Application of the Analytic Hierarchy Process to irrigation project improvement: Part I. Impacts of irrigation project internal processes on crop yields

Performance improvement of existing irrigation projects has been a major concern in international irrigation development. Activities for irrigation project improvement usually involve not only infrastructure (hardware) improvement but also changes in management. However, the impact of management improvement on irrigation performance has not been sufficiently verified because, in most cases, (a) irrigation project evaluation is done qualitatively, and (b) management improvement is implemented simultaneously with hardware improvement. Therefore, the impact of management improvement needs to be evaluated quantitatively and separately from hardware. This research attempts to quantify effects of management and hardware improvements on irrigation project performance, using the Analytic Hierarchy Process (AHP). First, an AHP model for irrigation project evaluation was developed by using internal process indicators of the rapid appraisal process. Secondly, the AHP model was applied for scoring 16 irrigation projects dealt with in FAO Water Reports 19. Then, finally, effects of the evaluation factors (e.g. managing entities, hardware, water delivery services) on irrigation project performance were analyzed by changing weights of the evaluation factors and comparing correlations between AHP model scores and crop yields. The research showed the potential and effectiveness of AHP application to irrigation project evaluation. Also, it revealed that the quality of water delivery service had a significant impact on crop production. Analysis through correlation did not imply significant relationships among water delivery services, management and hardware. However, it is inferred from the result that there would be still more room to improve the AHP model toward better evaluation of the irrigation project by adding more internal process indicators to the model.     

Guilan,a successful irrigation project in Iran

This rapid appraisal study compares the actual and projected performance of a large, rice monoculture irrigation project in the humid climate of the Caspian Sea in Iran. The uniqueness of this project is the co-existence of East-Asia rice farming techniques with advanced technologies of automatic water control found generally in the Mediterranean countries. The paper emphasizes the need to do field tests at the design stage in order to make realistic assumptions on water efficiency and deep percolation. The study confirms that the advanced water control technologies are appropriate for small farm irrigation projects in the humid tropics, a conclusion often debated among experts. The Guilan project now provides some evidence to support that conclusion.     

Why invest in minor projects in sub-Saharan Africa? An exploration of the scale economy and diseconomy of irrigation projects

It is well-known that major irrigation projects have a strong scale economy, handicapping irrigation development in sub-Saharan Africa (SSA) because of the difficulty in formulating large-scale projects. Using project-level investment cost and performance data of major and minor irrigation projects, this paper examines the causes of the economy of scale phenomenon. We find that strong scale economy exists not only for major but also for minor projects, i.e., small- and micro-scale, projects. This is largely because of the existence of indivisible overhead costs such as high-opportunity-cost human resources for planning, designing and engineering management and supervision. We also find that large differences between major and minor projects in the absolute level of overhead as well as construction costs creates a strong scale diseconomy and results in better performance of minor projects. The advantage of minor projects holds even when their higher risk associated with the water source is taken into consideration. We argue that there is an urgent need to promote irrigation development in SSA through developing minor projects, and to reduce the heavy burden of overhead costs by developing the capacity of human resources at the national, local and farmer levels in the fields of irrigation engineering, irrigation agronomy, institutional development, and micro water management technologies.     

Review of irrigation system performance with respect to initial objectives

This paper presents the results of assessment studies of the performance of gravity irrigation projects, in six countries in different climate and social environments, with respect to their original objectives in terms of water availability, water use efficiencies, equity of water distribution, cropping intensity and crop yields, and project economic rates of return.An important lesson is the need for more realistic assumptions in the adoption of design standards, especially irrigation efficiency which affect the cropping intensity, the overall productivity of the project and its economic viability. This comparative method of performance assessment applied to a variety of projects has also provided some useful insights into the relative value of the different approaches to design of gravity irrigation systems.The views expressed in this paper are those of the author and are not presented as official views of the World Bank.     

Assessing irrigation projects performance for sustainable irrigation policy reform

This study examines the socio-economic and financial performances of irrigation projects under the Ogun-Oshun River Basin and Rural Development Authority (O-ORBRDA) in Nigeria. Primary data on the farming activities of the project farmers during the 2001/02 seasons and the projects' records for the period of 1995/96 to 2001/02 were summarised into socio-economic and financial performance indicators. In the Sepeteri Project, a revenue recovery level of 96% was estimated. The project is not financially viable as only 29% of its recurrent expenditure is covered. The farmers do not show commitment to making the project successful. An approximate 67% social capacity level was estimated. The relative irrigation cost and profit indexes do not show sufficient evidence that farmers would prefer irrigation farming to rain-fed farming. The Itoikin Project records a lower revenue recovery level of 75%. The project covers about 50% of its recurrent expenditure. In addition, the farmers do not appear to have a commitment to making the project successful, with a 33% social capacity level. A number of problems may be the causes of unprofitable irrigated cropping. If government increases the subvention, the O-ORBRDA prioritises irrigation service in disbursing the subvention to the projects, and the project manages the risks in the project sites, conscientises and incorporates the intended beneficiaries into managing the projects, the projects would be equipped to supply more irrigation services thereby making it more profitable and encouraging more participation of the intended beneficiaries. This would improve the socio-economic and financial performance of the projects.     

Performance analysis of public funded irrigation projects in Tanzania

Application of indicator-based management tools to evaluate performance and taking measures to mitigate the negative effects on project performance contributes to improvement. This research paper presents the findings of the analysis of performance of public funded smallholder irrigation projects in Tanzania with the aim to inform improvement actions. Through opinion survey of a sample of policy or decision makers and implementers of projects, and a case study of 16 smallholder irrigation projects, conceptual and physical data were collected and analyzed. The findings show that performance assessment in irrigation sub-sector in Tanzania is ad hoc, fragmented and done mainly during the construction phase, in donor funded projects. Seventy percent of 20 highly ranking performance indicators considered suitable in Tanzania also have high potential to improve project performance in the Tanzanian irrigation industry. These indicators constitute the key performance determinants. Forty percent of performance indicators currently used in Tanzania, which include the traditional time and cost indicators, are considered not significant in improving performance. Time and cost overrun of 16 investigated projects was in the tune of 50% and 8% respectively. The factors affecting project performance are diverse but interrelated, with possible common root causes, and effects cutting across various project processes. The mitigation measures are also interrelated and cut across project processes, and therefore, require integrative approaches.     

A rational method for assessing irrigation performance at farm level with the aid of fuzzy set theory

Of the various client groups with interests in irrigation system performance, farmers are probably the least often considered. This is, at least in part, attributable to the profound difficulty encountered in attempting to obtain reliable measurements of performance at farm level in most systems. Yet irrigation systems should be seen as a service to farmers, whose perspective on the utility of the supply is an important component of performance monitoring. Direct measurement at field level is generally not feasible and an alternative approach is proposed utilising fuzzy set theory. The procedure can be seen as a rapid appraisal technique which is also applicable to performance assessment in informal farmer-managed systems. The usefulness of the approach lies in its ability to gather data in imprecise linguistic terms from individual farmers and to aggregate them rationally and objectively.     

太阳能喷灌系统供给能源与水力性能关系

为了解决太阳能喷灌系统应用中无法对喷头水力性能进行有效预测的问题,以光照强度为影响因素,太阳能喷灌系统泵出口流量、泵出口压力、喷洒射程、水量分布及系统灌溉均匀性系数为评价指标,通过在夏季典型天气25~36℃下的系统水力性能试验,寻找不同光照强度下系统喷洒水力性能的变化规律,获得系统最佳工作状态下所需光照强度.试验结果表明:随着光照强度的增大,系统流量及泵出口压力均增大,泵的流量和压力随光照强度的变化规律基本符合指数分布规律.当光照强度大于900.0 W/m²时,系统流量、泵出口压力、射程及水量分布基本保持不变.获得了平均光照强度与均匀性系数函数关系,当光照强度大于900.0 W/m²时,系统喷灌均匀系数大于88%.当光照强度为200.0~600.0 W/m²时,系统喷灌均匀系数为76%~82%.太阳能喷灌系统在光照强度大于200.0 W/m²时可正常工作.该研究为改善太阳能喷灌系统水力性能,促进太阳能喷灌系统在实际工程中的推广应用提供了参考.     

微咸水灌溉动态安全评价理论及方法研究

针对灌溉水质、土壤安全、经济作物及荒漠植物安全等各项目标,结合灌溉制度、灌水方法、灌溉方式及土壤改良措施等动态因子,就微咸水资源化利用的安全性评价及其指标体系的建立进行了研究,确定了动态安全评价指标体系、评价方法及评价等级并编制了用于微咸水灌溉动态安全性评价的SASI软件。利用该软件对准噶尔盆地南缘莫索湾灌区微咸水农业灌溉的安全性进行了评价。评价结果表明该研究区域内,随着微咸水灌溉年份的增加,棉田土壤及作物虽然仍保持在未受污染的范围内,但污染指数逐渐增大,由此提出改善微咸水灌溉安全状况的措施及建议。     

A fuzzy multicriteria benefit-cost approach for irrigation projects evaluation

Three alternative irrigation projects for the East Macedonia-Thrace Region, Greece, are considered. Given the presence of valuable natural ecosystems in the area, environmental considerations are of great importance. In order to evaluate the projects, a fuzzy multicriteria benefit-cost approach is proposed. The overall goal is the rational management of water resources, and the projects appraisal is based on economic, social, and environmental criteria. Alternative scenarios on the availability of water resources are also incorporated in the decision model. The decision problem is formulated as two hierarchies, and the projects are ranked according to the benefit-cost ratio of their global priorities. The proposed method is proved to be, on the one hand, very suitable when both costs and benefits cannot be easily expressed into monetary terms as the traditional benefit-cost analysis requires; and, on the other hand, a valuable tool to cope with vague judgments.     

井灌区地下管道输水灌溉工程设计的研究

近几年来,井灌区地下管道输水灌溉(以下简称“管灌”)工程发展很快。保证“管灌”工程质量,发挥其应有效益,提高“管灌”工程设计水平非常必要。本文就井灌区地下硬塑管、混凝土管输水灌溉工程设计的依据、方法,水力计算,管径选择,设计灌溉面积等方面,从实际应用角度提出研究意见。     

基于粒子群算法的低压管灌系统水力计算方法

为了应对水资源危机,中国大力推广低压管灌技术用于粮食作物的灌溉.基于水量平衡和能量守恒原理,以系统的水量偏差最小为目标函数,支管的能量守恒和水量平衡作为约束条件,支管进口流量为决策变量,建立了低压管道输水灌溉系统的一维恒定流水力模拟模型,并相应地提出了试算-粒子群算法(TPSA)进行求解,可以获得系统实际运行时水泵的工况点以及各级管道和出水口的实际流量.将该方法应用于上海市一灌区的低压管灌系统,对比了TPSA与梯度法的求解结果,证明在同时工作的支管数较多的情况下TPSA可以获得更佳的求解结果,误差最多可减小12.3%,耗时最多可减少16.3%.应用该方法可以对管灌系统的初步设计成果进行校核和调整,对提高设计可靠性具有一定作用.     

贵州大型灌区续建配套与节水改造发展现状及对策研究

贵州省实施大型灌区续建配套与节水改造项目已有十余年,共有10个大型灌区列入全国规划。通过对大型灌区资料收集分析研究,划分灌区建设发展为三个阶段,并对大型灌区续建配套与节水改造的现状进行研究,包括灌区情况、投资概况、工程建设及效益、等内容,重点阐述灌区特点、存在的问题、发展思路及目标,并提出今后改造的建议及对策,为大型灌区今后发展作参考。     

Estimation of irrigation requirement for sustainable water resources reallocation in North China

The South-North Water Transfer (SNWT) project (upon completion) will deliver some 4.8 billion m³ of water per annum to Hebei, Beijing and Tianjin — greatly mitigating water shortage in North China. Surface water that is currently restricted to urban use could then become partly available for agricultural production. This will reduce the dependence of agriculture on groundwater, which will in turn retard groundwater depletion in the region. This study determines the spatial and temporal distributions of agricultural water requirement in Hebei Plain. This in turn lays the basis for surface water reallocation following the completion of the SNWT project. DSSAT and COTTON2K crop models are used along with crop coefficient methods to estimate required irrigation amounts for wheat, maize, cotton, vegetables and fruit trees in Hebei Plain. The study uses 20 years (1986-2006) of agronomic, hydrologic and climate data collected from 43 well-distributed stations across the plain. Based on the results, wheat accounts for over 40% of total irrigation water requirement in the plain. Similarly, wheat, maize and cotton together account for 64% of the total irrigation water requirement. The piedmont regions of Mount Taihang have the highest irrigation requirement due to high percent farm and irrigated land area. The months of April and May have the highest irrigation water requirement, respectively accounting for 18.1% and 25.4% of average annual irrigation. Spatial and temporal variations in our estimated irrigation water requirement are higher than those in the officially published statistics data. The higher variations in our results are more reflective of field conditions (e.g. precipitation, cropping pattern, irrigated land area, etc.). This therefore indicates a substantive improvement (in our study) over the average statistical data. Based on our simulation results, viable surface water reallocation strategies following the completion of the SNWT project are advanced and discussed.     

灌区农业干旱评估指标分析及应用

主要对三种农业干旱指标，即降水量指标、供需水关系指标和Palmer干旱指标进行评述，并对三种指标进行实例应用。应用结果表明，Palmer干旱指标可以更准确地评估灌区的干旱情况。根据分析结果建立了以Palmer指标为基础的灌区干旱评估模型。     

大中型灌区可持续发展评价方法研究

针对河南省典型大中型灌区,对灌区运行中的问题进行专家论证,结合区域持续发展评价理论提出灌区可持续发展评价指标体系,运用层次分析、德尔菲法建立评价模型并提出一种操作性较强的评价方法及其评价标准"三级评价值法"。使用该模型对河南省典型灌区进行了评价,取得了合理和较为满意的结果。     

Resource-centred thinking in river basins; should we revoke the crop water requirement approach to irrigation planning?

The paper examines the method of using project irrigation requirements (PIR) in the design and rehabilitation of small-scale smallholder irrigation systems within multi-sector and dynamic river basins. This procedure, which employs equations that determine irrigation and crop water requirements, is found embedded in irrigation thinking and planning methodologies throughout the irrigation world. The paper argues that if the PIR equations are used formally and conventionally without sufficiently accounting for changing demands for water in semi-arid river basins, they can lead to irrigation designs that over-prioritise water for individual irrigation systems and as such be labelled ‘irrigation-centred’. Although other adjustments and attempts at re-allocating water might be undertaken, basin managers are often unable to recognise, accommodate or transcend the irrigation focus that this approach generates thus curtailing the efficacy of re-allocation efforts. This argument is made on the basis of observations in the Usangu Plains of Tanzania of farmer-originated irrigation and donor attempts at rehabilitation and modernisation. Features of a modified planning and design methodology are suggested, which considers irrigation alongside other water sectors, and focuses on the river basin rather than on the individual system; an alternative which, it is proposed, is more flexible and ‘water-resource-centred’. The implications of this dualism in approaches (irrigation-centred or resource-centred) for basin management, livelihoods, conflict mediation and formal irrigation rehabilitation projects are explored.     

Soil management and traffic effects on infiltration of irrigation water applied using sprinklers

Zero tillage and controlled traffic have been proposed as means for more productive and sustainable irrigated farming. Both practices affect soil infiltration characteristics and, therefore, should have effects on sprinkler irrigation performance. This study compared water infiltration and runoff in three sprinkler irrigation tests performed on an alluvial loam soil at different times during a maize (Zea mays L.)–cotton (Gossypium hirstium L.) rotation under two soil managements: permanent beds with crop residue retention (PB: planting beds maintained unaltered from year to year) and conventional beds with residues incorporated with tillage (CB: disc and chisel ploughing followed by rotavator pass and bed forming every year). Traffic was controlled and two types of furrows were distinguished in both tillage systems: with (+T) and without (−T) wheel traffic. The irrigation tests were performed on maize at full cover, on bare soil just before cotton sowing and on cotton with 50% ground cover. Infiltration and runoff were affected notably by both traffic and soil management. The soil under PB infiltrated more water than under CB, and −T furrows more than +T furrows. Considering the combined treatments, −T furrows in the CB system infiltrated more water than +T furrows in the PB system. A sprinkler irrigation model for simulating water application and soil infiltration and runoff was formulated. The model was used to analyse irrigation performance under infiltration characteristic of the CB and PB systems in trafficked and non-trafficked furrows. Five irrigation performance indicators were used to assess the various combinations of tillage and traffic: Wilkox–Swailes coefficient of uniformity; application efficiency; deep percolation ratio; tail water ratio; and adequacy. The model was used to develop operation diagrams and provided guidelines for making irrigation decisions in the new controlled traffic/permanent bed system and in a standard conventional system.     

Tank performance and multiple uses in Tamil Nadu,South India–comparison of 2 time periods (1996–97 and 2009–10)

Irrigation tanks in India are common property resources. Tanks provide not only for irrigation, but also forestry, fishing, domestic water supply, livestock, and other uses. Using empirical results from a study of tank performance from 80 tanks in Tamil Nadu, South India in two time period: 1996-97 and 2009-10, this paper evaluates tank irrigation system performance in terms of economic output and revenue generation forirrigation and other uses. The results indicate that irrigation and other productive uses put together raised the total value of output at tank level by 12 % in 1996-97 and just 6 % in 2009-10. This may suggest that tank multiple use values are small and getting smaller, and therefore not worth consideration. However, it was also found that, while declining in absolute terms, non-irrigation uses provided the majority of tax revenues and still more than cover government's operation and maintenance expenditure (O&M) budget. This finding provides another reason to consider multiple use values and their linkage with overall system viability.