Households＇ Assessment of the Water Quality and Services of Multi-model Urban Water Supply System in the Informal Settlements of Dar es Salaam, Tanzania

In the global south wide range of studies highlight the limitations of the single-modelled public urban water system to meeting the endogenous water preferences of the urban population. Studies also touched on the complementary roles of private water actors to the single-modelled public water supply system in the urban water supply network. Multiple of urban water supply systems （multi-model） co-exist in the urban landscape of global south. However, it is unclear and largely inconclusive on the suitable and satisfactory urban water supply model that meets the water consumption needs of informal settlement dwellers in the global south. This study draws the experiences of households in the informal settlements using a case-study with cross-sectional survey strategy to assess the suitability of the multi-model urban water supply system for sustainable urban water supply in the informal settlements. A total of 292 households were randomly sampled alongside 35 purposively sampled private water actors and public water departments. The data were collected through face to face interviews. Findings show that water supply services of the multi-model water supply system are inevitably suitable for the water consumption needs of informal settlements’s dwellers. The operation of the multi-model water supply system is flexible and able to accommodate the diverse water consumption preferences and choices of the different socio-economic groups in the informal settlements. We observed that multiplicity of urban water supply system increases households’ access to water but does not necessarily improve the quality of water serve in the informal settlements. The paper recommended for the formalisation and adoption of the multi-model urban water supply system to meet the growing demand for improved water supply and services in the informal settlements.

Research on Leak Location Method of Water Supply Pipeline Based on MVMD

At present,the leakage rate of the water distribution network in China is still high,and the waste of water resources caused by water distribution network leakage is quite serious every year.Therefore,the location of pipeline leakage is of great significance for saving water resources and reducing economic losses.Acoustic emission technology is the most widely used pipeline leak location technology.The traditional non-stationary random signal de-noising method mainly relies on the estimation of noise parameters,ignoring periodic noise and components unrelated to pipeline leakage.Aiming at the above problems,this paper proposes a leak location method for water supply pipelines based on a multivariate variational mode decomposition algorithm.This method combines the two parameters of the energy loss coefficient and the correlation coefficient between adjacent modes,and adaptively determines the decomposition mode number K according to the characteristics of the signal itself.According to the correlation coefficient,the effective component is selected to reconstruct the signal and the cross-correlation time delay is estimated to determine the location of the pipeline leakage point.The experimental results show that this method has higher accuracy than the cross-correlation method based on VMD and the cross-correlation method based on EMD,and the average relative positioning error is less than 2.2%.

Urban Water Supply Industry Marketization of China in View of Public Water Service and Water Resource Management

Started with the discussions on the value orientation of urban water supply industry marketization,the article points out that the current urban water supply industry marketization reform is inconsistent with the goal of public water service equalization to some extent.The article also analyzes the problems emerged in urban water supply industry marketization reform and various rea-sons in view of efficiency and fairness.An efficiency and fairness oriented management model is built in this article to illustrate how the government should conciliate interests of various communities involved in the process of marketization reform of the urban water supply industry so as to actualize the coordination of efficiency and fairness.At the end,an assumption on urban water price is put forward to help achieve the public water service equalization.

Characteristics of groundwater and urban emergency water sources optimazation in Luoyang,China

The construction of emergency water sources is the material basis for ensuring urban water safety,and it is also an inherent requirement for maintaining social stability and development.The hydrogeological characteristics of groundwater in Luoyang City from the aspects of the division of groundwater aquifer groups,water yield property and groundwater dynamics were described in this paper.Two emergency water sources were selected on basis of comprehensively considering groundwater resources and ecological environmental effects,groundwater quality and exploitation technology,etc.Then it further analysed the aquifer types,water yield properties and groundwater recharge,runoff and discharge conditions of the two emergency water sources,and evaluate the groundwater resources quantity of the water sources.The results are that the shallow underground aquifer in Luoyang City is thick,coarse,and stable in lithology and thickness.The two water sources enjoy good exploitation potential and can be used as backup water sources to supply water in the event of a water source crisis.

Potential contributions to Beijing's water supply from reuse of storm-and greywater

In order to find new approaches to alleviating the water crisis in Beijing which is caused by among others dwindling precipitation and rapid growth of population and manifests in a rapidly declining groundwater table this study explores decentralized stormwater harvesting and greywater reuse at household level as a means to reduce groundwater abstraction and water transfer from other regions.Based on a desktop case study two concepts for combined harvesting and reusing of storm-and greywater are presented.With rough pre-assumptions calculations show that a saving of 67.8%of tap water consumption can be achieved with the upgrading concept compared with 5.9% with the simple downgrading concept.The saving with the upgrading concept equals 0.545 ×109 m3 annual water volume if 20 million Beijing people apply this approach.Despite numerous prerequisites such as water treatment technology space demand energy and cost and public acceptance this paper advocates combining stormwater harvesting and greywater reuse in households with other measures for Beijing’s sustainable water management.

Groundwater Quality Assessment for an Indian Urban Habitat： A GIS Approach

Groundwater is an essential source of drinking water for many Indian urban habitats. Large numbers of people consume ground water instead of municipal tap water due to contamination of tap water. Groundwater is extracted from thousands of bore wells, and used for potable purpose without proper testing and treatment. This paper describes a groundwater quality monitoring strategy and database model developed for Gulbarga city, located in Karnataka, India. Sampling wells are selected one each in 55 wards of the city corporation having easy access for regular sampling. Various attributes of sampling wells including their spatial coordinates, location address and a photograph are registered for ready recognition on site. Water samples are collected and analyzed for various physico-chemical parameters. Spatial coordinates and levels of sampling points are measured on site using a hand held GPS instrument. Gulbarga city map is digitized. A GIS database of the measured spatial and water quality data is developed using ArcGIS Desktop 9.3, and ground water quality maps are prepared which may serve as useful tools for developing policy, and regulatory mechanism for sustainable groundwater use.

坚持“四水四定”推动经济社会高质量发展——以宁夏回族自治区“四水四定”创新实践为例

坚持“四水四定”,强化水资源刚性约束,既是缓解我国水资源供需矛盾、保障水安全的必然选择,也是推动高质量发展、建设美丽中国的客观要求。文章以宁夏回族自治区为例,深入分析了宁夏回族自治区“四水四定”改革实践,总结了相关经验启示,为探索以水资源节约集约利用推动经济社会高质量发展提供了参考。

新时期阿克苏地区城乡供水安全保障体系探析

本文以阿克苏地区城乡供水安全保障体系为例,在对当地城乡供水现状及存在的问题进行分析的基础上,结合未来发展和新时期供水思路,因地制宜,积极推进城市群供水、城乡一体化供水和集中供水,实施多水源供水和应急备用水源工程,构建与当地经济社会发展相适应的城乡供水安全保障体系,大大提高了供水保障程度。研究成果可为其他地区城乡供水提供一定的参考和借鉴。

京津冀平原非常规水资源利用前景分析及其生态环境效应

[研究目的]京津冀平原水资源严重短缺,供需矛盾十分突出,加大非常规水资源利用力度,形成多元供水格局,可有效缓解水资源供需矛盾,对支撑京津冀协同发展区社会经济协调发展和推动生态文明建设具有重要意义。[研究方法]文章系统开展非常规水资源供水方向、开发利用模式和供水规模分类数据统计,依据各省(直辖市)非常规水资源供水规划及配置目标,分析其开发利用前景及其生态环境效应。[研究结果]该区非常规水资源主要包括微咸水、再生水、淡化海水、雨洪水,其中微咸水主要分布于中东部平原的天津、沧州、衡水等地,供水前景为5.43×10^(8)m^(3);再生水利用以北京、天津等大中型及工业城市为主,供水前景为34.22×10^(8)m^(3);淡化海水利用以天津等滨海城市为主,供水前景为4.19×10^(8)m^(3);雨洪水利用较分散。[结论](1)微咸水用于农业灌溉存在土壤盐渍化风险,需加强水盐调控。(2)再生水用于河流生态补水,沿线地表水富营养化,地下水体未受到明显污染;地下水浅埋区开展再生水灌溉,会增加硝酸盐污染风险;建议将高风险的新兴污染物纳入再生水利用监控体系。(3)海水淡化尾液浓盐水、冷却热水可能改变天然海洋生态系统的分布、构成与多样性,应予以关注。(4)雨洪水利用可降低污水入河的水质风险,但过度利用可能影响区域生态系统的稳定性,建议城市区适度扩大利用。

供水工程新近系红层区斜坡深层变形破坏模式分析

针对新近系红层区斜坡变形破坏模式认识不足的问题,通过对以往工程区斜坡破坏现象的调查分析,寻找已有深层破坏形成的滑坡体,反分析滑坡体破坏前原始斜坡地质结构模型,并建立典型斜坡深层破坏模式,根据变形体主要工程地质条件,建立红层斜坡变形体的三维数值模型,分析其在天然、地震及降雨等条件下的稳定性。结果表明,通过建立的新近系地层不同岩段区斜坡深层破坏模式,识别出新近系地层区供水工程20#支线沿线有一个大型深层破坏斜坡变形体。该斜坡变形体在降雨条件下的稳定性较差。

供水工程民和组地层区斜坡深层变形破坏模式分析

目的红层软岩斜坡深层变形破坏具有一定隐蔽性,为解决寻找和识别具有一定隐蔽性的民和组地层区斜坡深层变形破坏变形体的问题。方法结合引黄济宁供水工程,依据民和组地层区斜坡变形破坏现象的调查分析,寻找已有深层破坏形成的滑坡体,反分析滑坡体破坏前原始斜坡模型,模拟分析原始斜坡滑动破坏触发因素,建立民和组地层区典型斜坡深层变形破坏模式;然后根据建立的斜坡深层变形破坏模式,寻找识别民和组地层区深层变形破坏斜坡变形体,对典型斜坡变形体构建三维数值模拟模型,分析天然、地震及降雨等条件下的斜坡变形体的稳定性。结果通过研究,建立了民和组地层区不同岩段典型斜坡深层变形破坏模式,识别出民和组地层区供水工程22#支线沿线有一个大型深层变形破坏斜坡变形体,在暴雨条件下会沿砾岩层与泥岩夹层交接面发生深层滑动破坏。结论通过建立典型斜坡深层变形破坏模式识别深层变形破坏斜坡变形体并分析其工程稳定性,可以减少意外发生斜坡深层变形破坏现象,研究成果可为工程施工图设计提供依据,也为民和组地层区地质灾害分析提供参考。

韧性城市建筑“平急结合”设计给排水应对关键措施探索

简介韧性城市建筑中适用于临时隔离收治点的建筑类型,提出建立临时隔离收治点“平急结合”设计的标准体系构想,解析作为临时隔离收治点的新建建筑、既有建筑在设计或改造中的给排水应对措施,重点就条件预留、用水定额、系统定型、管道布设、设备选用、污水处理等方面进行深入探索。

对某城乡供水工程自动化控制的设计和应用研究

城乡供水自动化是解决农村饮水安全的重要措施,能够有效保证供水工程的管理决策能力和应用服务水平。总结了某城乡供水项目中自动化控制的设计和应用,不仅能有效的弥补水利工程建设过程中存在的不足,此外在实现水利工程长远发展、提高水利工程管理水平中也发挥了重要性作用,可以实现城乡供水后期运行中节水、减员、降本、增效的功能优势,推动了城乡供水的均等化服务,有效巩固当地的脱贫攻坚工作。

我国城市供排水在线监测技术发展与标准化历程

随着我国供排水设施规模快速增长、各类新兴业务的大量涌现以及在线监测技术的不断进步,供排水在线监测技术得到了快速发展和应用。为解决业务需求和技术标准化需求,研究者对在线监测设备的性能与运行维护要求、监测系统布局优化方案等方面开展了一系列研究。随着在线监测技术的逐渐成熟,该技术在供水全流程监控、排水设施运行监控与问题诊断、海绵城市建设效果评价、水环境治理中的排污溯源等方面得到了广泛应用。同时,为规范供排水在线监测技术的应用,我国供排水在线监测技术标准经历了从无到有并逐步完善的过程,建立了以行业标准为主、以地方标准和团体标准作为补充的标准体系。

基于等效场景的供水管网抗震可靠性评估

供水管网抗震可靠性是满足用户在可能地震作用下用水需求的能力。目前,多数供水管网抗震可靠性评估采用蒙特卡洛模拟产生大量的震损样本进行评估。然而,此方法在评估大型、复杂管网时,将带来极大的工作量和超高的时间成本。为了克服这些问题,提出等效场景方法以提高计算效率。首先,利用震损场景生成后验概率;然后,利用后验概率生成等效场景;最后,通过等效场景确定节点可靠性指数和系统可靠性指数。将文中所提算法与传统蒙特卡洛方法的模拟结果进行对比。研究结果表明:基于后验概率生成等效场景方法是可行的;地震烈度8度时采用100个等效场景评估其可靠性,存在少数评估误差超过10%的节点,其余小地震烈度评估误差均小于5%。将100个等效场景提高至250个,可将评估误差控制在5%以内。因此,该文提出的算法可以在保证结果准确的同时提高计算效率。

基于聚类分析法的江苏省城乡统筹供水规划模式研究

在充分调查江苏省城乡统筹区域供水情况的基础上,分析每个供水片区水源地布局及取水规模、水厂布局及供水规模、人口密度、经济社会发展水平等特征;采用聚类分析法,以单个水源地服务面积、单个水源地服务人口和单个水源地取水规模为主要分类指标,综合考虑每个供水片区水厂数量、供水服务面积等因素,将江苏省供水规划模式分为适度集中、中度集中及高度集中供水规划模式,分析不同供水规划模式特征及适用范围;采用FISH判别分析方法,构建区域供水规划模式判别函数,为规划模式的选择提供数学函数。

湖北省“高品质”饮用水现状分析及发展对策

“十四五”规划提出“推动绿色发展,促进人与自然和谐共生,改善人民生活品质,提高社会建设水平”。对湖北省城市居民饮水现状进行调研发现,地区发展对居民饮水水源的选择有影响,家庭收入越高越倾向饮用包装水与使用家用净水器,年龄层次较年轻的调研对象更倾向饮用包装水,饮用方式更倾向于直接饮用。根据对湖北省内的“全面提质”高品质饮用水项目和48个“部分提质”高品质饮用水项目现状进行调查,发现目前湖北“高品质”饮用水项目存在投资资金压力大、水质标准支撑不足、技术路线繁杂、监管责任不明确等问题。综合湖北省内24家水司、67名行业专家及管道直饮水企业等行业调研意见,为湖北省“高品质”饮用水发展提出对策与建议。

城市轨道交通车站空调冷冻水系统定温差变供水温度和大温差控制策略转换条件研究

[目的]为实现城市轨道交通车站空调冷冻水系统在定温差变供水温度和大温差两种工况下的整体能耗最低,需对这两种控制策略的转换条件进行研究。[方法]以郑州某城市轨道交通车站为例,基于TRNSYS(瞬时系统模拟程序)建立定温差变供水温度和大温差两种工况下的空调冷冻水系统模型,在满足空调冷冻水系统末端制冷量需求的前提下,分别研究冷冻水温差不变、供水温度为7~12℃,以及供水温度不变、供回水温差为5~10℃时对空调冷冻水系统能耗的影响。[结果及结论]两种控制策略的转换条件为:负荷率小于等于40%时,使用定温差变供水温度控制策略更节能;负荷率大于50%时,更适合采用大温差控制策略。该转换条件不仅能满足车站人员舒适度的要求,还实现了两种控制策略联合调控的目标,最终达到降低空调冷冻水系统整体能耗的目的。

大直径城市供水管道水锤作用监测与计算方法研究

随着我国城市建设的发展,长距离供水管道应用众多,而在长距离供水管道设计过程中水锤作用不可忽视。使用高频动态压力传感器进行现场监测试验,对比传统水锤方程组和“FSI四方程模型”水锤计算的结果,并同时基于ABAQUS数值模拟软件开展相关数值模拟,对大直径供水管突然关机时产生的水锤作用进行研究。结果表明:在水锤作用下压应力最大部位位于管顶、管底内侧,拉应力最大部位位于管腰内侧;壁厚与应力和位移呈正相关,管径与应力呈正相关且与位移呈负相关,而管道埋深对其应力和位移的影响很小。研究的计算结果与数值模拟结果接近监测真实值,对水锤模拟有一定指导意义。

城市轨道交通贯通供电方式牵引网分段供电方案及故障辨识方法

[目的]城市轨道交通线路采用贯通供电方式时,因牵引网结构复杂且无备用,牵引网发生故障时可能会扩大停电范围,为此需要对牵引网的分段供电方案进行优化。[方法]提出了一种适用于贯通供电方式的牵引网分段供电方案。基于牵引网分段供电拓扑特征,结合车-网耦合特性,提出了分段故障、过渡段故障的辨识方法。对牵引网分段短路和过渡区短路2个故障场景的控制方案进行了分析,描述了这2个故障场景下牵引网的自愈流程,并制定了这2个故障场景对应的断路器控制方案。以广州地铁18号线牵引供电系统为例,通过MATLAB/Simulink软件仿真,验证了所提分段供电方案及故障辨识方法的正确性和可靠性。[结果及结论]该方法可有效辨识故障区段。牵引网故障断路器控制方案可为分段和过渡区提供可靠的主保护,可保证广州地铁18号线牵引供电系统稳定、高效运行。