Irrigation reliability and the productivity of water: A proposed methodology using evapotranspiration mapping

Irrigation is the dominant user of water worldwide, but provision of potable water and water for industry are higher priorities and give higher social and economic returns. Irrigation will continue to lose water to competing sectors and the productivity of irrigation systems (since food demand continues to grow) remains a central issue in water management. Performance assessment of irrigation has traditionally been difficult when based on field measurements of flows, deliveries and depths over large areas. Furthermore, performance measures have shifted from narrow engineering indicators to broader productivity issues of production achieved per unit of water consumed. Remote sensing, applied to the estimation of evapotranspiration (ET) over large areas, provides analysts of irrigation systems with extraordinary new tools for the objective assessment of consumption and production – constituting a quantum leap in the assessment of irrigation system performance. Awareness and utilisation of these tools is spreading, but important areas remain to be “converted” from traditional approaches that rely on an array of estimated parameters. The next challenge for remote sensing will be to map the frontier between the reliability of the irrigation service and the productivity achieved. Reliability provides the inducement for farmers to invest in higher productivity – to the benefit of themselves and society – and understanding better how the individual maximises profits within an uncertain irrigation environment can provide important guidance to managers and system designers.     

Low Cost Satellite Data for Monthly Irrigation Performance Monitoring: Benchmarks from Nilo Coelho, Brazil

Irrigation performance indicators can helpwater managers to understand how anirrigation scheme operates under actualcircumstances. The new contribution ofremote sensing data, is the opportunity tostudy the crop growing conditions at scalesranging from individual fields to schemelevel. Public domain internet satellitedata have been used to calculate actual andpotential crop evapotranspiration, soilmoisture and biomass growth on a monthlybasis in the Nilo Coelho irrigation scheme,Pernambuco (Brazil). Satellite interpretedraster maps were merged with vector maps ofthe irrigation water delivery system.Monthly values of a minimum list ofirrigation performance indicators for thevarious service units in the pressurizedNilo Coelho scheme were determined. NiloCoelho is a good performing scheme. Theperformance can be improved further if 25%irrigation water is saved from February toJuly. The benchmark figures from thismodern irrigation system are presented forcomparitive analysis with other systems.The acceptable ranges in space and timeare presented. On average, 65% of thelateral pumping units on a monthly basisfall within the acceptable limits ofirrigation performance. Low cost irrigationperformance data based on low resolutionsatellite images (US$ 1/ha) will help themanagement team to focus on specificpumping units, and discuss alternativeirrigation and farm management strategieswith the stakeholders.     

Temporal changes of irrigation system performance: development and test for a ratio of similar priority approach

Performance evaluation of irrigation systems is a key issue in the field of irrigation system management. This paper presents a Ratio of Similar Priority (RSP) method for irrigation systems performance evaluation. The time series data from the Shi-jin Irrigation District in northern China is used to test the method. The results show that this RSP method can be used to identify the main temporal changes of irrigation system performance. It offers clear and quantified results in terms of irrigation system performance evaluation.     

An economic analysis of irrigation systems

Summary An array of irrigation systems are available which can be broadly classified as being gravity flow or pressurized. Pressurized irrigation systems provide better control on the amount of applied water and, in most cases, better irrigation uniformity than gravity flow systems. They also have a higher initial capital cost than gravity flow systems and an analysis is required to determine whether the improved performance of pressurized systems justifies the additional costs. An economic analysis was done on several irrigation systems which included consideration of farm management costs associated with a given irrigation system, shifts in crop yield and drainage volumes associated with the optimal management of each irrigation system, and costs associated with disposal of drainage waters. Cotton was selected as the crop for analysis. Irrigation uniformity is a significant determinant to the results. Although irrigation uniformities can be highly variable based on design, maintenance and management, a typical uniformity for each irrigation system was selected. For the conditions of the analysis, gravity flow systems were calculated to be more profitable than pressurized systems if there was no constraint on the amount of drainage water generated or cost for its disposal. Imposition of costs for drainage water disposal induced a shift whereby pressurized systems became more profitable than gravity flow systems.     

Canal irrigation at night

Most canal irrigation water in South and Southeast Asia and elsewhere continues to flow at night and much is badly used or wasted. Yet what happens to water at night is a neglected subject, a matter for anecdotes more than analysis. Darkness, cold, fear, normal working hours, and desire for sleep deter irrigation staff, farmers and labourers from activities at night. At the farm level, irrigation at night entails extra labour and costs. It requires smaller streamflows and well shaped fields. Paddy and trees are the easiest crops to irrigate, and younger, lower and more thinly spread crops are usually easier than those which are older, taller and denser. On the lower parts of main systems, control at night often passes informally from irrigation staff to irrigators. Potential productivity of water at night is slightly raised by lower evaporation losses, but this gain is negligible compared with losses from breaks in channels, inefficient water application, and wasted water flowing into drains. Reuse of night drainage water lower down sometimes makes waste less wasteful than it appears. Equity effects at night are mixed: some farmers poach at the expense of others, but some get water at night who are denied it during the day. Night irrigation increases costs and inconvenience to small farmers, but raises labourers' incomes. Flooding and waterlogging can result from uncontrolled water flows at night.Practical implications are of two types: a)reducing irrigation at night, especially where water can be saved and stored by regulating releases from main reservoirs; in storage or by travelling in canals; by use of intermediate reservoirs; by pondage on-farm; or as groundwater. Care is needed in analysing what is waste and what is water saved. b)improving irrigation at night — by making flows predictable and manageable; by improving convenience and efficiency including lighting, ease of movement and field shaping; by choosing easy crops; by zoning for night flows; and by phasing for short nights, warmth and visibility. The potential for better performance on canal irrigation systems is probably large. It is hoped that this paper will encourage and provoke system managers, designers and researchers to explore the practical potential of this neglected subject about which much more needs to be known. Canal irrigation at night is too important to remain a blind spot any longer.B.C. Punmia & Pande Brij Basi Lal,Irrigation and Water Power Engineering, 7th ed., 1983, p. 48The magnitude of waste involved in not irrigating at night is so huge that savings from other sophistications in the field of water management like the lining of watercourses etc. pale into insignificance.S.P. Malhotra, 1983.Night irrigation and what we know about it is truly a blank page in our books.Gabriel J. Tibor, 1985.     

Combining remotely sensed surface energy fluxes and GIS analysis of groundwater parameters for irrigation system assessment

Despite being necessary for effective water management, the assessment of an irrigation system requires a large amount of input data for the estimation of related parameters and indicators, which are seldom measured in a regular and reliable manner. In this work, spatially distributed surface energy balance fluxes and geographical information systems analysis of multiple groundwater parameters were used to estimate water availability, supply, and demand, in order to calculate water-accounting indicators. This methodology was used to evaluate the performance of an irrigation system in the Pinios river basin (Greece) at two selected years of high and low water availability. Time series of archived satellite images and groundwater measurements have been used for past years to support comparative analyses, due to the limited availability of actual water measurements. The resulting maps from the proposed methodology show that the performance of the irrigation system varied across space and time due to differences in its characteristics and changes in its operation, driven by fluctuation of water availability and the response of stakeholders to water depletion. Irrigation districts with unsustainable water management were identified and, together with those with slow and/or limited groundwater recharge, were brought to the attention of water managers. The observed differences in the system operation between the wet and dry years were attributed not only to the hydrological conditions of each year, but also to the changing behaviour of farmers and the improvement actions of the water managers.     

基于实时气象信息的灌溉决策支持系统研究

基于实时气象信息的灌溉决策支持系统,是利用实时的气象信息结合灌溉预报模型,实现灌溉管理的自动化、智能化。详细介绍了基于实时气象信息的灌溉决策支持系统主要的数学模型、系统结构及功能。与现有的灌溉管理系统相比本系统在改进了灌溉计划的制订流程、增加了实时气象预报的灌溉计划修正功能,并提供智能的人工干预功能;此外,结合数据分析技术和灌溉管理的实际特点,利用回归分析方法解决由于极端天气或数据采集过程中引起的数据缺失及错误问题,提供灌溉决策的准确性。实际应用表明,系统具有较高的实用性和准确性,为灌区灌溉管理提供了科学手段及依据。     

Introducing monitoring and evaluation into main system management — a low investment approach

The need to develop a framework for performance assessment of irrigation schemes is increasingly dominating discussions in the field of water management. This paper supports the view that the introduction of monitoring and evaluation of water distribution systems as a part of the day to day management activity is a desirable step in the improvement process and can be introduced at little cost.Data already being routinely collected in many schemes provide a valuable insight into scheme operation and can be used to improve planning of operating strategies. One aim of the study being carried out by Hydraulics Research and the Irrigation Department at Hakwatuna Oya in Sri Lanka is to improve the standards of main system management within the constraints of the existing physical infrastructure through the provision of timely performance data. A microcomputer has been installed at the project office to store and analyse rainfall, flow and field wetness data, and to provide performance reports on a regular basis. Early results suggest that the timely processing of an increased level of data collection is effective for both the identification of problems and the quantification of potential for improvement. Particular emphasis is given to providing the necessary software tools and training such that routine monitoring and evaluation becomes an accepted and sustainable proposition.     

Diagnosing irrigation performance and water productivity through satellite remote sensing and secondary data in a large irrigation system of Pakistan

Irrigation policy makers and managers need information on the irrigation performance and productivity of water at various scales to devise appropriate water management strategies, in particular considering dwindling water availability, further threats from climate change, and continually rising population and food demand. In practice it is often difficult to access sufficient water supply and use data to determine crop water consumption and irrigation performance. Energy balance techniques using remote sensing data have been developed by various researchers over the last 20 years, and can be used as a tool to directly estimate actual evapotranspiration, i.e., water consumption. This study demonstrates how remote sensing-based estimates of water consumption and water stress combined with secondary agricultural production data can provide better estimates of irrigation performance, including water productivity, at a variety of scales than alternative options. A principle benefit of the described approach is that it allows identification of areas where agricultural performance is less than potential, thereby providing insights into where and how irrigation systems can be managed to improve overall performance and increase water productivity in a sustainable manner. To demonstrate the advantages, the approach was applied in Rechna Doab irrigation system of Pakistan’s Punjab Province. Remote sensing-based indicators reflecting equity, adequacy, reliability and water productivity were estimated. Inter- and intra-irrigation subdivision level variability in irrigation performance, associated factors and improvement possibilities are discussed.     

Methodologies for assessing performance of irrigation and drainage management

This paper presents a framework irrigation managers can use in assessing performance of irrigation, and recommends a specific set of indicators for measuring performance that the authors believe are practical, useful, and generally applicable. Although the primary focus is on the management of canal systems for agricultural production, the paper also discusses indicators that can be used for assessing longer term performance, including physical, economic and social sustainability. Finally, the paper highlights the crucial importance of strategic, as well as operational management performance, and the necessity of having an incentive system that encourages managers to improve performance.     

基于资产管理方法的灌区资产综合评价体系研究

加强灌区建筑物管理是实现灌区可持续发展的有效途径。将商业财务领域中的资产管理方法引入到灌溉系统管理中来,根据其基本原理建立了灌区资产综合评价体系,通过层次分析法和熵值法确定指标权重,对灌区资产的运行状况、水力性能、重要度等类别的不同指标进行综合评价,其评价结果可以作为决策支持信息确定资产更新改造的优先性,制定中长期的投资策略。以湖北省漳河灌区四干渠和二干渠为例,对其干渠沿线资产(水闸、涵管、渡槽、桥梁、泵站等5类)进行评价和对比分析。评价结果与灌区实际运行、管理情况基本一致。     

GIS user-interface based irrigation delivery performance assessment: a case study for Tanjung Karang rice irrigation scheme in Malaysia

Various indicators are used for evaluating the performance of different aspects of an irrigation system, and assessments also differ in terms of the types of performance indicators used. This paper describes a GIS-based assessment system which utilizes a new concept and evaluated the inadequacy of a widely used Relative Water Supply (RWS) concept to characterize the irrigation delivery performance for a rice irrigation system as the season advances. Development of this GIS-based assessment system resulted in the creation of new indicators, viz., the Rice Relative Water Supply (RRWS), Cumulative Rice Relative Water Supply (CRRWS) and Ponding Water Index (PWI). These indicators were determined from field tests and evaluated in a Malaysian Tanjung Karang Rice Irrigation Scheme (TAKRIS). The RWS concept was found to be inaccurate for characterizing the oversupply condition on irrigation deliveries for rice irrigation; and difficult to correctly quantify the oversupply condition for irrigation supplies. Besides, it was found that the RRWS indicator can distinctly characterize the oversupply condition for RRWS > 1.0 and undersupply condition for RRWS < 1.0 on irrigation delivery for any given period. A value of 1.0 for RRWS indicates an irrigation delivery that matches perfectly the actual field water demand. This study presents a cumulative RRWS plot that provides important information on irrigation supplies for any given time interval for management decisions. An increasing slope in the actual CRRWS curve with CRRWS = 1.0, means that irrigation supply can be slightly curtailed in the next period. On the other hand, if the slope is negative, supply has to be increased. If a computed CRRWS line follows the CRRWS = 1.0 line, it means that irrigation deliveries are perfectly matched with the field water demand. A graphical user-interface was developed for structuring the assessment tool within an ArcGIS platform. The system can instantly provide information on the uniformity of water distribution and the shortfall or excess, and provides vital information in terms of decisions that need to be made for the next period. The system helps to maintain continuous updating of input and output databases on real field conditions. Results are displayed on the computer screen together with color-coded maps, graphs and tables in a comprehensible form. The system is likely to be adopted for evaluating various water allocation scenarios and water management options. It can also be used as an analytical and operational tool for irrigation managers.     

Long-term water balances in La Violada Irrigation District (Spain): II. Analysis of irrigation performance

The analysis of long-term irrigation performance series is a valuable tool to improve irrigation management and efficiency. This work focuses in the assessment of irrigation performance indices along years 1995-2008, and the cause-effect relationships with irrigation modernization works taking place in the 4000 ha surface-irrigated La Violada Irrigation District (VID). Irrigation management was poor, as shown by the low mean seasonal irrigation consumptive use coefficient (ICUC = 51%) and the high relative water deficit (RWD = 20%) and drainage fraction (DRF = 54%). April had the poorest irrigation performance because corn (with low water demand in this month) was irrigated to promote its emergence, whereas winter grains (with high water demands in this month) were not fully irrigated in water-scarce years. Corn, highly sensitive to water stress, was the crop with best irrigation performance because it was preferentially irrigated to minimize yield losses. The construction of a new elevated canal that decreased seepage and drainage fractions, the entrance in operation of six internal reservoirs that would increase irrigation scheduling flexibility, and the on-going transformation from surface to sprinkler irrigation systems are critical changes in VID that should lead to improved ICUC, lower RWD and lower DRF. The implications of these modernization works on the conservation of water quantity and quality within and outside VID is further discussed.     

Regional allocation of irrigation water in a rice paddy area with water-saving practices

A multiobjective optimization model has been presented for allocating irrigation waters in a rice paddy area. Water-saving practices conducted on the field-plot basis are considered and expressed in the optimal water allocation problem in the regional scale. Irrigation water allocated to the blocks of paddy fields is divided into two components of a basic amount and a safety margin in order to mitigate the effect of hydrological and hydraulic uncertainties on the study area. Four competing management objectives with regard to total rice yield, total water-saving cost, equity of water allocation, and safety of water supply are defined in the linear programming formulation so that noninferior solutions can be procured which are informative and persuasive in decision-making. Applicability of the optimization model is examined using water allocation problems for a hypothetical irrigation system. It is demonstrated that the optimization model can provide satisficing solutions where the four objectives are harmonized under substantial variations of total water supply to the irrigation system.     

基层水利站工作经验初探

基层水利站工作经验初探陈维民，苏公伟（山东省水利厅农水处济南市２５００１３）（山东省兖州市谷村乡水利站２７２０１２）ＳｔｕｄｙｏｎＤｙｎａｍｉｃＷａｔｅｒＵｓｅＰｌａｎＤｒａｆｔｉｎｇｏｆＲｅｓｅｒｖｏｉｒＩｒｒｉｇａｔｏｉｎＳｃｈｅｍｅ￥ＬｉＹｕａ...     

Performance of agency-managed and farmer-managed irrigation systems: A comparative case study at Chitwan, Nepal

Management reforms are considered one of the best alternatives in increasing efficiency of the irrigation systems. Transfer of day-to-day operation and maintenance to farmers is not a new concept. However due to lags, even now it is a hot issue in developing countries and Nepal is not an exception. In this context of growing argument about the transfer of management of public irrigation systems to the Water Users' Group, this paper examines the comparative performance of farmer-managed and agency-managed irrigation systems. Khageri Irrigation System in the Chitwan district of Nepal was taken as the study site where complete management transfer has been done in 1996. The situations before and after complete transfer were compared. Intensive case studies of the selected farmers showed that equity in distribution of water and leakage had significantly improved after management transfer. Logit analysis revealed that age and education level of the household head, distance from main canal, leakage of the canal and equity in distribution are significantly related to the satisfaction level of the beneficiary farmers from FMIS compared to AMIS. However, landholding size of the respondent farmer has no significant effect. Similarly results from t-test revealed that rice productivity and overall profits from agriculture has also increased significantly due to irrigation management transfer.     

Increasing productivity in irrigated agriculture: Agronomic constraints and hydrological realities

Irrigation is widely criticised as a profligate and wasteful user of water, especially in watershort areas. Improvements to irrigation management are proposed as a way of increasing agricultural production and reducing the demand for water. The terminology for this debate is often flawed, failing to clarify the actual disposition of water used in irrigation into evaporation, transpiration, and return flows that may, depending on local conditions, be recoverable. Once the various flows are properly identified, the existing literature suggests that the scope for saving consumptive use of water through advanced irrigation technologies is often limited. Further, the interactions between evaporation and transpiration, and transpiration and crop yield are, once reasonable levels of agricultural practices are in place, largely linear—so that increases in yield are directly and linearly correlated with increases in the consumption of water. Opportunities to improve the performance of irrigation systems undoubtedly exist, but are increasingly difficult to achieve, and rarely of the magnitude suggested in popular debate.     

Irrigation water prices for farmer-managed irrigation systems in Tanzania: a case study of Lower Moshi irrigation scheme

A computer program model for pricing irrigation water among beneficiaries was developed and tested. The data used for the purpose was collected from Lower Moshi farmer-managed irrigation scheme (FMIS) in northern part of Tanzania as a case study. The scheme has two intakes; namely Rau and Mabogini irrigation systems. Allam's mathematical model for allocating irrigation water price which was developed in Egypt (Allam, 1987) was adopted and adapted for the purpose. The results indicate that the irrigation water price depends on a number of structures serving the area, their installation costs, amount of water received by each tertiary block and water rights. The prices differ between different tertiary blocks within the same system and also between two systems that exist in Lower Moshi Irrigation Scheme (LMIS). This indicates that the model can be used as a tool by designers and planners for selecting the best designed irrigation system that farmers can afford to pay for its operation, maintenance and management. The mean irrigation water price value for Mabogini is Tshs. 12 151/-¹ while that of the Rau system is 10 414/-. To maintain uniformity of irrigation water price in the scheme, it is recommended that a mean value of Tshs. 11 283/- is used. Generally, farmers in Tanzania are used to contribute one bag of paddy which costs about Tshs. 10 000/- for maintenance works. Therefore, the irrigation water price derived from the model is reasonable and one the farmers can afford.     

节水灌溉水稻高产优质成因分析

分析了宁夏引黄灌区控灌条件下水稻各生育阶段根系、茎杆、叶片、分蘖等生态指标和土壤肥力、土壤水分等土壤理化状况及水稻产量构成因素、稻米品质、水稻发病及倒伏指标。结果表明 :控灌水稻有显著的节水增产效果 ,水稻单产 1 0 3 98kg/hm2 ,增产幅度为 5.3 %,节约灌溉用水量 70 57.5m3/hm2 ,节水幅度达3 8.8%。稻米品质也相应提高 ,控灌水稻粗蛋白含量提高 0 .2 1 %,整精米率提高 1 .59%,垩白度和垩白率降低1 .1 2 %和 0 .2 9%。同时抗病虫害和抗倒伏能力提高 ,病株率降低 1 9.8%,病叶率降低 1 5.4 %,倒伏率降低1 8.3 %。控灌通过稻田水分的合理调控 ,改善了稻田根层土壤性状 ,促进了根系的生长发育 ,有效地协调了茎、蘖、叶、穗、粒的生长 ,形成较合理的群体结构和较理想的株型 ,茎杆粗壮抗倒伏 ,蘖叶早生快发 ,有效分蘖率高 ,叶面积指数增减过程合理 ,穗大 ,实粒多 ,千粒重高 ,品质好。实现了宁夏水稻在控灌条件下的节水高产优质     

胶东水库灌区果树灌溉效益分摊系数试验研究

在灌溉工程项目经济效益分析和评估中 ,通常应用灌溉效益分摊系数法 ,对粮食作物如冬小麦、夏玉米、水稻方面有一些研究成果 ,但对果树的灌溉效益分摊系数研究较少。山东省胶东地区是国内享有盛名的果树种植区 ,自然条件优越 ,果树种植面积大 ,效益高 ,产业化发展前景好 ,对果树生产效益方面的研究具有实际和很好的代表性。基于上述原因 ,龙口市北邢家水库所在其灌溉试验站对果树灌溉效益分摊系数进行 3年的试验研究 ,主要研究了长把梨、苹果、黄杏 3种主要果树的灌溉效益分摊系数 ,为灌溉水在果树生产中的作用作了定量分析 ,为灌溉工程的经济评价提供了科学依据。