Investing in irrigation: Reviewing the past and looking to the future

This article gives a brief review of the development and current situation in global irrigation, and looks at the drivers affecting irrigation performance, development and modernization. The article concludes that the options for new developments are limited, and that future investment will need to be more precisely targeted to specific niches in different agroecological and economic contexts. The paper notes the powerful implications of global climatic change on irrigation through changes in hydrology and water supply that, in conjunction with (1) continued demand for cheap food to satisfy continuously growing populations and changing dietary preferences (projected to 2050) and (2) increasing competition for high reliability water from higher value economic sectors, indicate irrigation performance and the productivity of agricultural water use must further improve, and are also likely to become more targeted at higher value enterprises. Improving management, through better institutions and better technology will require constant adaptation and finessing, with no silver bullets currently on the horizon.     

太阳能应用于节水灌溉发展现状与发展趋势

近些年来,太阳能作为一种新能源在农业中得到利用,基于太阳能的灌溉技术在世界各地迅速发展起来,尤其是基于太阳能供能的节水灌溉技术更是受到较大关注。高效、节能、低碳与环保是开展现代农业的前提与基础,是开展节水灌溉与太阳能技术相互结合的保证。围绕着国内外太阳能节水灌溉技术的发展现状等研究情况进行了阐述,指出了现有太阳能节水灌溉系统的特点,并在此基础上指出了我国发展太阳能节水灌溉的必要性,开发研制相应的人工智能—太阳能自动节水灌溉系统装置,并在实践中得到较好的应用是现阶段的主要研究方向。     

Landscape analysis: A design tool for sustainable irrigation development

By taking the proposed smallholder South-West Kano irrigation scheme as a case study, this article illustrates that designing sustainable irrigation schemes requires knowledge of the present landscape and insight into the demands of the society on the environment at present and in the future. First, the effects of irrigated rice production on farming households in four existing irrigation schemes in the Kano Plains in Kenya are evaluated. Second, a landscape analysis is applied to the South-West Kano project area to evaluate the uses and functions of the current landscape. The design criteria formulated from the perspective of these two evaluations form the basis of an assessment of four options of irrigation development in the South-West Kano project area. As socio-economic processes are reflected in the landscape, landscape analysis can be instrumental in visualizing and quantifying data not easily grasped otherwise. It may thus help to make discussions between farmers and engineers more concrete and to the point.     

Simulation of automatic control of an irrigation canal

Improved water management and efficient investment in the modernization of irrigation schemes are essential measures in many countries to satisfy the increasing demand for water. Automatic control of the main canals is one method for increasing the efficiency and flexibility of irrigation systems. In 2005, one canal in the irrigation scheme ‘Sector B-XII del Bajo Guadalquivir’ was monitored. This canal is representative of irrigation schemes in Southern Spain; it is divided into four pools and supplies an area of 5154 ha. Ultrasonic sensors and pressure transducers were used to record the gate opening and water levels at the upstream and downstream ends of each canal pool. Using the recorded data and the SIC (Simulation of Irrigation Canals) hydraulic model, two canal control options (local upstream control and distant downstream control) were evaluated using a PI (Proportional-Integral) control algorithm. First, the SIC model was calibrated and validated under steady-state conditions. Then the proportional and integral gains of the PI algorithm were calibrated. The controllers were tested using theoretical demand changes (constant outflow followed by a sudden demand increase or decrease) and real demand changes generated on the basis of a spatially distributed crop water balance that included a number of sources of variability (random and not random) in the determination of field irrigation timing and depth. The results obtained show that only the distant downstream controller was able to adjust quickly and automatically the canal dynamics to the varying water demands; it achieved this efficiently and with few spills at the canal tail, even when there were sudden and significant flow variations.     

基于时变非线性特征和状态变量的农田灌溉节水控制方法

常规的农田灌溉节水控制,主要采用影响因子分析模拟农田灌溉精度得出农田灌溉节水控制方案,忽略了实际农田土壤的液限和塑限变量对控制方案造成的影响,导致节水控制结果的节水系数较低。提出了基于时变非线性特征和状态变量的农田灌溉节水控制方法。该方法计算农田土壤的基础参数分析时变非线性特征,根据分析所得的特征计算约束条件,建立目标约束函数,构建出农田灌溉的节水控制模型,计算农田土壤液限和塑限的状态变量重新演化模型的目标约束条件,得出最终的农田灌溉节水控制方案。试验结果表明,所提方法应用后得出的节水控制结果,表现出节水系数较高,均值达到0.477,节水效果较好,满足农田灌溉的现实应用需求。     

国内外精密播种机监控系统的现状和发展趋势

介绍了精密播种机监控系统发展的三种基本形式，阐述了国内外发展现状，指出了监控系统存在的问题，并分析了监控系统将来的发展趋势。     

Model of the small scale dairying enterprise: An aid to resource allocation in agricultural development

A model of a smallholder dairying system in the high potential country in Kenya is briefly described. A sensitivity analysis was carried out with the model for two replacement policies and six herd sizes. The ensuing output of mean monthly milk yields and incomes was subjected to an analysis of variance where the major effects of four performance variables were ascertained. Response surfaces were fitted to the data generated from the model and were used to demonstrate that the relative income responses to an improvement in each variable dependend on the initial levels of performance.It is suggested that the technique reported here may be utilised as part of a larger cost-benefit analysis designed to assist in the allocation of resources for research and development aimed at improving the performance of smallholder dairy farmers. In addition, there is a need for greater involvement in extension research, so that the cost of obtaining an improvement at the farm level in a given performance variable can be estimated. Guidance of research and development priorities with respect to the smallholder dairy industry could then proceed in a more rational manner.     

Development of the irrigation M&O learning process

A learning process has been developed, based on experiences in Thailand, Sri Lanka and Nepal, for improving the maintenance and operations practices of an irrigation project or system. This learning process has been designed to:

minimize the investment (O&M) costs so as to avoid rehabilitation;

increase credibility of irrigation project staff with central headquarters through improved financial management practices and accountability; and

develop more knowledge about what is occurring within the system in order to meet the needs of farmers.

     

Influence of irrigation on the development and yield of potatoes

Verification of the model of potential yield developed by De Wit and modified by Rijtema, Feddes et al. and others, was carried out for two varieties of potato grown under different water and fertilization conditions. The anticipated yields were found to be correlated with the measured ones at the 0.99 confidence level, evidenced by correlation coefficients from 0.96 to 0.97. This means that for a given potato variety and under determined water and fertilization conditions the yield can be forecasted with the model.     

Water management in an ancestral irrigation system in southern Spain: a simulation analysis

The snow pack of Sierra Nevada, southern Spain, melts during spring and early summer, feeding ancestral irrigation channels in the region known as the Alpujarra. This simulation study compares the traditional irrigation water supply, based on proportional division, with the actual supply, based on up-downstream priority, in one watershed in the Alpujarra. A combination of three models was used for the analysis. Water supply was simulated using the snowmelt-runoff model. The snow cover required by that model was determined using satellite images. A second model simulated the distribution of water based on proportional division and on up-downstream priority. Irrigation requirements and return flows were simulated using a soil–water balance. Proportional division is an inherently equitable mechanism for distributing water, but can lead to water deficits for different crops in a command area. The analysis demonstrated this premise not be true. The superiority of proportional division was magnified in dry years. Because of the internal reuse of return flows, irrigation consumptive use coefficient (the ratio of irrigation water that is evapotranspirated by the crops to the total amount of irrigation water that leaves the area of concern during the period of analysis) at the watershed scale was significantly greater than at the irrigation-channel scale. This result illustrated, based on tradition in ancestral irrigation community, the notion of integrated water resources management.     

Application of automated flow and salinity control to dilution of saline irrigation water

Summary The utility of a saline water source for irrigation might, in many cases, be greatly increased if it could be diluted by mixing it with a higher quality source of water prior to field application. This paper discusses a number of options for achieving such a dilution subject to imposed constraints. Firstly, we derive and discuss the principles of achieving control of irrigation salinity level when waters of two different qualities and flow rates are used. Secondly, we formulate and discuss the dynamic performance of a prototype on a controlled dilution junction with and without water storage. Finally, we discuss the general problem of achieving simultaneous salinity and flow rate control, using dual feedback control sensors to compensate for variations both in salinity and in flow rate of the saline supply source in order to produce a desired salt concentration in the irrigation water.     

抓改革 促发展 实现灌区体制机制创新

1980年在漳河灌区衽的“按田配水、计量收费”灌溉管理制度改革试点，开始了湖北省理顺灌区管理体制的工作。目前，全省已建立了130余个农民用水者协会，并正在积极探讨和酝酿建立“公司＋协会”的管理模式。     

Reuse of drainage water in irrigation with the aid of 0-1 linear programming

Water management for irrigation in areas with high water scarcity includes not only domestic wastewater treatment but also practices for the reuse of drainage water during the irrigation period. The main problem that concerns the reuse of drainage water for irrigation is the accumulation of salts due to the effluents existing in the soil. In this paper an optimization technique is proposed for the management of drainage water that uses, in combination, a soil-water-plant model (SWAP) and a mixed 0-1 linear programming method. The optimization routine was applied to the irrigation network of Alfeios River in Western Greece, an area that is characterized by high precipitation imbalances between winter and summer months.     

自动化控制在滴灌工程中的应用

滴灌工程控制系统按照运行方式的不同可以分为三类,即手动控制、自动控制以及智能控制等.其中自动化系统的优点最为突出,所以针对大面积灌区而言,滴灌自动化控制系统比较适用.文章就针对滴灌工程中的自动控制系统的应用展开讨论.     

Economic analysis of rainwater harvesting and irrigation methods, with an example from China

The purpose of this paper is to evaluate the economic feasibility of agriculture with rainwater harvesting and supplemental irrigation in a semiarid region. The results show the importance of making full use of every open-air hardened surface to collect rainwater and to establish rainwater catchment areas by utilizing unoccupied land. The results also show that the usefulness of the harvested rainwater is enhanced when water saving and prevent seepage techniques are employed. The results indicate that in order to maximize investment it is essential to select crops with a water requirement process that coincides with local rainfall events. Potato was found to be the most suitable crop in the studied region. The economic indices for potato were superior to spring wheat, corn and wheat/corn intercropping. Therefore, potato production using rainwater harvesting and supplemental irrigation is the best alternative for cropping systems in the semiarid region of Gansu, China.     

水稻控水增产技术试验研究成果及其推广应用

水稻控水增产技术，是按作物需水要求严格控制田间水分，准确掌握控水时间和田间控水标准，使有限的水资源获得较高产量。１９９４～１９９８年零陵灌溉试验站主持，在湖南省８地市推广２５１．９万ｈｍ＾２次，获得了节水３０．３１％～５０．９１％，增产８．１６％～１４．３０％的效果。     

喷灌设备产品质量状况及对策分析

通过对铝合金喷灌设备中管道、水泵等产品质量、安全方面的分析，指出了存在的问题，并给出了相应的解决措施。     

The current and potential operational uses of remote sensing to aid decisions on drought exceptional circumstances in Australia: a review

This paper reviews how remote sensing is being used, and can be used, to assist in providing support for the decision-making process for the declaration of areas experiencing drought exceptional circumstances in Australia. To assess how remotely sensed data can be used, a review of current international uses of remotely sensed data was made and several topics requiring further research by remote sensing specialists identified. Consequently, the review focuses on current techniques used by Australian agencies, and also assesses current international methods, as well as proposing some possible new research directions that may use remote sensing for drought assessment and management. The primary scientific information that remote sensing can provide is the estimation of vegetation cover and condition, soil moisture, and the spatial limits to drought exceptional circumstances.     

The effects of partial root-zone irrigation and regulated deficit irrigation on the vegetative and reproductive development of field-grown Monastrell grapevines

The effects of regulated deficit irrigation (RDI) and partial root-zone irrigation (PRI) strategies that apply the same irrigation volumes on vegetative and reproductive development were analyzed during a 3-year-period in field-grown Monastrell grapevines under semiarid conditions. Five treatments were applied: control irrigated at 60?% ETc (crop evapotranspiration) for the whole season (308?mm?year^?1); RDI-1 and PRI-1 that received the same irrigation as the control before fruit set, 30?% ETc from fruit set to harvest and 45?% ETc post-harvest (192?mm?year^?1); and RDI-2 and PRI-2 that were the same, except with 15?% ETc from fruit set to harvest (142?mm?year^?1). Distinctive PRI effects on vegetative and reproductive development were observed depending on the total soil water content and the vine water stress level. PRI-1 vines showed less restriction of vegetative growth, lower leaf abscission, and higher leaf area during post-veraison than RDI-1 vines. Higher supply of water (close to field capacity) via half of the root system in PRI-1 vines maintained better water supply and more favorable phloem sap flow (water and carbohydrates) into the fruit during post-veraison and showed a positive differential effect on fruit growth compared with RDI-1 vines. This was reflected in a higher solute content per berry (12?% higher) and higher fresh berry weight (8?% higher) at harvest in PRI-1 compared to RDI-1 berries. However, this positive effect in fruit growth was not reflected in either an improved final yield or the water use efficiency of PRI-1 vines. In PRI-2, the soil water in the wet half was insufficient to maintain more favorable shoot water supply and phloem sap flow into the berry, and no substantial changes were observed in vine vigor, leaf and fruit growth between PRI-2 and RDI-2. Higher irrigation amount in the wet root zone and higher depth of irrigation under PRI seem to be more effective for 1103P–Mourvedre combination to produce a favorable effect in berry growth and development.