Este trabalho apresenta o dimensionamento otimizado de redes pressurizadas de distribuição de água em regime permanente para áreas de topografia relativamente plana. Além dos critérios tradicionais de dimensionamento hidráulico, o resultado ótimo é aquele com menor custo global, ou seja, onde a soma dos custos de implantação e de operação é mínimo. Para a determinação dos resultados, as equações que envolvem a perda de carga nos circuitos e vazões em cada nó foram solucionadas através da programação não linear com emprego de métodos matriciais. As principais variáveis analisadas foram os diferentes materiais das tubulações (PEAD, PVC e Ferro Fundido), tipos de superfície (terra, concreto, paralelepípedo e asfalto), locação da rede (passeio, viário pavimentado e sem pavimentação), tarifas de energia elétrica para concessionárias de água, vida útil usuais para o sistema de bombeamento e taxa de juros ao longo da operação do sistema. Os resultados obtidos através da metodologia proposta demonstraram que as principais variáveis em relação ao custo referencial unitário foram o custo da pressurização inicial, custo da tubulação, além do custo de remoção e recomposição de viário em pavimento asfáltico. / This work presents the optimal design of pressurized networks of water distribution in steady state flow to areas of relatively flat topography. In addition to the traditional hydraulic criteria for design, the optimal outcome is that with lower overall cost, in other words, where the sum of the costs of implementation and operation is minimal. To obtain the results, the equations that involving headloss in the circuits and flows at each node were solved by nonlinear programming with the use of matrix methods. The main variables studied were the different materials of pipes (HDPE, PVC and Cast Iron), surface types (clay, concrete and asphalt paving), network location (walk, paved and unpaved road), electricity tariffs for water utilities, normal life for the pumping system and interest rates along the system operation. The results obtained by the proposed methodology showed that the main variables in relation to the unit cost were the cost of initial pressurization, cost of the pipe, besides the cost of removal and restoration of roads in asphalt pavement.

O presente trabalho apresenta um plano de substituição de tubulações do sistema de distribuição de água da Região Metropolitana de São Paulo (RMSP), utilizando um sistema de informações geográficas (SIG), que permitiu o relacionamento de dados do cadastro físico das tubulações com informações de reparos de vazamentos. Foram criados grupos de tubulações de mesmo material e, em alguns casos, de um mesmo período de implantação, para a definição de taxas anuais de substituição a partir da previsão de quebras futuras e da determinação do tempo ótimo de substituição das tubulações. Os resultados obtidos indicam que a vida média das tubulações apresenta um valor inferior ao verificado em países desenvolvidos. Assim, a taxa anual de substituição de tubulações, devendo oscilar entre 1,25 e 2%, será superior à média dos países desenvolvidos, que gira em torno de 0,5 a 1%, considerando que a idade média das tubulações varie entre 100 e 200 anos. / The following study presents a pipes replacement plan for the water distribution system of the Metropolitan Region of Sao Paulo (MRSP), using a geographic information system (GIS), which allowed the relation between the data of the water mains and the information about leakage repairs. Water main groups of the same material were created and, in some cases, of the same installation period, for the definition of yearly replacement rates based on the future breaks forecast and determination of the water mains optimal replacement timing. The results obtained suggest that the water mains average life, show a lower value than the one verified in developed countries. Thus, the water mains year replacement rate, witch should range from 1.25 to 2%, will be higher than the average in developed countries, witch is about 0.5 and 1%, considering that water mains mean age varies between 100 and 200 years.

Este trabalho apresenta o dimensionamento otimizado de redes pressurizadas de distribuição de água em regime permanente para áreas de topografia relativamente plana. Além dos critérios tradicionais de dimensionamento hidráulico, o resultado ótimo é aquele com menor custo global, ou seja, onde a soma dos custos de implantação e de operação é mínimo. Para a determinação dos resultados, as equações que envolvem a perda de carga nos circuitos e vazões em cada nó foram solucionadas através da programação não linear com emprego de métodos matriciais. As principais variáveis analisadas foram os diferentes materiais das tubulações (PEAD, PVC e Ferro Fundido), tipos de superfície (terra, concreto, paralelepípedo e asfalto), locação da rede (passeio, viário pavimentado e sem pavimentação), tarifas de energia elétrica para concessionárias de água, vida útil usuais para o sistema de bombeamento e taxa de juros ao longo da operação do sistema. Os resultados obtidos através da metodologia proposta demonstraram que as principais variáveis em relação ao custo referencial unitário foram o custo da pressurização inicial, custo da tubulação, além do custo de remoção e recomposição de viário em pavimento asfáltico. / This work presents the optimal design of pressurized networks of water distribution in steady state flow to areas of relatively flat topography. In addition to the traditional hydraulic criteria for design, the optimal outcome is that with lower overall cost, in other words, where the sum of the costs of implementation and operation is minimal. To obtain the results, the equations that involving headloss in the circuits and flows at each node were solved by nonlinear programming with the use of matrix methods. The main variables studied were the different materials of pipes (HDPE, PVC and Cast Iron), surface types (clay, concrete and asphalt paving), network location (walk, paved and unpaved road), electricity tariffs for water utilities, normal life for the pumping system and interest rates along the system operation. The results obtained by the proposed methodology showed that the main variables in relation to the unit cost were the cost of initial pressurization, cost of the pipe, besides the cost of removal and restoration of roads in asphalt pavement.

O trabalho apresenta uma descrição da estrutura de um sistema de controle de reservatórios em tempo real e as diversas formas de controle existentes, mostrando a necessidade de otimização e automatização do controle. São descritas as experiências de controle operacional baseado em computador obtidas da bibliografia. É apresentado o estado da arte na modelação da operação, no que diz respeito a simulação, otimização e previsão de demandas. E apresentado o sistema adutor metropolitano de São Paulo e descrito o seu sistema de controle operacional. São discutidos dois modelos alternativos propostos para a previsão de consumos em tempo real, baseados em ajustes polinomiais e harmônicos das séries de dados. Analisam-se os resultados de aplicação prática destes modelos quanto a precisão de resultados e a confiabilidade de operação. / This work describes the structure of a reservoir system control in real time. Several usual types of control are shown, focusing on the need for optimization and automation of real time operations. Experiences on operational control based on computer referred in literature are described. The state-of-art of operation modeling concerning to simulation, optimization and demand forecasting is presented. The Metropolitan System of Water Distribution of São Paulo and its operational control system are described. Two proposed models for water demand forecasting in real time are discussed. The first one is based on the concept of polynomial adjustement to water consumption data. The other one uses an harmonic representation of the observed values. Results of practical application of these models are analyzed, in respect of numerical precision and confidence on operational decisions.

Previous efforts to apply risk analysis for water distribution systems (WDS) have not typically included explicit hydraulic simulations in their methodologies. A risk classification scheme is here employed for identifying vulnerable WDS components subject to an intentional water contamination event. A Monte Carlo simulation is conducted including uncertain stochastic diurnal demand patterns, seasonal demand, initial storage tank levels, time of day of contamination initiation, duration of contamination event, and contaminant quantity. An investigation is conducted on exposure sensitivities to the stochastic inputs and on mitigation measures for contaminant exposure reduction. Mitigation measures include topological modifications to the existing pipe network, valve installation, and an emergency purging system. Findings show that reasonable uncertainties in model inputs produce high variability in exposure levels. It is also shown that exposure level distributions experience noticeable sensitivities to population clusters within the contaminant spread area. The significant uncertainty in exposure patterns leads to greater resources needed for more effective mitigation.

In a water distribution system from groundwater supply, the bulk of energy consumption is expended at pump stations. These pumps pressurize the water and transport it from the aquifer to the distribution system and to elevated storage tanks. Each pump in the system has a range of possible operating conditions with varying flow rates, hydraulic head imparted, and hydraulic efficiencies. In this research, the water distribution system of a mid-sized city in a subtropical climate is modeled and optimized in order to minimize the energy usage of its fourteen pumps. A simplified model of the pipes, pumps, and storage tanks is designed using freely-available EPANET hydraulic modeling software. Physical and operational parameters of this model are calibrated against five weeks of observed data using a genetic algorithm to predict storage tank volume given a forecasted system demand. Uncertainty analysis on the calibrated parameters is performed to assess model sensitivity. Finally, the pumping schedule for the system's fourteen pumps is optimized using a genetic algorithm in order to minimize total energy use across a 24-hour period.

Threat management of water distribution systems is essential for protecting consumers. In a contamination event, different strategies may be implemented to protect public health, including flushing the system through opening hydrants or isolating the contaminant by manipulating valves. To select the most effective options for responding to a contamination threat, the location and loading profile of the source of the contaminant should be considered. These characteristics can be identified by utilizing water quality data from sensors that have been strategically placed in a water distribution system. A simulation-optimization approach is described here to solve the inverse problem of source characterization, by coupling an evolutionary computation-based search with a water distribution system model. The solution of this problem may reveal, however, that a set of non-unique sources exists, where sources with significantly different locations and loading patterns produce similar concentration profiles at sensors. The problem of non-uniqueness should be addressed to prevent the misidentification of a contaminant source and improve response planning. This paper aims to address the problem of non-uniqueness through the use of Niched Co-Evolution Strategies (NCES). NCES is an evolutionary algorithm designed to identify a specified number of alternative solutions that are maximally different in their decision vectors, which are source characteristics for the water distribution problem. NCES is applied to determine the extent of non-uniqueness in source characterization for a virtual city, Mesopolis, with a population of approximately 150,000 residents. Results indicate that NCES successfully identifies non-uniqueness in source characterization and provides alternative sources of contamination. The solutions found by NCES assist in making decisions about response actions. Once alternative sources are identified, each source can be modeled to determine where the vulnerable areas of the system are, indicating the areas where response actions should be implemented.

Water distribution system modeling can be used as a basis of planning and operation decisions. However, model accuracy and uncertainty will impact the model based decisions. Model prediction uncertainty results from uncertainty in model parameters that are determined through calibration or are based upon modeler judgment. The focus of this dissertation is the effect of uncertainties on water quality model estimates and calibration. The dissertation is centered around three journal articles and a technical note.In the first paper, the effect of parameter uncertainty on water quality in a distribution system under steady and unsteady conditions was analyzed by Monte Carlo simulation (MCS). Sources of uncertainties for water quality include decay coefficients, pipe diameter and roughness, and nodal spatial and temporal demands. The effect of individual parameter is discussed, as well as the combined effect of the parameters. It also describes the effect of flow patterns.A general calibration model is developed in the second paper for identifying wall decay coefficients. The problem is solved using the SFLA optimization algorithm that is coupled with hydraulic and water quality simulation models using the EPANET toolkit. The methodology is applied on two application networks. The study presents the effect of different field conditions such as the network with or without tanks, altering disinfectant injection policies, changing measurement locations, and varying the number of global wall decay coefficient on the estimated parameters. The numerical study also discusses whether the complexity of the system can be captured with fewer than the actual number of field parameters and if the number of the measurement locations is sufficient.The third paper conducts a study that considers a full calibration assessment for a water quality model in the distribution systems. The calibration process begins with estimating the the best fit wall decay coefficients. Next, the uncertainties involved with estimated parameters are calculated. Finally, the study assesses the model prediction uncertainties for critical demand conditions due to the parameter uncertainties. Various conditions are evaluated including the effects of different measurement errors and different measurement conditions on the uncertainty levels of estimated parameters as well as on the model predictions.Fourth paper presents study in which a booster disinfectant is introduced within a distribution system to maintain disinfectant residuals and avoid high dosages at water sources. Assuming that first order reaction kinetics apply to chlorine decay, an integer linear programming optimization problem is posed to booster locations and their injection rates. The formulation avoids long water quality simulations by adding constraints requiring the concentrations at the beginning and end of the design period to be the same. The optimization problem is divided into two levels. The upper level selects the booster locations using a genetic algorithm, if more than a few boosters are included, or enumeration, if the number of boosters and/or potential locations is relatively small. Given a set of boosters from the upper level, the lower level minimizes the chlorine mass to be injected to maintain required residuals. The approach is applied to the Brushy Plains system for alternative numbers of allowable boosters.

Municipal water distribution system (WDS) expansion is often focused on increasing system capacity with designs that best meet hydraulic requirements at the least cost. Increasing public awareness regarding global warming and environmental degradation is making environmental impact an important factor in decision-making for municipalities. There is thus a growing need to consider environmental impacts alongside cost and hydraulic requirements in the expansion and design of WDSs. As a result, the multiplicity of environmental impacts to consider in WDS expansion can complicate the decisions faced by water utilities. For example, a water utility may wish to consider environmental policy issues such as greenhouse gas emissions, non-renewable resource use, and releases to land, water, and air in WDS expansion planning. This thesis outlines a multi-objective optimization approach for WDS design and expansion that balances the objectives of capital cost, annual pumping energy use, and environmental impact minimization, while meeting hydraulic constraints. An environmental impact index that aggregates multiple environmental measures was incorporated as an environmental impact objective function in the multi-objective non-dominated sorting genetic algorithm-II (NSGA-II) optimization algorithm. The environmental impact index was developed to reflect stakeholder prioritization of specific environmental policy issues. The evaluation of the environmental impact index and its application to the WDS expansion problem was demonstrated with a water transmission system example. The environmental impact index and multi-objective non-dominated sorting genetic algorithm-II (NSGA-II) optimization algorithm were applied to the “Anytown” network expansion problem. Preliminary results suggest that solutions obtained with the triple-objective capital cost/energy/EI index optimization minimize a number of environmental impact measures while producing results that are comparable in pumping energy use and, in some instances, slightly higher in capital cost when compared to solutions obtained with a double cost/energy optimization in which environmental impact was not considered. / Thesis (Master, Civil Engineering) -- Queen's University, 2009-08-25 16:08:33.636

In response to growing environmental concerns, policy makers in Canada have been developing climate change mitigation strategies that will enable Canada to meet medium and long-term greenhouse gas (GHG) emission reduction targets. The water industry is energy- and carbon-intensive, thus the magnitude and long-term uncertainty of proposed carbon mitigation policies could have implications for water distribution system capital planning decisions that are made today. The intent of this thesis was to examine the implications of discount rate and carbon price uncertainty on cost, energy use and GHG emissions in the design/optimization of the Amherstview water distribution system in Loyalist Township, Ontario, Canada. A non-dominated sorting genetic algorithm is coupled with the hydraulic solver EPANET2 in a single-objective optimization approach to identify network expansion designs that minimize total cost as the sum of: i) capital cost of installing new and parallel pipes and of cleaning and lining existing pipes; ii) operation cost of electricity for pumping water; and iii) carbon cost levied on electricity used for pumping water. The Amherstview system was optimized for a range of discount rates and carbon prices reflective of possible climate change mitigation strategies in Canada over the next 50 years. The problem formulation framework was developed according to a “real-world” municipal approach to water distribution system design and expansion. Decision variables such as pipe sizes are restricted to “real-world” commercially-available pipe diameters and parameter values are chosen according to engineering judgment and best-estimates. Parameter uncertainty is characterized by sensitivity analysis rather than the more computationally-demanding and data-intensive Monte Carlo simulation method. The impact of pipe material selection on energy use and GHG emissions was investigated for polyvinyl chloride and cement-mortar lined ductile iron pipes. Results from this first-ever study indicate that the discount rate and carbon prices investigated had no significant influence on energy use and GHG emissions in the Amherstview system. Pipe material selection was also found to minimally affect the amount of GHG emitted in the Amherstview system. / Thesis (Master, Civil Engineering) -- Queen's University, 2010-08-26 15:01:27.174