Flexible Irrigation Systems: Concept, Design, and Application

This paper presents the need, value, and concept of flexible irrigation water supply systems that can deliver water with flexibility in frequency, rate, and duration under the control of the farmer at the point of application using a limited rate arranged-demand or other schedule. It introduces the needed terminology including “congestion”—how much reserve time and capacity is required to assure water delivery at the frequency and rate desired. An illustrative design procedure for the necessary pipeline and reservoir capacities is illustrated. The techniques discussed emphasize the conversion of the economical steady supply canal flows to flexible on-farm usage through the use of service area reservoirs located between the secondary and tertiary systems, and of semiclosed pipelines and/or level-top canals as automated distribution systems which facilitates the farmers’ need for daytime only variable on-farm deliveries to permit optimization of on-farm water management. This improved management is the ultimate source of increased food production after improved crop, land, and water resources have reached their maximum. The coordinated use of return flow systems is described.     

Operational Cost Benefits Study of Flexible On-Farm Irrigation Supply Systems

Efficient on-farm use of water and labor for all methods requires a water supply flexible in frequency, rate, and duration and under the control of the irrigator at the point of application. For surface irrigation, the use of large capacity systems for supply and distribution are essential and economical, especially when considering the reduced labor needs, increased irrigation efficiency, and reduced potential high water table problems resulting from having a large, flexible supply associated with a flexible arranged-demand schedule. Automation and stability of flow at the farm turnout, comparable to a domestic system with variable flow delivery conditions, are typically accomplished by use of large capacity semiclosed pipeline systems. A cost comparison of capital investment for various sized, flexible supply systems with resulting farm water and labor costs is presented which shows the great value from the upgraded management made possible.     

Long-Term Operation of Irrigation Dams Considering Variable Demands: Case Study of Zayandeh-rud Reservoir, Iran

Dependency of water demands on the climate variation occurs especially in regions where agricultural demand has a significant share of the total water demands. The variability between demands that are based on annual climate conditions may be larger than the uncertainty associated with other explanatory variables in long-term operation of an irrigation dam. This paper illustrates certain benefits of using variable demands for long-term reservoir operation to help manage water resources system in Zayandeh-rud river basin in Iran. A regional optimal allocation of water among different crops and irrigation units is developed. The optimal allocation model is coupled with a reservoir operating model, which is developed based on the certain hedgings that deals with the available water and the water demands mutually. This coupled model is able to activate restrictions on allocating water to agricultural demands considering variation of inflow to the reservoir, variation of demands, and the economic value of allocating water among different crops and irrigation units. Using this model, long-term operation of Zayandeh-rud dam is evaluated considering different scenarios of inflow to the reservoir as well as agricultural demands. The results indicate that the use of operating rules which consider variable demands could significantly improve the efficiency of a water resources system in long-term operation, as it improves the benefit of Zayandeh-rud reservoir operation in comparison with conventional water supply approaches.     

Performance-Based Optimization of Land and Water Resources within Irrigation Schemes. I: Method

Optimum land and water allocation to different crops grown in different regions of an irrigation scheme is a complex process, especially when these irrigation schemes are characterized by different soils and environment and by a large network of canals. At the same time if the water supply in the irrigation schemes is limited, there is a need to allocate water both efficiently and equitably. This paper describes the approach to include both productivity (efficiency) and equity in the allocation process and to develop the allocation plans for optimum productivity and/or maximum equity for such irrigation schemes. The approach presented in this paper considers the different dimensions of equity such as water distribution over the season, water distribution during each irrigation, and benefits generated. It also includes distribution and conveyance losses while allocating water equitably to different allocation units. This paper explains the approach with the help of the area and water allocation model which uses the simulation–optimization technique for optimum allocation of land and water resources to different crops grown in different allocation units of the irrigation scheme.     

Simulating Water Management and Supply Effects at the Office du Niger Collective Canal Irrigation Scheme

This paper demonstrated how a modeling approach can be used to find the optimal mix of farmers’ water management practices to improve irrigation efficiency at the tertiary level in collective canal schemes. The approach is developed for the case of the Office du Niger and based on a field study of 3?years. First, a simulation model is presented in which all relevant physical and social aspects of water management at the farmers’ level are considered. Next, simulations are performed to evaluate the impact on performance of different combinations of management practices and different external conditions. Finally, the combinations are selected that succeed in limiting seasonal water consumption to 1,400?mm and avoiding irrigation problems, but which are also realistic from a farmer’s point of view. Results demonstrate that in the Office du Niger, where seasonal water consumption per hectare should be reduced by about 30%, a tight control of the tertiary intake in combination with a good maintenance of the tertiary canal should be proposed. Although the model software is built especially for the case of the Office du Niger, the concept of the model can be transferred to other irrigation schemes, as it uses only simple hydraulic principles and limited data input.     

A Paradigm Shift in Irrigation Management

In coming decades, irrigated agriculture will be called upon to produce up to two thirds of the increased food supply needed by an expanding world population. But the increasing dependence on irrigation will coincide with accelerating competition for water and rising concern about the environmental effects of irrigation. These converging pressures will force irrigators to reconsider what is perhaps the most fundamental precept of conventional irrigation practice; that crop water demands should be satisfied in order to achieve maximum crop yields per unit of land. Ultimately, irrigated agriculture will need to adopt a new management paradigm based on an economic objective—the maximization of net benefits—rather than the biological objective of maximizing yields. Irrigation to meet crop water demand is a relatively simple and clearly defined problem with a singular objective. Irrigation to maximize benefits is a substantially more complex and challenging problem. Identifying optimum irrigation strategies will require more detailed models of the relationships between applied water, crop production, and irrigation efficiency. Economic factors, particularly the opportunity costs of water, will need to be explicitly incorporated into the analysis. In some cases the analysis may involve multi-objective optimization. The increased complexity of the analysis will necessitate the use of more sophisticated analytical tools. This paper examines the underlying logic of this alternative approach to irrigation management, explores the factors that will compel its adoption, and examines its economic and environmental implications. Two important concerns, sustainability and risk, are discussed in some depth. Operational practices for implementing the new approach are contrasted with current, conventional irrigation practices. Some of the analytical tools that might be employed in the search for optimum irrigation strategies are reviewed. Finally, the limited and largely intuitive efforts that have already been made to implement this new paradigm are discussed.     

降低企业供水系统能耗的措施

通过对企业供水系统和能源消耗的调研分析,提出了合理优化供水系统、降低能源消耗的技术措施。实施后不仅提高了水资源的有效利用率,而且进一步提高了供水系统的保障能力,取得了良好的经济和社会效益。     

Multilevel Approach for Optimizing Land and Water Resources and Irrigation Deliveries for Tertiary Units in Large Irrigation Schemes. II: Application

The resource allocation model, area and water allocation model, incorporates the concept of deficit irrigation through a variable depth irrigation approach, VDI. It uses this to allocate land and water resources optimally to different crops in a heterogeneous irrigation scheme with limited water under rotational water supply. This model was applied to a medium irrigation scheme in India as a case study, to obtain the land and water allocation plans. These optimal allocation plans were compared to those obtained by using the model with the existing approach (full irrigation with a fixed irrigation interval of 21 days in Rabi and 14 days in the summer season). The allocation plans were obtained taking into account the different parameters that were included in the model, such as crops and cropping pattern, soils, irrigation interval, initial reservoir storage volumes, efficiencies, and the outlet and canal capacities. The total net benefits were compared for the two cases of fixed cropping distribution and free cropping distribution and a sensitivity analysis was conducted on other parameters. Summaries of the allocation plans with the VDI approach are presented for the two cases. The total net benefits obtained with the VDI approach introduced in the model were found to be 22% higher than those obtained with the existing approach. The results of this study are thus indicative of the benefits of deficit irrigation and its application within irrigation schemes that have limited water supply.     

浅谈建筑给排水环保节能的紧迫性及措施

随着我国正在大力提倡建立资源节约型社会,建筑给排水的节水节能设计有着显著的社会和经济效益,本文就是通过节水节能重要性提出了建筑给排水的具体措施。     

株洲硬质合金厂供水系统的节能措施

本详细地介绍了株洲硬质合金厂供、用水系统中采取的节能措施和取得的经济效益。     

狠抓脱硅乏气攻关 有铲降低蒸汽消耗

本文介绍了贵州铝厂氧化铝厂烧结法脱硅乏汽系统的流程改造,有效利用了脱硅乏汽加热沉降洗涤工序用热水和种分母液,解决了脱硅缓冲槽飘碱难题,社会效益和经济效益显著。     

Integrated Water Management for the 21st Century: Problems and Solutions

Most of the projected global population increases will take place in third world countries that already suffer from water, food, and health problems. Increasingly, the various water uses (municipal, industrial, and agricultural) must be coordinated with, and integrated into, the overall water management of the region. Sustainability, public health, environmental protection, and economics are key factors. More storage of water behind dams and especially in aquifers via artificial recharge is necessary to save water in times of water surplus for use in times of water shortage. Municipal wastewater can be an important water resource but its use must be carefully planned and regulated to prevent adverse health effects and, in the case of irrigation, undue contamination of groundwater. While almost all liquid fresh water of the planet occurs underground as groundwater, its long-term suitability as a source of water is threatened by nonpoint source pollution from agriculture and other sources and by aquifer depletion due to groundwater withdrawals in excess of groundwater recharge. In irrigated areas, groundwater levels may have to be controlled with drainage or pumped well systems to prevent waterlogging and salinization of soil. Salty drainage waters must then be handled in an ecologically responsible way. Water short countries can save water by importing most of their food and electric power from other countries with more water, so that in essence they also get the water that was necessary to produce these commodities and, hence, is virtually embedded in the commodities. This “virtual” water tends to be a lot cheaper for the receiving country than developing its own water resources. Local water can then be used for purposes with higher social, ecological, or economic returns or saved for the future. Climate changes in response to global warming caused by carbon dioxide emission are difficult to predict in space and time. Resulting uncertainties require flexible and integrated water management to handle water surpluses, water shortages, and weather extremes. Long-term storage behind dams and in aquifers may be required. Rising sea levels will present problems in coastal areas.     

Using HYDRUS-2D Simulation Model to Evaluate Wetted Soil Volume in Subsurface Drip Irrigation Systems

Drip irrigation is considered one of the most efficient irrigation systems. Alternatively to the traditional drip irrigation systems, laterals can be installed below the soil surface. Realizing the subsurface drip irrigation (SDI), which recently has been increasing in use as a consequence of advances in plastics technology, making SDI equipment more affordable and long lasting. Due to its potential high efficiency SDI may produce benefits, especially in places where water is a limited source. As the use of SDI is relatively new, a better understanding of the infiltration process around a buried point source can contribute to increased water use efficiency and consequently the success of drip irrigation system. In addition, proper design and management of such a system needs the judicious combination of drip spacing, discharge rates, irrigation duration and time interval between consecutive irrigations. To this aim, numerical models can represent a powerful tool to analyze the evolution of the wetting pattern during the distribution and redistribution processes, in order to explore SDI management strategies, to set up the duration of irrigation, and finally to optimize water use efficiency. In the paper the suitability of the HYDRUS-2D simulation model is verified, at the scale of a single emitter, on the basis of experimental observations, with the aim to assess the axis-symmetrical infiltration process consequent to subsurface drip irrigation. The model was then applied in order to evaluate the main dimensions of the wetted soil volume surrounding the emitter during irrigation as a function of time and initial soil water content. The investigation, carried out in a sandy-loam soil, showed the suitability of the model to well simulate infiltration processes around an emitter during irrigation. Model application allowed also, for the examined soil, to evaluate the emitter spacing accounting for the maximum soil depth to irrigate.     

Energy Variability and Produced Water: Two Challenges, One Synergistic Management Approach Using Pumped Hydroelectric Energy Storage

A number of compounding issues currently encourage a different management strategy of produced water from oil, gas, and coal bed methane. Environmental and economic constraints make it desirable to deploy water and energy resources efficiently and effectively to meet the demands of our populace while maintaining and supporting environmental resources. The following paper will outline one strategy to put some of the onshore produced water to beneficial uses. In this approach, the produced water is first cleaned and then used to supply water for pumped hydroelectric energy storage (PHS) to deploy electric energy on demand, and finally release that water back to the watershed or appropriate application. The primary purpose of this work is to suggest that produced water and PHS may complement each other. Additionally, it is suggested that revenue from energy storage can help provide for the cost of treatment of produced water. Once treated produced water could be put to additional uses with the potential to also bring in revenue.     

高炉冲渣水余热回收应用

高炉冲渣水作为一种低温废热源,具有温度稳定、流量大、热容量大的特点,充分回收利用高炉冲渣水余热可以为企业带来可观的经济效益,其环境效益和社会效益显著。     

中铝山西分公司供水系统的节能措施

本简要介绍了中铝山西分公司供水系统中采取的节能措施和取得的经济效益。     

攀成钢二烧余热回收工程

本文介绍了攀成钢二烧环冷机余热回收的工艺流程,简述了余热回收软水器、除氧器、蒸发器等主要设备特点及工作原理,对试生产中出现的除氧器喷水、软水硬度不达标等问题进行了分析并总结了处理方法,对余热回收经济效益和社会效益进行了概算。     

Multilevel Approach for Optimizing Land and Water Resources and Irrigation Deliveries for Tertiary Units in Large Irrigation Schemes. I: Method

This paper presents the area and water allocation model (AWAM), which incorporates deficit irrigation for optimizing the use of water for irrigation. This model was developed for surface irrigation schemes in semiarid regions under rotational water supply. It allocates the land area and water optimally to the different crops grown in different types of soils up to the tertiary level or allocation unit. The model has four phases. In the first phase, all the possible irrigation strategies are generated for each crop-soil-region combination. The second phase prepares the irrigation program for each strategy, taking into account the response of the crop to the water deficit. The third phase selects the optimal and efficient irrigation programs. In the fourth phase of the model, irrigation programs are modified by incorporating the conveyance and the distribution efficiencies. These irrigation programs are then used for allocating the land and water resources and preparing the water release schedule for the canal network.     

重油掺水乳化技术在镍精矿焙烧窑上的应用

文章介绍了重油掺水乳化燃烧技术在硫化镍精矿焙烧回转窑上的应用情况,认为该技术在焙烧窑上的应用是卓有成效的,在节能和环保方面具有显著的经济和社会效益。     

Knowledge-Based Model for Supplementary Irrigation Assessment in Agricultural Watersheds

In this paper a knowledge-based model for supplementary irrigation assessment in rainfed agricultural watersheds is presented. The supplementary irrigation assessment problem is divided into different components and is modeled separately. Geographic Information System (GIS) is used to aggregate spatially varying attributes required for the modeling. A graphical user interface is developed in a GIS platform by using the ERDAS macro language tools. The model was applied to two case study areas in India: a subwatershed of Gandheshwari area (West Bengal), and Harsul watershed (Maharashtra). In the Gandheshwari subwatershed, the water availability was found to be inadequate to meet the irrigation requirement and hence the model identified the areas that can be irrigated with different outsource water supply. On the other hand, surface runoff generated in the Harsul watershed was found to be sufficient to meet the supplementary irrigation requirement, thereby showing the feasibility for supplementary irrigation in the area. Using the model, the effect of any rainfall condition can be simulated and hence appropriate measures can be taken in advance to reduce the risk of crop failure.