震后特殊供水状态下的供水管网水力分析

供水管网的抗震性能,是指供水管网在地震作用下能够满足震后城市特定用水需要(需水量和水压)的能力.在地震作用下,供水管网中的埋地管线破坏位置多隐蔽、分散,加上震后救灾力量的局限和救灾活动的迟滞,难以迅速发现并隔离受轻微和中等震害的管线.另一方面,为了控制震后次生火灾的蔓延,又必须保证主干供水管网持续供水.在震后维修期间,供水管网处于特殊的供水状态--带渗漏供水状态.为了评价城市供水管网的抗震能力,需要进行震后特殊供水状态下供水管网的水力分析.给出了震后带渗漏供水管网的水力分析模型和程序结构,同时以上海市浦东新区供水管网为例,演示了震后供水管网水力分析的应用方法.     

变频器在恒压供水系统中的应用

介绍采用自带PID(比例积分微分控制器)功能的变频器恒压供水系统的工作原理、控制系统设计及功能。     

对西部欠发达地区环保投入机制的思考

以长江上游地区为例，分析了西部欠发达地区环保投入机制存在的问题及原因，认为西部欠发达地区构建环保投入机制的基本思路是：畅通现有的环保投入渠道，开辟新的环保投入渠道，增加环保投入的供给；加强对环保投入资金、环保项目及工程的管理，提高环保投入资金的使用效果，压缩环保投入的需求。     

Universal access to water and sanitation: Why the private sector must participate

Against the background of the current state of provision of drinking water and sanitation in the world — with one billion lacking safe water, and 2.2 billion not having adequate sanitation — this article argues that private participation is necessary. The most important issues for the management of water utilities in the 21^st century are identified as mobilizing investment for the highly capital intensive operation of water supply and sanitation infrastructure, and achieving efficiency in the delivery of services. The article highlights the issues that need to be raised if private investment is to be seriously considered as an alternative. Case studies, especially from Latin America (Argentina, Chile, Peru, Bolivia), illustrate different modes of private participation, and possible reasons for successes and failures are discussed. The article stresses that regardless of the modality of private sector involvement, on‐going government regulatory responsibility in the water sector is crucial. It suggests that regulatory policy must go beyond just setting tariffs, to develop standards for drinking water quality and waste treatment, as well as other standards. In conclusion, the article recognizes that numerous and increasingly difficult challenges face utilities in fulfilling their responsibility to deliver drinking water of adequate quality, in sufficient quantity, and at affordable prices, as well as safe and sustainable disposal of wastewaters for members of urban and rural communities.     

EVALUATION OF PRACTICES IN WATER SUPPLY FORECASTING1

ABSTRACT: Snowmelt runoff is a primary source of water supply in much of the Western United States. Multipurpose planning requires long-range forecasts and the accuracy of the forecasts has a significant effect on economic benefits. In an effort to increase the accuracy of snowrnelt runoff forecasts, selected practices in water supply forecasting were evaluated. These practices include 1) using multiple regression in developing forecasting models;2) using a model that was calibrated to make forecasts an April 1 for making forecasts at other times;3) using maximum snow water equivalent measurements in forecast equations; and 4) using weighted snow water equivalent measurements for making forecasts. The results of a case study indicate that forecasting accuracy is significantly affected by these practices. Goodness-of-fit statistics may not be indicative of the accuracy of forecasts when the prediction equations are used to make forecasts for dates other than that used in calibration. The use of maximum snow water equivalentmeasurements and weighted averages did not improve forecast accuracy.     

ECONOMICS OF CONTROLLING NATURAL SALT SOURCES IN THE ARKANSAS RIVER BASIN1

ABSTRACT: The methodology underlying, and the estimates incorporated in the Corps of Engineers' economic evaluation of the Arkansas River Basin Chloride Control Project are evaluated and judged deficient in several ways. An improperly specified alternative cost analysis probably results in overestimates of the total regional demand for water, the demand for Arkansas River Water, and the cost-savings realized with the project in place. The quantitative effect of these errors is not determined. However, other adjustments are identified which are evaluated using the Corps' data. These adjustments reduce B/C from 2.64 to 0.57; principally as a result of corrections for over-estimates of cost-savings in steam-electric generation, and for use of improper discounting procedures and gross output-earnings ratios.     

INTEGRATED PLANNING OF RURAL WATER SUPPLY AND SANITATION1

ABSTRACT: Development schemes to improve the health of the rural populace through prevention of the transmission of communicable diseases should be considered in the context of some kind of “Sanitation Package” to ensure effectiveness. The general practice of concentrating resources on limited objectives, like water quality improvement, is shown to be less effective than allocating the same resources to multi-objectives defined in the Sanitation package. Systems Dynamic Modeling based on the DYNAMO II language, is presented as a capable tool for sanitation systems planning.     

WATER SUPPLY DILEMMAS OF GEOTHERMAL DEVELOPMENT IN THE IMPERIAL VALLEY OF CALIFORNIA1

Abstract: There are four known geothermal resource areas in the Imperial Valley that have a combined potential of over 4,000 megawatts of electrical energy for 25 years. Water resources available to support geothermal enerfy development are imprted Colorado River water, agricultural waste waters, Salton Sea water, and groundwater. In addtion, geothermal power plants can produce their own cooling water from steam condensate. Nevertheless, the relatively high water requirements of geothermal facilities along with a series of real and potential constraints may cause water supply dilemmas involving both the acquistion and use of cooling water. Important constraints are institutional policies, water supply costs, technical problems, and impacts upon the Salton Sea. These constranits and related dilemmas are examined in light of relevanty information on the valley's water resources, geothermal resources and energy technologies, cooling water requrements, and water supply options.     

IMPLEMENTATION OF AN OPTIMIZATION MODEL FOR OPERATION OF A METROPOLITAN RESERVOIR SYSTEM1

ABSTRACT: A deterministic dynamic programming optimization model with a refining sectioning search procedure is developed and implemented to find least cost withdrawal and release patterns for water supple from a multiple reservoir system serving a metropolitan area. Applications are made to teh four reservoir system operated by the city of Dallas, Texas. A realistic cost structure, including nonlinear power consumption, block rate unit power costs, and flow dependent power consumption for intracity water distribution, is utilized. Applications are made to find least cost operating patterns and, as well, by inclusion of a water loss penalty function, supply patterns which will reduce evaporation water losses for the Dallas system.     

WATER SUPPLY AS A LIMITING FACTOR IN DEVELOPING COMMUNITIES: ENDOGENOUS VS. EXOGENOUS SOURCES1

ABSTRACT: A growing number of developing communities in New Jersey is planning for an ultimate population that would be supplied by endogenous sources of water. At the state and national level, however, reliance on exogenous sources appears to be in favor. Both viewpoints, of course, recognize that water supply is one of the major critical factors in determining the capacity of a land area to support population. Three planning issues that bear on this endogenous-exogenous source controversy are discussed: 1) deep aquifers which have recharge areas in other political jurisdictions and are therefore regulated by other bodies will not count as an endogenous source, reliance will be placed only on shallow water table aquifers which are recharged by local precipitation; 2) total development of the groundwater resources of a headwaters community could result in severe base flow diminishment, thereby supporting the notion that these communities have a regional responsibility to restrict their growth so as to preserve and protect the water supply for downstream users; and 3) yield decrementing estimates, i.e., how much recharge water is lost to runoff as a consequence of development, are needed in order to assess the magnitude of local water resources.