.84% and + 14.49% under 1st scenario, + 17.12% and + 22.36% under 2nd scenario, and + 24.25% and + 26.30% under 3rd scenario, respectively. The results reveal that even minor tampering with outlet structures can lead to significant deviations in performance, highlighting the importance of maintaining stringent control over outlet configurations to ensure equitable and efficient water distribution. There is a critical need for rigorous, site-specific calibration of irrigation outlets to optimize their performance under local conditions and redesigning outlet structures to minimize the impacts of tampering, thereby enhancing the overall sustainability of water use in large-scale irrigation systems. The findings from this study provide essential insights for irrigation engineers and policymakers tasked with upgrading and maintaining irrigation infrastructure. By adopting a more customized approach to outlet design and management, it is possible to significantly improve water use efficiency and achieve more sustainable irrigation practices.

Multiscale spatial variability in land and water productivity across the Gezira irrigation scheme, Sudan

Agricultural performance assessment spans various spatial scales, from single plots to entire irrigation systems. A multi-scale analysis is thus crucial for informed decision-making. The Gezira irrigation sScheme in Sudan is a longstanding large-scale irrigation system experiencing severe water management challenges, manifested by low land productivity, water productivity, and irrigation efficiency. Recognizing the interdependence of decision-making, this research focuses on variations in water and land productivity at different spatial scales within the Gezira irrigation scheme. As one of the world’s largest gravity-irrigated systems, covering 2.1 million feddan (1 feddan = 0.42 ha ∼ 1 acre), the scheme serves as an interesting case to study head-tail performance variations across four spatial scales: tertiary, secondary, and major units, and the whole scheme. This study is centered on the winter season wheat cultivation 2022–2023, and employs the FAO’s Water Productivity Open Access Portal (WaPOR v2.1) datasets, with 100 m resolution, for computing land and water productivity. Ground-observed yield data from nine tertiary units (nimras) in the Wadelbur irrigation division were used to validate WaPOR. The results showed a systematic underestimation of WaPOR derived land productivity by about 40 % compared to the ground dataset. The head-tail analysis of land and water productivity reveal contrasting results at different scales. At tertiary and secondary scales, no correlation exists between distance from offtake and productivity. At the major unit (irrigation division), a moderate correlation is observed: 0.7 for land productivity, and 0.6 for water productivity. At the scheme scale, the correlation factors are somewhat lower for land productivity (0.4) and the same for water productivity (0.6). At the largest scale, the productivity appears to increase from head to tail divisions, suggesting potential overirrigation and waterlogging in the head parts leading to reduced productivity. Another possibility is the presence of better agricultural practices in the tail areas compared to the head.

DIGITALIZATION OF IRRIGATION SYSTEMS FROM WATER MANAGEMENT MAPS

With the increasing intensity of evapotranspiration caused by the changing climate, there is a growing need for water. This is especially true in locations where water-intensive vegetables are grown in intensive agriculture. Historically, irrigation systems were built in many intensive agriculture areas in Czechia, but they fell out of use, and evidence of their location was lost. However, Water Management Maps, which were only issued in paper form and have never been fully digitized, can provide evidence about the location of these large-scale irrigation systems. In this paper, we present a method for digitizing irrigation systems using the segmentation and classification of individual segments in the ArcGIS environment. The resulting raster is converted to polygons and is blended with the Land Parcel Identification System layer, resulting in a layer of irrigated land. Two statistical analyses were performed on this layer: statistics of the areas corresponding to the individual source watercourses, and statistics of the type of source.

TS fuzzy control of PV assisted single phase three phase induction motor drive for rural pumping applications

The motor drives for aqua farms and large-scale irrigation system needs a reliable electric drive, which requires the continuous power supply and efficient control. However, the rural single phase power supply is frequently interrupted. Renewable assistance would improve the availability of supply and heuristic control approach improves robustness in control. This paper presents a three phase induction motor drive fed from single phase electric grid with assistance from PV and battery energy storage. TS- fuzzy based direct torque control is employed for robust control during load changes, and the topology, component modelling, front-end converter control, PV interface DC–DC converter control, and inverter control are presented. MATLAB/Simulink is used to simulate the proposed drive system. The performance of the proposed system is validated using simulation data for both steady-state and transient states.

An empirical assessment of the institutional performance of community-based water management in a large-scale irrigation system in southern Mexico

Understanding irrigation performance by focusing on its institutional dimension can help improve water use and smallholder farmers' livelihoods. While many studies have evaluated the institutional performance of small-scale, farmer-managed irrigation systems, virtually no empirical studies have evaluated the performance of community-based water management institutions in large-scale irrigation systems with non-governmental bureaucratic administration. This study aims to fill this gap using a mixed-methods research design combining ethnographic work and a quantitative survey of 81 smallholder farmers' from four community institutions (ejidos) in an irrigation district in Chiapas, southern Mexico. While the management model implemented in the transfer of Mexican irrigation districts to users consisted of a bureaucratic administration entirely in the hands of contract agents, this study reveals the essential role of community institutions in local water management. However, although all four communities use water from the same irrigation district, the results revealed significant differences in the institutional performance of irrigation management. Using the Institutional Analysis and Development (IAD) framework developed by Elinor Ostrom, We showed that these differences could be explained by the biophysical attributes involved in irrigation (irrigation technique, access to groundwater resources, location of the water intake) and community characteristics (social capital and group size). The study recommends that water managers involve communities in the creation of farmers' associations, which could increase their social capital and thus the performance of local irrigation. Furthermore, the results suggest that farmers' views on the institutional performance of irrigation management should receive more attention in the large-scale irrigation system with bureaucratic administration. This knowledge can be particularly useful to improve the different levels of organization and thus water governance of irrigation districts in Mexico.

The Dominance-based Rough Set Approach for analysing patterns of flexibility allocation and design-cost criteria in large-scale irrigation systems

Water planners must provide end-users with reliable and high-quality access to fresh water while complying with financial, institutional, and water availability constraints. In the pursuit of these goals, an over-investment in design can result in stranded assets of significant value and often unwanted environmental implications. Under-investment can lead to supply restrictions affecting human health, the economy, and the environment. The present study uses the Dominance-based Rough Set Approach (DRSA) to develop a balancing strategy concerning complexities encountered in water resource planning for irrigation systems. The methodology relies on the Dominance-based Learning from Examples Module (DOMLEM) algorithm, which extracts minimal set of rules regarding relevant combinations between flexibility allocation and design-cost criteria. The algorithm delineates outcomes in the form of “if., then.” rules that translate decision possibilities facing water planners into: “if (the design is more flexible by this amount), then (we expect this range of cost increment”). Then, a confusion matrix is computed for each irrigation system in order to exclude the rules generating incorrect and ambiguous classification results. The outcome reveals that cost is more subject to elasticity at the hydrant (eh) increment than the network’s coefficient (r). Furthermore, the analysis reveals that the parameter P(q) has only a minor impact on the cost and, as a result, the final decision. Any elasticity (eh) less than 3 assigned to any given coefficient (r) becomes a low-cost increment. For any given value of (eh), the cost increases as the coefficient (r) decrease. Elasticity from 4 to 5 with a network's coefficient (r) equal to or greater than 18/24 becomes a medium-cost increment. Elasticity (eh) from 5 to 6 associated with an (r) equal or less than 16/24 becomes a very high-cost increment. Finally, rather than identifying one solution that seems better than others, this approach provides an interactive schematic that helps identify the appropriate range of flexibility justified by the expense criterion, which allows for debate and supports decision-making.

Elimination of Clogging of a Biogas Slurry Drip Irrigation System Using the Optimal Acid and Chlorine Addition Mode

As an emerging contaminant, the clogging substances of emitters in biogas slurry drip irrigation systems affect the efficient return and utilization of biogas slurry to the field to a great extent. This can be prevented using acid and chlorination as engineering measures. Through a hydraulic performance test and sampling detection and analysis, under the same acid addition conditions (pH = 5.5–6.0), three chlorine addition concentrations (0, 1–3, and 4–9 mg/L) and four chlorine addition cycles (6, 10, 14, and 20 days) were tested, aimed to clarify the influence of acid and chlorine addition parameters (chlorine adding cycle, chlorine adding concentration, etc.) on the anti-clogging performance of emitters in biogas slurry drip irrigation system. The results showed that compared with no acid and chlorination treatment (CK), only acid and a reasonable combination of acid and chlorination can significantly reduce the probability of serious and complete clogging of biogas slurry drip irrigation emitters, and they can stabilize the relative average flow of emitters by more than 75%. The measures of adding acid and chlorine change the distribution characteristics of clogging substances at the front and rear of the drip irrigation belt. Furthermore, they promote the migration of clogging substances to the rear of the drip irrigation belt, facilitating the clogging of emitters located thereat. The measures of acid addition and sequential addition of acid and chlorine significantly inhibit the growth of an extracellular polymer in the emitter, and the effect of inhibiting the increase in extracellular polymer concentrations is relatively poor when the acid addition period is excessively long or short. There exists a negative correlation between the extracellular polymer content in the emitter and the change in the emitter flow. Based on the obtained results, to ensure excellent anti-clogging performance of biogas slurry drip irrigation systems, for acid-only treatment measures, the acid dosing cycle is recommended to be 10 days. When acid and chlorination measures are implemented sequentially, the acid chlorination cycle is recommended to be 14 and 10 days when the chlorine concentration is 1–3 and 4–9 mg/L, respectively. This study has important scientific significance and practical value for the establishment of long-term operation management and protection technologies of large-scale biogas slurry drip irrigation systems.

Optical Sensor System for Early Warning of Inflow Organic Matter Breach in Large-Scale Irrigation Systems and Water Treatment Systems

A growing world population together with a decrease in water resources have resulted in a deficit in water sources for agriculture. Nations with limited water resources are already using recycled treated water as a vital water source for irrigation. In 2019, treated wastewater made up 45% of the overall agricultural water consumption in Israel. Since recycling systems work continuously and are directly connected to irrigation reservoirs, there is a constant risk of irrigation system malfunctions in the treatment process. In cases of fecal origin, this may result in pathogens entering the irrigation water, the soil, and eventually the food chain. Early warning systems for biological water contamination are important in large-scale processing, yet less studied. This work proposes such a system, with a functional prototype for irrigation-water monitoring by measuring fluorescence spectra in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300-520 \textit {nm}$ </tex-math></inline-formula> at excitation wavelengths of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$280 \textit {nm}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$340 \textit {nm}$ </tex-math></inline-formula> , to capture both tryptophan-like fluorescence and humic-like fluorescence. The prototype was successfully tested under simulated field conditions with treated irrigation water as the base substance, and milk injections to simulate dissolved organic matter breaches. Near real-time operation enabled recording biological and chemical dynamics within the substance for the sake of monitoring drift in process control.

Reign of Utpala Dyansty with Special Reference to Avantiverman (855-883 A.D): His Irrigation Works and Agricultural Development-A Historical Study

In Rajatarangni, dynasties in ancient Kashmir that dated from the time of the Mahabartha epic to the reign of Sangrama Deva are vividly portrayed. Of all the kings of ancient Kashmir, Avantivarman, who established the Utpalas dynasty in 1855 A.D., was the most magnificent. In terms of prosperity, he ruled during the rippling times of peace and plenty, which coincided with Kashmir reaching its pinnacle around a quarter of a century into his rule. The people had never been happier than they were in his day, nor had they been for generations. Therefore, Avantivarman rule represents a very wonderful era in Kashmir's history. A new period in that nation's history began with Avantivarman taking control of events in the valley. His rule not only provided respite to Kashmir's suffering people, but it also significantly restored the Karkota's former luster, as will be seen. Avantivarman, a descendant of the Kalyapala family and the grandson of Utpalas, who had played a crucial role in the final years of the Karkota monarchy, was previously mentioned. Avantivarman has the traits of intellect and heart that allow him to be recognised as one of the valley's most capable kings, while not being by any means a member of some aristocratic and distinguished family. The study's goal is to explain and analyze Avantivarman legacy and reign during the Utpalas Dynasty in Jammu and Kashmir. It also highlights his contributions during his time in power there. Fertile soil and abundant water availability in Kashmir have made agriculture the primary food and economic source for the region from ancient times. During Avantivarman's rule, both the people and the state's economic prosperity improved significantly due to political stability and beneficial peace conditions. Large-scale drainage and irrigation systems played an important role in this. All of these tasks were made easier by the irrigation minister (Suyya).

Reign of Utpala Dyansty with Special Reference to Avantiverman (855-883 A.D): His Irrigation Works and Agricultural Development-A Historical Study

In Rajatarangni, dynasties in ancient Kashmir that dated from the time of the Mahabartha epic to the reign of Sangrama Deva are vividly portrayed. Of all the kings of ancient Kashmir, Avantivarman, who established the Utpalas dynasty in 1855 A.D., was the most magnificent. In terms of prosperity, he ruled during the rippling times of peace and plenty, which coincided with Kashmir reaching its pinnacle around a quarter of a century into his rule. The people had never been happier than they were in his day, nor had they been for generations. Therefore, Avantivarman rule represents a very wonderful era in Kashmir's history. A new period in that nation's history began with Avantivarman taking control of events in the valley. His rule not only provided respite to Kashmir's suffering people, but it also significantly restored the Karkota's former luster, as will be seen. Avantivarman, a descendant of the Kalyapala family and the grandson of Utpalas, who had played a crucial role in the final years of the Karkota monarchy, was previously mentioned. Avantivarman has the traits of intellect and heart that allow him to be recognised as one of the valley's most capable kings, while not being by any means a member of some aristocratic and distinguished family. The study's goal is to explain and analyze Avantivarman legacy and reign during the Utpalas Dynasty in Jammu and Kashmir. It also highlights his contributions during his time in power there. Fertile soil and abundant water availability in Kashmir have made agriculture the primary food and economic source for the region from ancient times. During Avantivarman's rule, both the people and the state's economic prosperity improved significantly due to political stability and beneficial peace conditions. Large-scale drainage and irrigation systems played an important role in this. All of these tasks were made easier by the irrigation minister (Suyya).

Water Scarcity, Mountain Deforestation and the Economic Value of Water in a Small-Scale Irrigation System: A Case Study in East Java, Indonesia

Abstract The purpose of this study was to identify the willingness of farmers to pay for small-scale irrigation (SSI) and its determinants. Additionally, this study analysed the physical water availability in the study area using 16 years’ (2004–2019) historical data of streamflow, rainfall and forest cover change. A structured questionnaire was used to collect the data from 100 farmers. A contingent valuation method was employed to elicit farmers’ willingness to pay (WTP) for irrigation water. The results show that the average WTP of farmers is US$ 215.84/ha/year. It accounts for 20% of farm revenue and is almost 20 times the water fee in large-scale irrigation systems. The study area experienced significant deforestation in the last two decades suffering a decrease of 11.72% of forest cover. It decreases the amount of stored rainwater and decreases the streamflow causing water scarcity during the dry season. Farm size, farmer income, distance to a small dam and usage of water-pump are the significant determinants. The results indicate that water scarcity caused by poor infrastructure increases the economic value of water in a SSI system.

Performance enhancement of solar photovoltaic system for roof top garden.

The photovoltaic (PV) for irrigation system is an emerging technology to harness the solar energy. The performance of the PV modules depends on the incident solar radiation, geographical location, and the surface temperature of the modules. The performance of the PV system needs to be monitored by manually or embedded controllers. The commercially available technologies for monitoring the system are costlier and need to be optimized. The Arduino controller is used to monitor the performance of the photovoltaic (PV) system in Coimbatore (11.016° N, 76.9558° E), Tamilnadu, India. The PV surface temperature is monitored and controlled by flowing the water above the module by setting the mean ambient temperature as a reference temperature 34 °C when the system exceeds the reference temperature. PV surface temperature is reduced up to 16°C thus improved the electrical efficiency by 17% compare to the reference module. The Arduino controller control the relay to switch on the motor to control the mass flow rate of the water at 0.0028kg/s. The various parameters are measured such as voltage, current, and solar radiation of the location and analyzed. The estimated cost of monitoring system and various sensor is 10$ which cost comparatively 50% lower than the other PV monitoring controllers. This method can be employed in the medium and large-scale irrigation system.

Assessing the correlation between service flexibility and the cost of modernized large-scale pressurized irrigation systems: a perspective of resilience

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 Clement’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.

Strategic asset management approach for planning investment in a large-scale irrigation system

Abstract Typically, large-scale irrigation systems are built almost entirely in a short time-frame, a significant part of the assets age at the same time and concentrated investment needs for rehabilitation are predictable. This paper focuses on planning these needs in an aggregated way, providing a big picture for the long term investment plan. A methodology for this purpose was developed and applied to a large-scale irrigation utility in Portugal. For such, the following steps were taken: (i) system breakdown by functional areas; (ii) infrastructure components disaggregation; (iii) diagnosis of the reference situation; (iv) evaluation of long-term alternatives for rehabilitation investment planning. The methodology is in line with the IAM approach recommended by IWA and the ISO55000 standards. In this paper, the specificities of this particular application, namely a proposal of irrigation component classes, and the studied alternatives, are presented. As an overall result, it was possible to indicate a path for economic sustainability without committing the infrastructure sustainability: it is based on gradual replacement of the assets reaching their useful life, combined with a constant rehabilitation rate. This paper is a contribution to an AM system for irrigation utilities, so alignment with IAM and the contribution to a broader IAM system is highlighted.

A study on improvement needs for the soil water balance

One critical problem confronting mankind today is how to manage the intensifying competition for water among expanding urban centres, traditional agricultural activities and in-stream water uses dictated by environmental concerns based solely on the soil water balance. In the agricultural sector, the prospects of increasing the gross cultivated area are limited by the dwindling number of economically attractive sites for large-scale irrigation and drainage systems whose correct evaluation depends on the understanding of groundwater movement in three dimensions. The failure of present systems, and inability of sustainable extraction from surface and groundwater sources may be attributed, essentially, to poor planning, design, management and development, as not much is known about groundwater flow systems. Each flow system has different chemical quality, path of travel, recharge area, as well as water age. To take full advantage of investment in agriculture, a major effort is required to modernize irrigation and drainage systems and to further develop appropriate management strategies compatible with financial and socio-economic trends, considering the functioning of groundwater components in the environment. This calls for a holistic approach to irrigation, drainage management, and monitoring if the aim is to increase food production, conserve water, prevent soil salinization and water logging, and to protect the environment. Sustainable development should be based on a full understanding of the relationship between the used water source and the environment. To tackle this challenge, there is a need to focus on the following issues: affordability with respect to the application of new technologies; procedures for integrated planning and management of irrigation and drainage systems; analysis to identify causes and effects constraining irrigation and drainage system performance; evapotranspiration and related calculation methods; estimation of crop water requirements; technologies for the design, construction, and modernization of irrigation and drainage systems; strategies to improve irrigation and drainage system efficiency; environmental impacts of irrigation and drainage systems and suitable measures for creating and maintaining sustainability. Institutional strengthening, proper financial assessment, capacity building, training and education actions are also required to achieve a successful on the soil water balance.

OPTICS

Lawns, also known as turf, cover an estimated 128,000 km 2 in North America alone, with landscape requirements representing 30% of freshwater consumed in the residential domain. With this consumption comes a large amount of environmental, economic, and social incentive to make turf irrigation systems as efficient as possible. Recent work introduced the concept of distributed control in irrigation systems, but existing control strategies either do not take advantage of the distributed control, or do not revise the strategy over time in response to collected data. In this work, we introduce OPTICS, a data-driven control strategy that self-improves over time, adapts to the local specific conditions and weather changes, and requires virtually no human input in both setup and maintenance providing a plug-and-play system that requires minimal pre-deployment efforts. In addition to substantial improvements in ease-of-use, we find across 4 weeks of large-scale irrigation system deployment that OPTICS improves system efficiency by 12.0% in comparison to industry best and 3.3% in comparison to academic state of the art. Despite using less water, OPTICS also was found to improve quality of service by a factor of 4.0× compared to industry best and 2.5× compared to academic state of the art.

Water, Geography, and Aksumite Civilization: The Southern Red Sea Archaeological Histories (SRSAH) Project Survey (2009–2016)

For at least four decades, archaeologists have identified irrigation as playing a potentially major role in the rise of Aksumite civilization. Based on a systematic survey covering the area between Aksum and Yeha (Ethiopia), Joseph Michels proposed that large-scale irrigation systems introduced from Southwest Arabia contributed to the rise of Yeha as a major center of Pre-Aksumite civilization. To evaluate spatial patterning of archaeological sites with respect to water availability, this paper reports on results from archaeological survey of a 100 km2 region surrounding Yeha conducted by the Southern Red Sea Archaeological Histories (SRSAH) Project from 2009 to 2016. The SRSAH Project recorded 84 sites dating from the Pre-Aksumite to the Post-Aksumite periods (c.800 BCE to 900 CE). No ancient irrigation systems were identified and results do not show a correlation between archaeological sites and water resources. This suggests that irrigation was less important than Michels contended and that rainfed agriculture, terraces, and small-scale irrigation comparable with practices evident in the region today were sufficient to sustain ancient populations.

Revisiting Telemetry in Pakistan’s Indus Basin Irrigation System

The Indus Basin Irrigation System (IBIS) lacks a system for measuring canal inflows, storages, and outflows that is trusted by all parties, transparent, and accessible. An earlier attempt for telemetering flows in the IBIS did not deliver. There is now renewed interest in revisiting telemetry in Pakistan’s IBIS at both national and provincial scales. These investments are typically approached with an emphasis on hardware procurement contracts. This paper describes the experience from field installations of flow measurement instruments and communication technology to make the case that canal flows can be measured at high frequency and displayed remotely to the stakeholders with minimal loss of data and lag time between measurement and display. The authors advocate rolling out the telemetry system across IBIS as a data as a service (DaaS) contract rather than as a hardware procurement contract. This research addresses a key issue of how such a DaaS contract can assure data quality, which is often a concern with such contracts. The research findings inform future telemetry investment decisions in large-scale irrigation systems, particularly the IBIS.

Hydraulic Balance Adjustment Analysis and Optimization Method of Farmland Water Conservancy Pipe Network

The hydraulic balance of farmland water conservancy pipe network is a common problem in the current large-scale farmland irrigation system. It is of great practical significance to study the different types of unsteady flow hydraulic calculations in farmland water pipe network for the safe and stable operation of farmland irrigation. In this paper, based on the characteristic’s method, the mathematical model of the unsteady flow for farmland water pipe network was established, and the boundary conditions of the constructed model and the processing method for calculating the time step were given. Then, the proposed model was verified by actual examples, and the unsteady flow process of the irrigation pipe network was also calculated and analysed. The research results show that the method of characteristics can better optimize the boundary problem of water pump, nozzle and t-branch pipe in the unsteady flow of farmland irrigation pipe network. After the valve is closed, the water hammer pressure will appear in the irrigation pipe network system and propagate inside. The water hammer pressure at the valve is the largest; the greater the distance from the closing valve, the smaller the water hammer pressure. When closing multiple valves at the same time, complex water superimposing of hammer wave occurs in the pipe network, and the maximum water hammer pressure after superimposing is much larger than the single valve closing. The longer the valve is closed, the smaller the maximum head pressure at the same monitoring point. The research conclusion can provide a theoretical reference for the engineering treatment of the unsteady flow in the farmland water conservancy pipe network.

Assessing the performance of a large-scale irrigation system by estimations of actual evapotranspiration obtained by Landsat satellite images resampled with cubic convolution

Remote sensing techniques allow monitoring the Earth surface and acquiring worthwhile information that can be used efficiently in agro-hydrological systems. Satellite images associated to computational models represent reliable resources to estimate actual evapotranspiration fluxes, ETa, based on surface energy balance. The knowledge of ETa and its spatial distribution is crucial for a broad range of applications at different scales, from fields to large irrigation districts. In single plots and/or in irrigation districts, linking water volumes delivered to the plots with the estimations of remote sensed ETa can have a great potential to develop new cost-effective indicators of irrigation performance, as well as to increase water use efficiency. With the aim to assess the irrigation system performance and the opportunities to save irrigation water resources at the “SAT Llano Verde” district in Albacete, Castilla-La Mancha (Spain), the Surface Energy Balance Algorithm for Land (SEBAL) was applied on cloud-free Landsat 5 Thematic Mapper (TM) images, processed by cubic convolution resampling method, for three irrigation seasons (May to September 2006, 2007 and 2008). The model allowed quantifying instantaneous, daily, monthly and seasonal ETa over the irrigation district. The comparison between monthly irrigation volumes distributed by each hydrant and the corresponding spatially averaged ETa, obtained by assuming an overall efficiency of irrigation network equal to 85%, allowed the assessment of the irrigation system performance for the area served by each hydrant, as well as for the whole irrigation district. It was observed that in all the investigated years, irrigation volumes applied monthly by farmers resulted generally higher than the corresponding evapotranspiration fluxes retrieved by SEBAL, with the exception of May, in which abundant rainfall occurred. When considering the entire irrigation seasons, it was demonstrated that a considerable amount of water could have been saved in the district, respectively equal to 26.2, 28.0 and 16.4% of the total water consumption evaluated in the three years.