Multi-objective Coverage-based ACO Model for Quality Monitoring in Large Water Networks

A numerical procedure is presented for the optimization of the position of water quality monitoring stations in a pressurized water distribution system (WDS). The procedure is based on the choice of the set of sampling stations which maximizes the monitored volume of water while keeping the number of stations at minimum. The optimization model is formulated in terms of integer programming, and the solution of the mathematical problem is efficiently approximated by means of a multi-objective multi-colony ant algorithm. A built-in routine is developed for calculation of the water fraction matrix and integrated into the general modeling structure to facilitate data entry and storage to minimize problems associated with water fraction matrix determination for varying scenarios and coverage criteria for any scenario. The proposed methodology is very robust in analyzing the effects of different scenarios and/or number of potential monitoring stations by eliminating the need of employing an off-line routine for coverage matrix identification. Robustness, ease of generalization, multi-objective nature, and computational efficiency are the main characteristics and novelty of the proposed approach. Monitoring stations are optimally located in a large-scale real-world network with 104 nodes and multiple demands using the proposed ACO models. The set of non-dominated solutions forming the Pareto front for a number of monitoring stations and the total coverage of the system are also presented.     

Entropy-Based Sensor Placement Optimization for Waterloss Detection in Water Distribution Networks

The work presented herein addresses the problem of sensor placement optimization in urban water distribution networks by use of an entropy-based approach, for the purpose of efficient and economically viable waterloss incident detection. The proposed method is applicable to longitudinal rather than spatial sensing, thus to devices such as acoustic, pressure, or flow sensors acting on pipe segments. The method utilizes the maximality, subadditivity and equivocation properties of entropy, coupled with a statistical definition of the probability of sensing within a pipe segment, to assign an entropy metric to each pipe segment and subsequently optimize the location of sensors in the network based on maximizing the total entropy in the network. The method proposed is a greedy-search heuristic.     

严格水质监测保证水库供水安全

南黄壁庄水库是重要水源地,严格控制污水排放,实行水质监测,提高用水效率,为河北省的城市生活、工业和农业等用水提供保障.     

Optimal Design of Water Distribution Networks Considering Fuzzy Randomness of Demands Using Cross Entropy Optimization

This paper presents cross entropy (CE) optimization for optimal design of water distribution networks (WDN) under demand uncertainty. In design of WDNs, it is desired to achieve a minimum cost WDN that provides higher reliability in meeting the demands. To achieve these goals, an optimization model is formulated for design of WDNs with an objective of minimizing the total cost of WDN subject to meeting the nodal demands at a specified system reliability, mass conservation and other physical constraints. The uncertainty in future water demands is modeled using the theory of fuzzy random variable (FRV). The water demand at each node is assumed to be following a normal distribution with a fuzzy mean, and 10 % (or 20 %) of the fuzzy mean as its standard deviation. The water demand is represented as a triangular fuzzy number with the random demand as its kernel, and the interval of ±5 % (or ±10 %) variation of the random demand as its support for two scenarios. The fuzzy random system reliability (R) of WDNs is defined on the basis of necessity measure to assess system performance under fuzzy random demands and crisp head requirements. The latin hypercube sampling method is adopted for sampling of uncertain demands. The methodology is applied to two WDNs, and optimization models are solved through cross entropy optimization for different levels of reliability, and generated tradeoffs between the cost and R. On comparing the solutions obtained with the proposed methodology with earlier reported solutions, it is noted that the proposed method is very effective in producing robust optimal solutions. On analyzing the tradeoffs between reliability and costs, the results show that negligence of uncertainty can lead to under design of the WDNs, and the cost increases steeply at higher levels of reliability. The results of the two case studies demonstrate that the presented CE based methodology is effective for fuzzy-probabilistic design of WDNs.     

八一水库水质模糊综合评价

模糊综合评价法是一种基于模糊数学的综合评价方法,是用模糊数学方法对受到多种因素制约的事物或对象做出一个总体的评价。在水质评价中应用时,模糊综合评价法考虑到了水质分级界限的模糊性和污染因素的权重,能够客观地反映水体的水质现状,其评价结果具有较强的代表性,是一种客观、有效的水质定量评价方法。     

Assessment of Sustainability in Water Supply-Demand Considering Uncertainties

Water is a vital resource for life on earth; hence its maintenance is very important. Different regions especially in arid and semi-arid areas are facing population growth and subsequent increase in the domestic, industrial and agricultural activities. Planning of water systems in order to be ready for future development conditions needs further studies on the estimation of the sustainable levels of demands based on the sustainable levels of supplies. In this study a threefold approach for estimating sustainability level of supply and demand in Ahachay river basin in northwestern part of Iran as a case study is taken. In the first method, the internal flows and the origins and final uses of the total resources for each subsystem are estimated and planning for sustainability use index is determined by calculating the available water. Second method introduced a simulation model which is utilized to estimate reliability, resiliency, vulnerability and maximum deficit for a river basin to determine a group sustainability index. In the third method, for evaluating the movement toward sustainability, an index is developed. This index includes parameters that are the difference between supply and demand, percentage of the satisfied demand, productivity of water resources and an indicator for evaluating the reduction of aquifer storage. Finally these methods are compared and a hybrid index combining the indices is developed. An uncertainty analysis is also performed to investigate the random nature of variables in estimating water balance and quantifying the water sustainability. This hybrid index can be used for evaluating the planning scenarios and for maintaining and improving the sustainable state of supply-demand for the region.     

契爷石水库水质监测评价及水质预测研究

契爷石水库开展了6年(2015—2020年)的水质监测.结果表明:溶解氧、高锰酸盐指数、日生化需氧量和氨氮表现出明显的季节性变化特征,而总氮和总磷没有表现出明显的季节性特性;溶解氧随年份呈先减小后增大规律,高锰酸盐指数和五日化学需氧量没有明显规律性,氨氮、总氮和总磷在整体上呈递减趋势;采用综合水质评价法和模糊综合评价法对水库水质进行综合评价,评价结果均达到生活用水和灌溉用水要求的最低Ⅲ类标准;GM(1,1)灰色预测模型对水库水质指标的平均预测误差为9.8％,预测效果较好,可用于该水库未来一段时间内水质的预测分析.     

大伙房水库监测断面水质特征分析

基于SPSS16．0统计软件,采用主成分分析法对大伙房水库2000-2003年的北杂木、古楼、台沟3个监测断面的16项水质指标数据进行处理,从原始监测数据中提取出2个主成分,并计算其贡献率和3个监测断面的主成分值。2个主成分中各水质指标的载荷值表明．浑河污染主要受上游工业企业污染及沿河农业污染的影响,苏子河受养殖业带来的影响污染较严重,社河污染主要为沿河农业生产带来的污染。从水质污染综合评价得分年际变化来看,浑河有污染加重的趋势,苏子河、社河水质有显著提升。该文针对各河流水质特征提出了环境管理办法。     

A Novel Stochastic Approach for Optimization of Diversion System Dimension by Considering Hydrological and Hydraulic Uncertainties

Water Resources Management - This study proposes a new stochastic approach for optimizing diversion system design and its construction schedule by considering different hydrological and hydraulic...     

An Optimization Strategy for Water Distribution Networks

An optimization strategy based on head losses minimization is developed for the least cost design of water distribution networks. A new weighting approach is suggested for calculating the initial flow distribution and optimum pipe diameters of the weighted flow distribution is presented by using least square method. In the mean time homogenous and isotropous head losses are maintained with implications of head loss path choice. The model is employed for designing and/or modifying pipe sizes while the classical Hardy-Cross network solver is used to balance the flows. The whole algorithm is programmed and applied to a two-looped network selected from the literature and the results are presented on a comparative basis. A FORTRAN software with the necessary steps in the flow chart is written for the optimization calculations in this paper.     

Spatio-Temporal Multi-Criteria Optimization of Reservoir Water Quality Monitoring Network Using Value of Information and Transinformation Entropy

Identifying optimal Water Quality Monitoring Stations (WQMS) with high values of information on the entire reservoir status, instead of all potential WQMS would significantly reduce the monitoring network expenditure while providing adequate spatial coverage. This study presented a new methodology for spatio-temporal multi-criteria optimization of reservoir WQMS based on Value of Information (VOI), Transinformation Entropy (TE), Non-dominated Sorting Genetic Algorithm II (NSGA-II), Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE), and IRanian Water Quality Index (IRWQI). Although, all mentioned methods and concepts are well-known and have been used in water resources management, but their integration into a specific application for spatio-temporal multi-criteria optimization of reservoir WQMS is definitely an innovation and a contribution to improvement of WQMS design. More specifically, maximizing VOI as a decision-makers’ design criteria for optimization of WQMS, and considering spatial and temporal variations of water quality at different reservoir depths are new innovations in this research. The multi-objective optimization model was based on three objectives: 1) minimizing costs; 2) maximizing VOI; and 3) minimizing TE (redundant information). Considering these objectives, the NSGA-II multi-objective optimization method was used to find Pareto-optimal solutions. The most preferable solution was then determined using PROMETHEE multi-criteria decision making method. The proposed methodology was applied to Karkheh Reservoir with more than 5 billion cubic meter capacity and 60 km length that is one of the largest reservoirs in Southwestern Iran, however, the proposed approach has the ability to be generalized for any generic reservoir. Considering equal weights for criteria, PROMETHEE method resulted in 6 optimized WQMS out of 60 potential ones and a period of 25 days for optimal sampling interval. The optimized monitoring stations were mainly located at deep parts where most water quality variations are expected to occur. To show sensitivity of the model to different weights, 4 scenarios with various relative weights were evaluated in the PROMETHEE method. Results indicated that by increasing the weight of the second criterion (maximizing VOI), the number of optimized WQMS increased and the sampling interval decreased.     

丹江口水库水质的遥感监测

丹江口水库作为南水北调中线工程的水源地,其水质安全将直接影响到调水工程的成败。根据丹江口库区2012年3月25日和8月9日的两幅HJ卫星遥感影像,结合同步的实测水质参数,采用经验反演模型对丹江口水库叶绿素a(Chl_a)浓度、总磷(TP)浓度和水体透明度(SD)进行了定量反演研究。结果显示,无论是枯水期和丰水期,丹库和汉库入库口的Chl_a浓度和TP浓度都要高于其他区域,而入库口区域的SD要低于其他区域。通过分析14项实测水质指标的主成分分析结果和丹江口库区LULC遥感解译结果发现,枯水期库区TP主要来源于库区上游城镇生活污水和工业废水,而丰水期TP主要来自于农业面源污染。SD反演结果还显示,由于汉江上游降雨量大,水土流失严重,使得汉库水体透明度明显低于丹库。利用Chl_a反演结果对丹江口水库的水体营养状态进行分析后发现,在丹库、汉库入库口区域以及水体流通性较小的狭小水体,水库水体达到了轻度富营养化状态,因此,应该加强对库区面源污染的控制和生态环境修复。     

模糊优选ANN在水库调度方案优选中的应用

综合利用水库洪水调度决策是一个复杂决策过程。由于其精确优化解很难找到,因此从可行方案集中找出最优方案已成为当今研究的主要问题。在分析综合利用水库洪水调度特点及现有水库调度方法存在的问题的基础上,将模糊优选理论与ANN模型应用到调度方案优选当中。给出生成模糊优选ANN模型训练样本和方案优选的方法,并将其应用到辽宁省大伙房水库洪水调度方案优选之中。应用结果表明该方法简单、可行。     

水库长期优化调度模型探讨

在水库长期优化调度问题中,一般以发电量最大为优化调度模型。考虑到电力市场的影响,综合水电站水库自身约束和电力系统调峰要求,建立以水电站发电效益最大为目标的优化调度模型,并通过实例计算比较这两种模型,发电效益最大模型较发电量最大模型更为符合实际。     

册田水质自动监测系统的建设与运行

在省界断面和主要监测断面设立水质自动监测站,对断面水质进行实时监控,具有十分重要的意义.文中主要介绍水利部"21世纪初期首都水资源可持续利用规划"建设项目--册田水质自动监测系统的组成和软件框架,详细介绍了系统的验收、运行和维护.册田水质自动监测系统采用了新式的取水方式,具有水质综合评价的高级应用功能及提供第三方软件开发等最新功能.该系统的建成可以有效控制水库污染、保证首都人民用水安全.     

基于分层监测的水库水质时空变化特征研究

为解决以往水质监测数据多是针对表层水体采样,难以完整的反映水库水质状况的问题,本文以碧流河水库为研究对象,根据其水文及地形条件从水库上游至坝前依次选取六个监测断面,采用分层监测的方式对水库水质进行监测,利用GIS地统计学方法和图片展示功能对碧流河水库的温度、溶解氧、总氮及总磷的垂向分层分布状态进行分析,直观的展示出动态水位下的水库垂向深度变化及其相应的水质属性。结果表明水库总氮呈现均匀混合状态;水库总磷呈现汛期大,汛后小,冬季最低的变化特征,平面分布上呈现水力推移的特征,随着水力方向逐渐减少,垂向上则无明显分层现象。     

西丽水库水质监测系统的设计与实现

介绍水质自动监测技术。着重介绍了西丽水库水质自动监测系统的设计，通过构建水质自动化监测系统，从而实现对水库原水水温、PH值、溶解氧、浑浊度、氨氮等参数的自动监测。     

Multi-Source Multi-Sector Sustainable Water Supply Under Multiple Uncertainties: An Inexact Fuzzy-Stochastic Quadratic Programming Approach

This paper presents the development and the first application of a superiority–inferiority-based inexact fuzzy-stochastic quadratic programming (SI-IFSQP) approach for sustainable water supply under multiple uncertainties. SI-IFSQP improves conventional nonlinear programming by tackling multiple uncertainties within an individual parameter; SI-IFSQP is also superior to existing inexact methods due to its reflection of economies of scale and reduction of computational requirements. An interactive solution algorithm with high computational efficiency was also proposed. The application of SI-IFSQP to long-term planning of a multi-source multi-sector water supply system demonstrated its applicability. The close reflection of system complexities, such as multiple uncertainties, scale economies and dynamic parameters, could enhance the robustness of the optimization process as well as the acceptability of obtained results. Corresponding to varied system conditions and decision priorities, the interval solutions from SI-IFSQP could help generate a series of long-term water supply strategies under a number of economic, environmental, ecological, and water-security targets.     

Application of Information Theory to Groundwater Quality Monitoring Networks

Using the criteria of maximizing information and minimizing cost,a methodology is developed for design of an optimal groundwater-monitoring network for water resources management. A monitoring system is essentially an information collection system. Therefore, its technical design requires a quantifiablemeasure of information which can be achieved through applicationof the information (or entropy) theory. The theory also providesinformation-based statistical measures to evaluate the efficiencyof the monitoring network. The methodology is applied to groundwater monitoring wells in a portion of Gaza Strip in Palestine.     

应用一维水动力学模型预测三峡水库蓄水位

三峡水库是河道型水库,以常规的静库容方法推算库区水位变化误差较大,有必要应用水动力学模型进行计算。建立了基于一维非恒定流的水动力学模型,模拟库区河道水流演进过程,预测三峡坝前的水位、流量过程。选取2007年9月25日至10月3日的三峡水库蓄水资料进行计算,并与实测水位比较。结果表明,该模型具有较好的精度,能够为实际蓄水调度提供参考。