农田灌溉方式的经济学透视

农田灌溉方式正在由传统的大水漫灌向节水灌溉发展，从经济学的角度，运用成本与效益理论对传统农田灌溉方式向节水灌溉方式迈进的必然性做了定性分析，并提出推进节水灌溉进一步发展的措施：第一，加大资金投入力度；第二，科学管理用水；第三，确定一个有利于节约用水的水价。     

农田灌溉过程中的水力学问题

基于多年节水灌溉工程技术与产品的研发实践,提出发展灌溉水力学的初步设想.在分析农田灌溉实施过程的基础上,将其划分为输水、灌水、土壤入渗与植物吸水4个阶段;输水与灌水过程属灌溉水力学范畴,土壤入渗属土壤物理学范畴,植物吸水则与植物水分生理密切相关;灌溉水力学、土壤物理学与植物水分生理学共同构成农田灌溉的基本科学理论.据此给出了灌溉水力学的基本概念、研究对象与研究方法.灌溉水力学将着重研究输水与灌水过程中的水流运动规律,其科学目标是如何经济、高效、均匀地将灌溉水流输送到田间土壤;灌溉水力学的内涵主要包括灌溉水流运动规律、灌溉系统水力计算和灌溉均匀度评价3个方面.灌溉水力学的发展,可作为农田灌溉基本科学理论,指导灌溉技术和产品的研究与开发,为灌溉工程设计提供新方法和新手段.     

20年农田灌溉科技发展回顾

改革开放２０年来，在邓小平同志建设在中国特色社会主义理论的指导下，农田灌溉科学技术取得了举世瞩目的成就。文章从农田灌溉科技事业，农田灌溉的基础理论研究，高效井灌技术，节水灌溉研究示范与推广，农业水管理体制，农田水管理６个方面对２０年农田灌溉科学技术的成就作了回顾。     

20年农田灌溉科技发展回顾

改革开放２０年来,在邓小平同志建设有中国特色社会主义理论的指导下,农田灌溉科学技术取得了举世瞩目的成就。文章从农田灌溉科技事业、农田灌溉的基础理论研究、高效井灌技术、节水灌溉研究示范与推广、农业水管理体制、农田水管理６个方面对２０年农田灌溉科学技术的成就作了回顾     

对节水灌溉的再思考

华北地区农田灌溉的节水潜力问题,在“七五”期间对其研究过程中存在着两种截然不同的观点。一种观点认为灌溉水资源在地区内利用率已相当高,节水潜力有限,另一种观点认为由于灌区内的设施年久失修,灌溉输水过程中存在着严重的水量损失现象,且灌水定额控制不严,大水漫灌时有发生,因此农田灌溉节水大有潜力可挖。本文通过对节水潜力进行分析,初步提出了农田灌溉节水潜力的计算方法,指出了节水措施的有限性和制定节水灌溉措施规划的重要性。文章最后提出了当前急需认真研究的与此有关的几个问题,并就这些问题谈了自已的看法。     

农田灌溉节能节水智能控制系统的研究

介绍了农田灌溉节能节水智能控制系统的设计原理,提出了电动机带载软起动和软停止控制、末端无功补偿控制、IC卡预付费多用户三相电能计量管理;设计出了集控制、补偿、管理于一体的新型灌溉控制系统;该系统通过电动机的平滑软起动解决水锤问题,利用低压电能无功补偿实现节能控制,利用预付费多用户三相电能计量实现谁插卡谁灌溉的节水管理。具有平滑起停、节能节水和低成本的特点,特别适合于农田灌溉控制和管理。     

新日寸期我国节水灌溉发展战略与对策思考

根据中央一号文件和中央水利工作会提出要把节水灌溉作为一项战略性、根本性措施来抓的要求,强调了灌溉排水发展是保障国家粮食安全的基石;分析了农业、节水灌溉的发展趋势和节水灌溉的发展潜力;预测了我国农田灌溉可能的发展规模;指出今后一个时期节水灌溉发展战略是要从现代农业发展的视角定位和布局,要以水资源可持续利用确定节水灌溉工程...     

几种基于植物生理活动的节水灌溉指标研究进展

根据作物自身生理活动来确定合理的灌溉指标是节水农业研究的一个重要基础工作.近年来,伴随着植物生理学的发展,出现了几种非常有应用潜力的灌溉指标.对这几种指标的原理、研究现状及存在问题进行了评述,旨在推动作物节水灌溉指标的研究,从而建立更为合理的节水灌溉制度.     

多功能节水灌溉技术研究及应用

针对目前苏南地区传统的农田灌溉模式不适应当前现代农业生产发展要求的问题,提出了多功能节水灌溉理念,并在抽水站的形式、管网布局和农田放水口等3个方面进行了技术研究。太仓市何桥村节水灌溉示范区应用了多功能节水灌溉技术后.取得了良好的社会效益和经济效益。     

农田灌溉遥感监测技术的发展与前景北大核心

农田灌溉遥感监测旨在通过遥感技术监测灌区作物的灌溉面积和种植结构,来实施高效的灌溉用水管理,达到建设节水型农业和对灌区现代化管理的目的。科学客观地总结农田灌溉面积遥感提取相关的研究进展,能为开展该方面的研究提供一定的参考。通过系统全面的查阅国内外相关文献资料,总结当前研究所采用的原理与方法,具体操作过程,存在问题等,并对未来发展趋势进行了展望。值得肯定的是,目前已具有初步的理论和探索,对局部和区域农田灌溉面积的遥感提取具有了一定成效。不足之处在于,基于灌溉前后土壤水分和温度变化的原理与方法受降水影响大;地表实测数据收集困难;数据源单一,高"时空"分辨率数据少。在未来研究中,农田灌溉面积的多时相动态提取是趋势所在。还应注重以下几个方面:①提取原理和方法需进一步完善和补充;②注重多源数据和多种因素整合分析;③注重灌区基础资料库的建立和更新,注重大数据技术的应用。     

Economic analysis of integrated on-farm drainage management

The goal of integrated on-farm drainage management (IFDM) is to eliminate the discharge of subsurface drainage water from farms into waterways or evaporation ponds. Components of a typical IFDM system include improved irrigation practices, irrigation of salt-tolerant plants with drainage water, and on-farm disposal of drainage water using a solar evaporator. Costs of an IFDM system include initial investments, operation and maintenance, and the opportunity costs of land used for the solar evaporator and for irrigation of nonmarketable, salt-tolerant plants. The farm-level cost of an IFDM system increases with the proportion of farmland used to irrigate salt-tolerant plants. A conceptual framework for evaluating the farm-level costs of IFDM is presented, along with empirical analysis from California’s San Joaquin Valley.     

Higher performance through combined improvements in irrigation methods and scheduling: a discussion

Prior to the discussion on approaches to combine irrigation scheduling and water application practices, several farm irrigation performance indicators are defined and analysed. These indicators concern the uniformity of water distribution along an irrigated field and the efficiency of on-farm water application. Then, the analysis focus is on three main irrigation systems: surface, sprinkler and microirrigation. For each of these systems, the analysis concerns the main characteristics and constraints of the systems, more relevant aspects influencing irrigation performances, and approaches which could lead to a more appropriate coupling of irrigation scheduling and water application methods. Conclusions point out on the need for combined improvements in irrigation scheduling and methods, for expanding field evaluation of irrigation in farmers fields, for improved design of on-farm systems, and for quality control of irrigation equipments and design.     

Aflaj irrigation and on-farm water management in northern Oman

This paper reports on results from a case study on water management within a traditional, falaj irrigation system in northern Oman. In the planning and design of regional irrigation development programs, generalized assumptions are frequently made as to the efficiency of traditional surface irrigation systems. Although qualitative accounts abound, very little quantitative research has been conducted on on-farm water management within falaj systems. Daily irrigation applications and crop water use was monitored during an 11-month period among 6 farm holdings at Falaj Hageer in Wilayat Al-Awabi. Contrary to the frequent assumptions that all surface irrigation systems incur unnecessarily high water losses, on-farm ratios of crop water demand to irrigation supply were found to be relatively high. Based on actual crop water use, irrigation demand/supply ratios among monitored farms varied from 0.60 to 0.98, with a mean of 0.79. Examination of the soil moisture budget indicates that during most irrigations of wheat (cultivated in the low evapotranspiration months of October–March) sufficient water is applied for the shallow root zone to attain field capacity. With the exception of temporary periods of high falaj delivery flows or periods of rainfall, field capacity is usually not attained during irrigations within the more extensive root zones of date palm farms. The data presented in this paper should provide a better understanding of water use performance by farmers within traditional falaj systems. Moreover, these data should also serve to facilitate more effective development planning for irrigation water conservation programs in the region.     

Economic and agronomic strategies to achieve sustainable irrigation

The achievement of sustainable irrigation in arid regions requires greater attention to waterlogging, salinization, and degradation of ground and surface waters, which are among the problems that continue to threaten productivity and degrade environmental quality. We consider sustainability to be achieved when irrigation and drainage are conducted on-farm, and within irrigation districts, in a manner that does not degrade the quality of land, water, and other natural resources, either on-farm or throughout an irrigated region. Sustainability may also be described as maintaining the productive resources required for irrigation, so that future generations may have the same opportunity to use those resources as we do. Given the increasing importance of irrigated land for food production, the time has come when it is vital to intercept, reuse, and isolate drainage waters within the regions in which they are generated. Adoption of this strategy can be enhanced by policies that require farmers, and irrigation districts, to consider the off-farm impacts of irrigation and drainage. Such policies include linking water rights with salt rights to require the monitoring and management of both irrigation water and the salt loads in drainage waters. We review the knowledge gained since the early 1970s regarding the economic and agronomic aspects of irrigation and drainage, with a focus on drainage water reduction and sequential reuse of drainage water on salt-tolerant crops. Economic incentives that motivate farm-level and district-level improvements in water management are also reviewed. We conclude that adequate knowledge exists for implementing strategies that focus on water use and salt disposal within irrigated regions, and we recommend policies that will motivate improvements in productivity and enhance the likelihood of achieving sustainability.     

Economic evaluation of salinity,drainage and non-uniformity of infiltrated irrigation water

Salinity, drainage and non-uniformity of irrigation water are important components in determining optimal water application and related profitability. A crop-water production function assuming steady state conditions is incorporated in a long-run economic model to investigate the combined effects of salinity, irrigation uniformity and different drainage requirements at the field scale for the specific crop.The analysis was conducted for corn and cotton as sensitive and tolerant crops to salinity, respectively. Optimum applied water and associated profits, yield and drainage volumes were computed for each crop. The computations were done for the condition that no drainage system was required and also where a drainage system was required and the drainage water was disposed of to either a free off-farm facility or to an on-farm evaporation pond constructed on productive or non-productive land.The main findings are that type of drainage disposal system affects the optimal values of applied water, profits, yield and drainage volumes, except for uniform water applications and non-saline irrigation water. Another finding is that in the long run, under saline conditions and/or different drainage disposal systems, a sensitive crop such as corn is not profitable and goes out of production. In general the profit levels associated with the various drainage options are in the order of no drainage requirement ? free off-farm facility > on-farm evaporation pond on non-productive land > on-farm evaporation pond on productive land. Uniformity of irrigation water affects values of the analyzed variables and the effects are greatest for the cases of on-farm evaporation ponds. Pumping cost effects are quite small, but water price effects are more significant. Breeding the crops for increased salinity tolerance has little effect when irrigating with water of low salinity and/or low irrigation uniformity.     

Water productivity in rainfed systems: overview of challenges and analysis of opportunities in water scarcity prone savannahs

Addressing the Millennium Development Goals on food and poverty over the coming decade puts enormous pressure on the world’s finite freshwater resources. Without water productivity (WP) gains, the additional freshwater in agriculture will amount to 5,600 km³ year⁻¹ in 2050. This is three times the current global irrigation use. This paper focuses on the underlying processes and future opportunities of WP gains in water scarcity prone and poverty stricken savannah regions of the world. The paper studies the consumptive (green) WP dynamics rainfed farming systems, and shows that the often assumed linear relationship between evapotranspiration (ET) and yield (Y) does not translate into constant WP over a wide range of yields. Similarly, crop transpiration (T) and Y show non-linearity under on-farm and low yield conditions. This non-linearity is validated against several on-farm research experiments in semi-arid rainfed farming systems. With integrated soil and water management, focusing on dry spell mitigation and soil fertility can potentially more than double on-farm yields, while simultaneously improve green (ET) WP and productive green (T) WP. Through the adoption of appropriate soil and water management in semi-arid smallholder farming systems, crop yields improve and result in improved livelihoods and WP gains.     

新疆灌溉农业发展与节水潜力分析

分析了新疆灌溉农业的大发展及取得的成就，针对经济社会可持续发展对水资源有续利用的客观要求，对农业灌区的节水现状进行了探讨，并从地表水资源可利用量、输水系统节水潜力、平原水库增蓄水潜力及田间灌溉节水潜力等方面对灌溉用水的节水潜力问题进行了较全面的分析和研究。     

A review of irrigation performance assessment in California

A survey of irrigation performance assessment as conducted in California was performed. Emphasis was placed on the actual procedures employed by the State's major water providers and irrigation districts. Survey results covered the development of innovative irrigation performance assessment parameters as well as the methodologies used to evaluate these parameters. All aspects of California's irrigation infrastructure were considered, from the management of major hydraulic structures, through water delivery, and on-farm consideration. Environmental performance assessment methodologies were also examined.     

Irrigation management under water scarcity

The use of water for agricultural production in water scarcity regions requires innovative and sustainable research, and an appropriate transfer of technologies. This paper discusses some of these aspects, mainly relative to on-farm irrigation management including the use of treated wastewater and saline waters. First, the paper proposes some concepts relative to water scarcity, concerning aridity, drought, desertification and water shortage, as well as policies to cope with these water stressed regimes. Conceptual approaches on irrigation performances, water use and water savings are reviewed in a wide perspective. This is followed by a discussion of supply management to cope with water scarcity, giving particular attention to the use of wastewater and low-quality waters, including the respective impacts on health and the environment as water scarcity is requiring that waters of inferior quality be increasingly used for irrigation. The paper then focuses on demand management, starting with aspects relating to the improvement of irrigation methods and the respective performances, mainly the distribution uniformity (DU) as a fundamental tool to reduce the demand for water at the farm level, and to control the negative environmental impacts of over-irrigation, including salt stressed areas. Discussions are supported by recent research results. The suitability of irrigation methods for using treated wastewaters and saline waters is analysed. Supplemental irrigation (SI) and deficit irrigation strategies are also discussed, including limitations on the applicability of related practices. The paper also identifies the need to adopt emerging technologies for water management as well as to develop appropriate methodologies for the analysis of social, economic, and environmental benefits of improved irrigation management.