Modeling of Drinking Water Distribution Networks Using Stochastic Demand

Residential water demand is one of the most difficult parameters to determine when modeling drinking water distribution networks. It has been proven to be a stochastic process that can be characterized as a series of rectangular pulses with a set intensity, duration and frequency. These parameters can be determined using stochastic models such as the Neyman-Scott Rectangular Pulse (NSRP) model. The NSRP model is based on the solution of a non-linear optimization problem. This solution involves theoretical moments that represent the synthetic demand series (equiprobable) and the observed moments (field measurements) that statistically establish the measured demand series. The NSRP model has been applied for residential demand, and the results have been published. However, this model has not been validated for a real distribution network or compared with traditional methods. The present study compared the results of synthetic stochastic demand series, which were calculated using the NSRP model, applied to the determination of pressures, flow rates and leaks; to the results obtained using traditional simulation methods, which use the curve of hourly variation in demand, and to actual pressure and flow rate measurements. The Humaya sector of Culiacan, Sinaloa, Mexico, was used as the study area.     

Classification of Drinking Water Quality Index and Identification of Significant Factors

Water pipes are considered to be one of responsible sources for the water pollution. Among these sources of water supply, the water pipes are the only source of carrying out fresh or processed water into lakes, ponds and streams etc. In Pakistan, knowledge on the condition of water pipes is scarce as deterioration of water pipes are hardly inspected due to high cost. The aim of the current research was to examine the quality of water pipelines of eight districts of South-Punjab, namely, Mianwali, Khushab, Layyah, Bhakkar, Dera Ghazi Khan, Muzaffargarh, Rajanpur and Rahim Yar Khan. Selected sampling stations were analyzed for physio-chemical parameters such as pH, Total Dissolve Solids (TDS), Sulfate (SO₄), Chlorine (Cl), Calcium (Ca), Magnesium (Mg), Hardness, Nitrate (NO₃), Fluoride (F) and Iron (Fe). The data pertaining water monitoring contain different parameters and seem difficult work for the interpretation of water quality by managing different parameters separately. For this purpose, National Sanitation Foundation Water Quality Index (NSF-WQI) was determined to communicate the quality of water in a simple form. Besides this, groups comprising of similar sampling sites based on water quality characteristics were identified using unsupervised technique. Factor Analysis (FA) has been performed for extracting the latent pollution sources that may cause the more variance in large and complex data. The calculated values of WQI from 1600 sampling stations ranging from 20.73 to 223.74 are divided into five groups; Excellent to Unsuitable class of waters with the average value 62.09 described as good limit for drinking water. Further sampling stations are divided into five optimal clusters selected with suitable k value obtained from Silhouette coefficient. Results of k-means clustering are also verified with natural groups made by WQI. Analysis of multivariate techniques showed several factors to be responsible for the water quality deterioration. It is found out from the FA that three latent factors such as organic pollution, agriculture run-off and urban land use caused 83.30 % of the total variation. Hence, water quality management and control of these latent factors are strongly recommended.     

地下饮用水水源地安全保障评价体系构建

分析阐述了饮用水水源地安全评价现状,在概括水源地安全内涵的基础上,从水质、水量、脆弱性、应急能力4个方面构建了地下饮用水水源地安全保障评价指标体系,并给出了指标选择的原则和必要性。所构建的安全保障评价指标体系可为水源地的安全保障、规划工作提供科学依据,具有实际应用价值。     

ARIMA-SVR组合方法在水质预测中的应用

针对复杂水域水质变化机理难以掌握、水质预测建模困难且预测精度低的问题,将时间序列分析方法与机器学习方法引入水质预测领域,提出了基于差分自回归移动平均(ARIMA)与支持向量回归(SVR)组合模型的水质预测方法。数据经过预处理后先由ARIMA模型对其进行线性拟合,然后通过SVR模型预测残差以补偿其中的非线性变化。选择巢湖水域2004—2015年间的pH和溶解氧监测数据作为试验样本,通过Hodrick-Prescott(HP)滤波方法分析,结果表明2组数据具有不同的趋势特性和波动特性。根据精度评价指标对比分析模型的预测效果,结果表明组合模型预测精度显著提高,pH和溶解氧预测值与观测值间的相关系数均达到了0.99,均方根误差分别为0.20和0.61,平均绝对百分比误差分别为2.2%和6.6%。本研究所建立的组合预测方法具有较高的预测精度和较强的泛化能力,适用于复杂水域的水质预测。     

基于时间序列预测法的水利发展指标体系研究

基于时间序列分析法,采用指数曲线、修正指数曲线、对数曲线和乘幂曲线分析方法进行组合比选,根据各项指标的特点,结合国家、省级及区域宏观调控的影响以及变化趋势等因素,对甘肃水利发展规划目标指标体系6大类26项指标进行了近期2015年和远期2025年的预测研究。结果表明:采用定量分析方法,可以预测甘肃省水利发展近、远期目标与任务动态区间,为甘肃省"十二五"水利发展规划提供重要参考。     

基于EFDC模型的明湖水库水质数值模拟及预测

基于EFDC模型,以支鱼港补水闸和大尖退水闸实测流量、水质、水位为计算边界,模拟并探讨了明湖水库库区水体在静置期和交换期的水质情况。结果表明:库容较大时,库区水体水环境容量较高,水质浓度的增加幅度较小;COD浓度随水体静置时间增加的幅度较NH3-N低;在水体静置期,库区水体停留时间以27~30 d为宜;明湖水库运行期间,通过支鱼港补水闸、大尖闸与大冲闸联合调度运行,相机换水可有效保证库区水质安全。     

基于WQImin模型的武汉市金银湖水质时空特性

为确定武汉市金银湖水域水质状况,提出水质评价报告,对武汉市金银湖7个水系10个典型水质指标的时空变化特征进行研究,建立了包含五日生化需氧量(BOD₅)、高锰酸盐指数(PI)、化学需氧量(COD)和溶解氧(DO)的4个主要污染指标的水质指数模型(WQI_min)。结果表明:①金银湖水质空间分布特征差异较大;位于其上游的东银湖、上金湖和墨水湖属于水质较差的污染区域(WQI_min=25.63~31.79);位于金银湖下游的东大湖、下金湖、下银湖和上银湖属于水质中等的低污染区域(WQI_min=45.64~53.19)。②金银湖水质时间格局分为3段:2019年1月水质状况最佳(WQI_min=61.68);2018年8月—2019年3月(2019年1月除外)为低污染时期(WQI_min=47.17~52.70);2019年4—10月份为水质较差的污染时期(WQI_min=24.41~35.95)。③2019年8—9月份与2018年同期相比水质下降,其原因应为外源和内源污染物的排放增长,金银湖水体治理管控需进一步加强。     

浅议上海饮用水水源及处理后水质

在调查和分析研究的基础上 ,对长江和黄浦江原水及其处理后水质进行了比较 ,长江原水及其常规处理后水质均明显优于黄浦江原水和出厂水。建议优先采用长江水源 ;对以黄浦江为原水的水厂的工艺流程进行改造 ,即增加生物预处理和 (或 )活性炭后处理设施。     

基于水质指数法的城市河流水质综合评价研究

依据江门市泥海水水质2020年9月的5个断面的监测数据,以溶解氧(DO)、高锰酸盐指数(CODMn)、化学需氧量(COD)、氨氮(NH3-N)、总磷(TP)作为CWQI模型的5个主要变量对河道水质进行综合评价.分析结果表明:各监测点的CODMn和 COD均满足Ⅳ类水质要求,TP基本满足Ⅳ类水质要求,DO污染较为严重,N...     

官厅水库饮用水源功能恢复对策

改善官厅水库水质应采取综合治理措施.对官厅水库上游流域重点企业实施治理,实现污水达标排放,在城镇污水集中地区建污水处理厂,使流入河道的水体得到净化,在水库及周边地区采取工程技术与生物生态技术相结合的措施.尽快恢复官厅水库饮用水源功能,缓解首都水资源紧缺状况.     

应用新型水质分析仪快速检测农村饮用水中的硫酸盐

针对宁夏中南部地区农村供水水质中普遍存在的硫酸盐含量检测问题,结合科研课题引进便携式水质分析仪进行快速检测,并与国标法相对照,获得满意的效果。     

小区优质饮用水配水管网设计浅谈

通过常州市某住宅小区优质饮用水配水管网的设计实例 ,探讨了解决管道二次污染问题 ,所采取的一些技术措施。设计中管网按全循环设置 ,采用大流量、定时循环运行的方法杀菌、消毒。     

内梅罗指数法在水质评价中存在问题及修正

根据内梅罗指数评价公式,分析了内梅罗指数法进行水质评价存在的问题并进行了修正,解决了原方法在水质评价中的数值不连续的局限性,地下水综合评分值仅受极大值的影响而与Fave关系甚微的弊端,以及原内梅罗指数计算值因相对集中而缺失"较好"水质级别的问题。应用修正前后的内梅罗指数法,对研究区地下水水质评价结果表明,修正后的内梅罗指数法在评价的水质状况时,更能反映真实情况。     

以水资源核算体系为基础的水利统计指标体系浅议

从绿色GDP与水资源核算体系的发展背景出发,分析水资源核算的指标体系,在此基础上探讨目前水利统计指标体系存在的问题。并以水资源核算体系的建立为契机,提出水利统计指标体系改革的方向。     

标识指数法在韩江下游主要饮用水源水质评价中的应用

介绍水质标识指数法的基本原理,并利用该方法分析评价2009年韩江下游主要饮用水源水质,给出水源保护措施。     

呼市自备井生活供水系统水质污染及防治对策

根据对代表性自备井供水单位的水质抽样化验结果及自来水公司供水系统的水质监测数据 ,对比分析了呼和浩特市自备井生活供水系统的水质污染现状和主要原因 ,提出了相应的防治对策。     

Ensemble Decision Tree Models Using RUSBoost for Estimating Risk of Iron Failure in Drinking Water Distribution Systems

Safe, trusted drinking water is fundamental to society. Discolouration is a key aesthetic indicator visible to customers. Investigations to understand discolouration and iron failures in water supply systems require assessment of large quantities of disparate, inconsistent, multidimensional data from multiple corporate systems. A comprehensive data matrix was assembled for a seven year period across the whole of a UK water company (serving three million people). From this a novel data driven tool for assessment of iron risk was developed based on a yearly update and ranking procedure, for a subset of the best quality data. To avoid a ‘black box’ output, and provide an element of explanatory (human readable) interpretation, classification decision trees were utilised. Due to the very limited number of iron failures, results from many weak learners were melded into one high-quality ensemble predictor using the RUSBoost algorithm which is designed for class imbalance. Results, exploring simplicity vs predictive power, indicate enough discrimination between variable relationships in the matrix to produce ensemble decision tree classification models with good accuracy for iron failure estimation at District Management Area (DMA) scale. Two model variants were explored: ‘Nowcast’ (situation at end of calendar year) and ‘Futurecast’ (predict end of next year situation from this year’s data). The Nowcast 2014 model achieved 100% True Positive Rate (TPR) and 95.3% True Negative Rate (TNR), with 3.3% of DMAs classified High Risk for un-sampled instances. The Futurecast 2014 achieved 60.5% TPR and 75.9% TNR, with 25.7% of DMAs classified High Risk for un-sampled instances. The output can be used to focus preventive measures to improve iron compliance.     

桐乡市改善自来水水质的对策初探

对桐乡市现有水厂原水、出厂水水质做出分析,提出了积极寻找优质的水源和强化水处理工艺来改善自来水水质的两个对策,并进行了多方案的技术经济比较。     

深圳市管道直饮水系统设计探讨

结合深圳市管道直饮水的现状 ,从用水定额、净水处理工艺、管网系统、管材的选用等方面阐述了管道直饮水系统设计的一些特点及经验