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.     

Benefits of Flexible Irrigation Water Supply

This paper develops a general introduction into the concepts of a flexible irrigation water supply in rate, frequency, and duration together with the benefits to the farmer for doing so. A flexible water supply allows the farmer the opportunity to choose an on-farm irrigation practice that best meets the needs of the desired crop, the cost and availability of labor, and other local economic or social situations. As water quality issues are more closely tied to the issues of water quantity, water use efficiency must improve. A flexible irrigation water supply can lead to improved efficiencies. Non-point-source pollution and in-stream flows also become factors in other social issues such as the care of threatened and endangered species. Flexible supplies can again help. This paper also shows, through a case study, the application of a limited rate arranged system to an irrigation district in Washington State where significant flexibility has led to efficient water use and economic and environmental benefits.     

Wastewater Management in the 21st Century

A dialogue concerning potential future directions for the wastewater profession is initiated by identifying four principal challenges. The first is the perception by many (at least in the United States) that water pollution and water quality problems have largely been solved. Dramatic improvements during the 20th century (by the founders of our profession, not by us!) have eliminated many of the obvious public health and environmental issues associated with wastewater management. The second is population growth and the associated added stress on water resources. The third is the potential (at least perceived) conflict between providing improved water and wastewater service to the poor (especially in developing countries) and reducing the environmental impacts of our systems. The fourth is to determine whether we are wastewater managers, or more broadly water managers. These challenges can be addressed by adopting a broader, more holistic view of urban water management incorporating water supply, wastewater management, and storm water. A toolkit of existing and evolving technologies could be assembled and grouped into example systems. Improved methods for evaluating alternate urban water management systems based on sustainable development principles need to be developed. Achieving the vision of more sustainable urban water management systems requires that our professional organizations speak with one voice. Our profession must also reach out and engage a wide range of interests in defining and implementing dramatically improved solutions.     

Temporal and Spatial Variations in Bulk Chlorine Decay within a Water Supply System

Modern water treatment must maintain an acceptable balance between the microbial safety of potable water supply, the costs of treatment, and the formation of potentially harmful disinfection by-products (DBPs). In order to achieve the optimum balance, it is essential to understand and predict both the formation of DBP and the decay of chlorine, in relation to source water, treatment processes, storage, and supply. Reported herein are new data which demonstrate the lack of durability, precision, and accuracy associated with earlier empirical chlorine decay rate equations. This work develops an improved methodology for the prediction of variation in chlorine decay rates in distribution systems enabling practical, cost-effective prediction of the effects of both seasonal variations and management interventions on chlorine levels at treatment works and in distribution systems.     

Assessing Pressure Changes in an On-Demand Water Distribution System on Drip Irrigation Performance—Case Study in Italy

The hydrant pressure head in an on-demand water distribution system can be subject to high fluctuation depending on the discharge flowing inside the pipes, with consequent impacts on the performance of on-farm irrigation systems. In this work, an Italian water distribution system was analyzed using the AKLA model at upstream discharges of 1,200 and 600?L?s?1 to estimate the range of hydrant pressure variation. A computer model was developed, calibrated, and used to evaluate the performance of a drip irrigation system by relating the on-farm network with the hydrant characteristic curve at a certain operating status. The flow regulator within the hydrant played an important role in stabilizing the performance of the network at hydrant pressures higher than 27 m. At lower hydrant pressures, to apply the same amount of water, irrigation time must be extended by 17 and 95% for pressure heads of 20 and 12 m, respectively. These approaches described have great utility to ensure adequate irrigation management when water is delivered by pressurized on-demand systems.     

Measuring On-Farm Irrigation Efficiency with Chloride Tracing under Deficit Irrigation

Water is a limited resource in agricultural production in arid climates. Under such conditions, high irrigation efficiency can be obtained either through implementation of efficient irrigation systems such as drip or sprinkler systems or through the age-old practice of deficit irrigation with gravity systems. The method used to increase irrigation efficiency is often dictated by economic and/or social factors. In either case, the effectiveness of water management at the farm level needs to be evaluated by measuring irrigation efficiency. The objective of this study was to evaluate the irrigation efficiencies for three crops in Southern New Mexico using the chloride technique. The chloride technique is a simple method in which the natural chloride in the irrigation water is used as a tracer to estimate the leaching fraction and the irrigation efficiency at the farm level. Soil samples were collected from various fields in 15 cm increments to a depth of 180 cm at the end of the irrigation season. The samples were analyzed for moisture and chloride content. In addition to the chloride technique, on-farm irrigation efficiencies were measured using applied water, yield, and water production functions. Water production functions and yields were used to estimate total evapotranspiration while flow measurements were used to calculate the amount of applied water. The results showed that high irrigation efficiency can be accomplished using deficit irrigation. Irrigation efficiency values ranged from 83 to 98%. Irrigation efficiencies using the chloride technique were compared with efficiencies estimated from direct flow measurements. The differences between the two methods ranged from 2 to 11.4%. The results showed that even though the chloride technique is subject to sampling errors and simplified theoretical assumptions, it can be used to estimate on-farm irrigation efficiency with considerable accuracy.     

Impact of Irrigation Management Transfer on Land and Water Productivity and Water Supply in the Gediz Basin, Turkey

In the 1990s, Turkey started a fast transfer program in which a large proportion of government-managed irrigation systems were put into the hands of Water Users’ Associations (WUAs) in a very short space of time. One of the first systems to be handed over was the Gediz Basin. This study aims to set out the effects of the transfer of irrigation management in this basin on water and land productivity and water supply. For this purpose, the indicators of productivity and water supply proposed by the International Water Management Institute have been used to show changes between the pretransfer, transfer, and post-transfer periods. WUA averages for the post-transfer period calculated from the results ranged $2,076–$2,898?ha?1 for output per command area, $2,747–$4,585?ha?1 for output per irrigated area, $0.26–$0.68?m?3 for output per irrigation supply, $0.30–$0.63?m?3 for output per unit water consumed, 0.88–1.49 for relative water supply, and 0.99–1.99 for relative irrigation supply. During the period evaluated by the study, there was a decline in water supply indicators, as against a steady increase in the productivity of water and land use. The basic reason for this decrease in supply is the long-lasting and ongoing drought in the region.     

变频调速在工厂水系统中的节能应用

以济钢第一炼钢厂除尘加压泵组供水系统为例,介绍了变频调速恒压供水系统的结构及工作原理。变频调速恒压供水系统采用先进的控制技术与水泵机组相结合,具有高效节能、自动化程度高、操作灵活方便、供水压力稳定等特点。     

Making Asset Investment Decisions for Wastewater Systems That Include Sustainability

Effective integrated water management is a key component of the World Water Vision and the way in which aspirations for water equity may be realized. Part of the vision includes the promotion of sustainability of water systems and full accountability for their interaction with other urban systems. One major problem is that “sustainability” remains an elusive concept, although those involved with the provision of urban wastewater systems now recognize that decisions involving asset investment should use the “triple bottom line” approach to society, the economy, and the environment. The Sustainable Water Industry Asset Resource Decisions project has devised a flexible and adaptable framework of decision support processes that can be used to include the principles of sustainability more effectively. Decision mapping conducted at the outset of the project has shown that only a narrow range of criteria currently influence the outcome of asset investment decisions. This paper addresses the concepts of sustainability assessment and presents two case studies that illustrate how multicriteria decision support systems can enhance the assessment of the relative sustainability of a range of options when decisions are being made about wastewater asset investment.     

水泵的节能改造实践

在满足工艺要求不变的前提下,某公司整流循环水水泵经变频改造后节电率达到19.6%,经更换水泵及调换运行方式后,水泵节电率达到了61.3%,同时延长了水泵轴承、阀门的使用寿命,提高了供水系统的安全性和可靠性,达到节能降耗的目的。     

水泵变频调速节能改造的能效分析

针对合同制能源管理对供水系统改造产生的积极节能效果,以及改造方式影响水泵调速范围和节能效果的一些原因进行了分析,明确了供水系统变频调速改造应用的一些特点和注意事项。     

Predicting Soil Salinity under Various Strategies in Irrigation Systems

This paper presents a model to estimate the soil salinity for different on-farm management strategies under irrigated conditions. It is based on research in the Mani?oba irrigation scheme in northeast Brazil, where upward flow from the shallow water table is the main cause of soil salinization. The model calculates soil water and salt balances for the topsoil. It is calibrated for the topsoil of abandoned plots and for the root zone (0.9?m) of mango trees. Simulating the effect of different management scenarios on soil salinity may help to organize the switch from intensive surface irrigation to more efficient irrigation practices.     

A coverage plan for health centres in Murewa district in Zimbabwe: an example of action research

Good access to health facilities providing good first-level health care remains problematic in many developing countries. It is a hindrance to effective and efficient functioning of the hospital, as outpatient departments become overcrowded with patients from areas without health centres. In many cases the quality of care delivered to these patients is poor because within the district health system the hospital is not the best place for the supply of comprehensive, integrated and continuous care. Eventually, high hospital involvement in first-level care can jeopardize the delivery of adequate referral care for those patients who desperately need the hospital's technology and expertise. This paper provides an account of the way this problem was investigated and managed by the district health management team in the Murewa district in north-east Zimbabwe. The design of a comprehensive 'master plan' or 'coverage plan' is presented as well as the problems and difficulties encountered. The Murewa experience highlights the relevance of a coverage plan for rational and coherent health infrastructure planning at district level. The approach followed by the Murewa team illustrates the use of action research as an integral part of the management of district health systems.     

浅谈建筑给排水工程的质量控制

随着我国工程建设项目管理体制改革的不断深化,建筑工程质量有了显著提高,同时也给施工单位提出了更高的要求。因此,为了提高给排水工程的施工质量,本文从工程施工前期准备、工程施工过程中、工程施工后期三个阶段,结合实际案例说明建筑给水排水工程的质量控制要点以及预防措施,以期工程施工单位更加深入、细致地做好各项项目管理工作。     

采用一体化设备处理酸性矿井废水

一体化处理设备不仅适用于矿井废水而且可用于给水处理,具有工艺组合灵活。控制方便,占地面积小,维护工作量少等优点。与之配套的自动控制设备不仅能够优化工艺运行参数,而且还配有远程监控功能。方便运行与管理。     

Parasites, animal production and sustainable development

Ecologically sustainable development is aimed at reducing environmental degradation while enabling economic development with equity between the developed and developing worlds and between generations. Parasite control in livestock can both contribute to, and take advantage of, sustainable agriculture. This will tend towards less intensive, lower input, diversified crop and animal production with less risk of parasite-induced losses and greater opportunities for integrated control including the exploitation of grazing management. Chemotherapy will continue to play a part but the most serious problem is resistance in the target species. Except for a few isolated issues, currently used parasiticides are relatively minor contaminants of the food supply or the environment. Nevertheless, the compounds of the future will need to be narrow-spectrum, non-persistent and rapidly degraded, with convenience in the hands of the user reduced in importance. Environmentally friendly alternatives to chemotherapy, including genetic resistance of hosts, vaccines, and biological control, show considerable promise and must be pursued. Sustainable systems pose optimisation problems and more attention must be given to systems research, models and products to aid decisions. If governments are serious about sustainable development, greater support will be needed for longer-term patient, multi-disciplinary research.     

基于SCM的企业信息系统框架结构研究

从现代企业供应链管理（SCM）的需求出发，结合某合资公司的信息系统设计方案，分析了用于企业供应链管理计算机信息系统的框架结构以及功能设置。建立了一套与之相适应的能准确及时获取外部企业相关数据的新型管理信息系统。本系统采用外托数据管理中心的模式，解决了供应链中的各个企业信息共享的问题，使得供应链具有更大的柔性。因此，采用外托数据管理中心的方式集成的供应链管理系统，是企业实施供应链管理的较优系统集成结构。     

Forecasting Domestic Water Use in Rapidly Urbanizing Areas in Asia

This paper summarizes some of the recent trends in domestic water use in both developed and developing countries, so as to better identify the principal factors influencing the demand. The focus is on the adoption of a more microapproach to demand forecasting, rather than the traditional use of overall averages, so as to move towards more cost effective and resource efficient supply schemes. An important aim of the paper is to alert designers of new water supply schemes in developing countries to the need to apply caution to the belief that per capita water use will continue to increase in tandem with the general economic development of the area being served, to the extent that it reaches the levels experienced in more developed countries. Survey data are presented from a range of locations to illustrate the trends in domestic water use for both connected households and community standpipes.     

Alternative Delivery Scheduling for Improved Canal System Performance

Alternative delivery scheduling approaches intended to overcome the problem of low efficiency in Indian irrigation projects are presented. The features of the historical delivery schedules in the Right Bank Main Canal system of Kangsabati irrigation project, located in the state of West Bengal, India, have been studied, and nine modified schedules of varied rate rotation (variable discharge, constant duration, and constant frequency) prepared. Daily water balance simulation of the command area in the Kharif (rainy) season has been used to compare the performance of alternate schedules. An alternate schedule with three irrigations of 20 to 21 days’ duration, followed by 20 days of canal closure after each irrigation, was found to perform the best. The proposed alternate schedule results in a better match between supply and demand and results in 13% water saving when compared to the existing schedules. The irrigation periods of this schedule cover the expected dry spells and critical rice growth stage. An added advantage of the proposed schedule is an improvement in the reliability of supply, which will encourage farmers to invest more on other inputs resulting in enhanced water use efficiency and improved yields.     

OCCASION: New Planning Tool for Optimal Climate Change Adaption Strategies in Irrigation

To sustain productive irrigated agriculture with limited water resources requires a high water use efficiency. This can be achieved by the precise scheduling of deficit irrigation systems taking into account the crops’ response to water stress at different stages of plant growth. Particularly in the light of climate change with rising population numbers and increasing water scarcity, an optimal solution for this task is of paramount importance. We solve the corresponding complex multidimensional and nonlinear optimization problem, i.e., finding the ideal schedule for maximum crop yield with a given water volume by a well tailored approach which offers straightforward application facilities. A global optimization technique allows, together with physically based modeling, for the risk assessment in yield reduction considering different sources of uncertainty (e.g., climate, soil conditions, and management). A new stochastic framework for decision support is developed which aims at optimal climate change adaption strategies in irrigation. It consists of: (1) a weather generator for simulating regional impacts of climate change; (2) a tailor-made evolutionary optimization algorithm for optimal irrigation scheduling with limited water supply; and (3) mechanistic models for rigorously simulating water transport and crop growth. The result, namely, stochastic crop-water production functions, allows to assess the impact of climate variability on potential yield and thus provides a valuable tool for estimating minimum water demands for irrigation in water resources planning and management, assisting furthermore in generating maps of yield uncertainty for specific crops and specific agricultural areas. The tool is successfully applied at an experimental site in southern France. The impacts of predicted climate variability on maize are discussed.