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[EN] In this contribution, a nonlinear programming genetic hybrid algorithm for the optimal design of pressurized irrigation networks operating in shifts is presented, and an indicator is implemented to evaluate the flexibility of the resulting designs of the hybrid algorithm. The main objective is the minimization of the economic cost of the pipe network and the evaluation of the flexibility of the system designs. The research considers the allocation of shifts to the irrigation outlets (hydrants) and the sizing of the pipes as decision variables to reduce implementation costs. With the results of the optimization, the flexibility of the hydraulic network is analyzed based on the random reassignment of shifts to the hydrants, which simulates the modifications that may occur during network operation. To validate the algorithm, once calibrated, it was applied to the design of four real irrigation sectors of Ecuador and Spain. The results indicate that the designs obtained improve in cost and flexibility with respect to those found with the traditional algorithm of the Economic Series, and that the assignment of the shifts is of utmost importance to minimize investment costs in pipes. At the same time, it constitutes a determining factor in the flexibility of the system., [ES] En esta contribución se presenta un algoritmo híbrido genético-programación no lineal para el diseño óptimo de redes presurizadas de riego operando a turnos, y se implementa un indicador para evaluar la flexibilidad de los diseños resultantes del algoritmo híbrido. El objetivo principal es la minimización del costo económico de la red de tuberías y la evaluación de la flexibilidad de los diseños del sistema. La investigación considera como variables de decisión la asignación de turnos a las tomas de riego (hidrantes) y el dimensionado de las conducciones para reducir los costos de implementación. Con los resultados de la optimización se analiza la flexibilidad de la red hidráulica con base en la reasignación aleatoria de turno a los hidrantes, que simula las modificaciones susceptibles de ocurrir durante la explotación de la red. Para validar el algoritmo, una vez calibrado, éste fue aplicado al diseño de cuatro sectores de riego reales de Ecuador y España. Los resultados indican que los diseños obtenidos mejoran en costo y flexibilidad respecto a los encontrados con el algoritmo tradicional de la serie económica, y que la asignación de los turnos es de suma importancia para minimizar los costos de inversión en tuberías, lo que a la vez constituye un factor determinante en la flexibilidad del sistema.

[EN] The excess pressure available in water distribution networks (WDNs) is a relevant aspect in the management and appropriate handling of water resources. If a WDN meets the minimum performance criteria (minimum pressure and maximum flow), excess pressure can occur throughout the day, which is usually lost. These excesses could be considered as potentially recoverable energy (PRE). One way of taking advantage of this energy is to find the nodes on the network where this excess pressure is evident and try to analyze the possible amount of PRE. This work presents a methodology to determine the maximum PRE in a WDN. This methodology includes the locations of the points where the installation of recovery devices leads to this maximum PRE. The method is based on reducing pressures but maintaining circulating points through the lines. Additionally, a new energy balance that allows visualizing and breaking down in more detail all the energy found in a WDN is proposed. The analysis is carried out in an extended period considering different feeding points either by gravity or pumping. Finally, a network resilience index called the Potentially Recoverable Energy Index (PREI) in WDNs is proposed, with which it is possible to diagnose and determine how much energy could be recovered from the network. Study cases presented demonstrate the effectiveness of the methodology and will allow the development of optimizations in the operation of WDNs in favor of the good management of water and energy resources.

[EN] Pumping station (PS) designs in water networks basically contemplate technical and economic aspects. Technical aspects could be related to the number of pumps in PS and the operational modes of PS. Meanwhile, economic aspects could be related to all the costs that intervene in a PS design, such as investment, operational and maintenance costs. In general, water network designs are usually focused on optimizing operational costs or investment costs, However, some subjective technical aspects have not been approached, such as determining the most suitable pump model, the most suitable number of pumps and the complexity of control system operation in a PS design. Therefore, the present work aims to select the most suitable pump model and determine the prior-ities that technical and economic factors could have in a PS design by a multi-criteria analysis, such as an analytic hierarchy process (AHP). The proposed work will contemplate two main criteria, and every criterion will be integrated by sub-criteria to design a PS. In this way, technical factors (number of pumps and complexity of the operating system) and economic factors (investment, operational and maintenance costs) will be considered for a PS design. The proposed methodology consists of realizing surveys to a different group of experts that determines the importance of one criterion over each other criterion in a PS design through pairwise comparisons. Finally, this methodology will provide importance weight for the criteria and sub-criteria on the PS. Besides, this work will perform a rating of the considered alternatives of pump models in every case study, evaluating quantitatively every alternative with every criterion in the PS design. The main objective of this work will select the most adequate pump model according to the obtained rating, considering technical and economic aspects in every case study.

[EN] A problem for drainage systems managers is the increase in extreme rain events that are increasing in various parts of the world. Their occurrence produces hydraulic overload in the drainage system and consequently floods. Adapting the existing infrastructure to be able to receive extreme rains without generating consequences for cities' inhabitants has become a necessity. This research shows a new way to improve drainage systems with minimal investment costs, using for this purpose a novel methodology that considers the inclusion of hydraulic control elements in the network, the installation of storm tanks and the replacement of pipes. The presented methodology uses the Storm Water Management Model for the hydraulic analysis of the network and a modified Genetic Algorithm to optimize the network. In this algorithm, called the Pseudo-Genetic Algorithm, the coding of the chromosomes is integral and has been used in previous studies of hydraulic optimization. This work evaluates the cost of the required infrastructure and the damage caused by floods to find the optimal solution. The main conclusion of this study is that the inclusion of hydraulic controls can reduce the cost of network rehabilitation and decrease flood levels.

[EN] In recent years, a significant increase in the number of extreme rains around the world has been observed, which has caused an overpressure of urban drainage networks. The lack of capacity to evacuate this excess water generates the need to rehabilitate drainage systems. There are different rehabilitation methodologies that have proven their validity; one of the most used is the heuristic approach. Within this approach, the use of genetic algorithms has stood out for its robustness and effectiveness. However, the problem to be overcome by this approach is the large space of solutions that algorithms must explore, affecting their efficiency. This work presents a method of search space reduction applied to the rehabilitation of drainage networks. The method is based on reducing the initially large search space to a smaller one that contains the optimal solution. Through iterative processes, the search space is gradually reduced to define the final region. The rehabilitation methodology contemplates the optimization of networks using the joint work of the installation of storm tanks, replacement of pipes, and implementation of hydraulic control elements. The optimization model presented uses a pseudo genetic algorithm connected to the SWMM model through a toolkit. Optimization problems consider a large number of decision variables, and could require a huge computational effort. For this reason, this work focuses on identifying the most promising region of the search space to contain the optimal solution and to improve the efficiency of the process. Finally, this method is applied in real networks to show its validity.

[EN] The control systems point to bring the pumping curve close to the set-point curve. That concept is essential for proper design of a pumping station. An adequate design is not only focused to select the total number of the pumps and select the type of control to use (flow or pressure), but also is im-portant to determine the optimal number of Fixed Speed Pumps (FSP) pumps and Variable Speed Pumps (VSP) pumps for each flow rate. This work will discuss the most common methods proce-dures for control systems on a design of pumping stations with a methodology that it is going to be proposed. This methodology consists on expressing the characteristics of the pumping curve and the set-point curve in a dimensionless form so that the methodology be standardized for any pump model and set-point curve. These formulations allow us to discuss how the characteristic of a pump and the set-point curve of the network influence to determine the optimal number of FSPs and VSPs in energy terms. In general, the objective of this work is to determine the most suitable total number of pumps in a pumping station design and determine the optimal pumping configuration in every flow rate, so the consumed energy be the minimum. Also, this methodology will develop an ex-pression to estimate the performance of a frequency inverter when a VSP operates at different ro-tational speeds. This work will be applied to different study cases and the obtained results allow us to question several usual procedures for pumping control system. In general, it can be concluded that the number of pumps of a pumping system cannot be inferred in a simple form without a deep analysis of a control system.

[EN] The pumping station are very important hydraulic system in urban water supply be-cause the pumps raise the water head ensuring the minimum pressure required in drinking water systems. In the design of a pumping station, one of the most important criteria is the number of pumps. However, in the traditional design this criterion is de-fined arbitrarily. The other criteria are defined from the number of pumps and can be produce a design not optimal. In addition, the traditional design does not consider the environment importance to choose the pumps. The objective of this paper is defining a new design methodology for pumping sta-tions. It has been developed using a multicriteria analysis in which nine criteria are evaluated. The application of the analytic hierarchy process (AHP) allows finding an optimal solution. These design criteria have been associated in three cluster factors: technical factors, environmental factors, and economic factors. The results obtained allow not only to validate the methodology, but also to offer a solution to the problem of determining the most suitable model and the number of pumps of a pumping sta-tion.

[EN] The investment and operating costs of pumping stations in drinking water distribution networks are some of the highest public costs in urban sectors. Generally, these systems are designed based on extreme scenarios. However, in periods of normal operation, extra energy is produced, thereby generating excess costs. To avoid this problem, this work presents a new methodology for the design of pumping stations. The proposed technique is based on the use of a setpoint curve to optimize the operating and investment costs of a station simultaneously. According to this purpose, a novel mathematical optimization model is developed. The solution output by the model includes the selection of the pumps, the dimensions of pipelines, and the optimal flow distribution among all water sources for a given network. To demonstrate the advantages of using this technique, a case study network is presented. A pseudo-genetic algorithm (PGA) is implemented to resolve the optimization model. Finally, the obtained results show that it is possible to determine the full design and operating conditions required to achieve the lowest cost in a multiple pump station network.

[EN] In this contribution, a nonlinear programming genetic hybrid algorithm for the optimal design of pressurized irrigation networks operating in shifts is presented, and an indicator is implemented to evaluate the flexibility of the resulting designs of the hybrid algorithm. The main objective is the minimization of the economic cost of the pipe network and the evaluation of the flexibility of the system designs. The research considers the allocation of shifts to the irrigation outlets (hydrants) and the sizing of the pipes as decision variables to reduce implementation costs. With the results of the optimization, the flexibility of the hydraulic network is analysed based on the random reassignment of shifts to the hydrants, which simulates the modifications that may occur during network operation. To validate the algorithm, once calibrated, it was applied to the design of four real irrigation sectors of Ecuador and Spain. The results indicate that the designs obtained improve in cost and flexibility with respect to those found with the traditional algorithm of the Economic Series, and that the assignment of the shifts is of utmost importance to minimize investment costs in pipes. At the same time, it constitutes a determining factor in the flexibility of the system, [ES] En esta contribución se presenta un algoritmo híbrido genéticoprogramación no lineal para el diseño óptimo de redes presurizadas de riego operando a turnos, y se implementa un indicador para evaluar la flexibilidad de los diseños resultantes del algoritmo híbrido. El objetivo principal es la minimización del costo económico de la red de tuberías y la evaluación de la flexibilidad de los diseños del sistema. La investigación considera como variables de decisión la asignación de turnos a las tomas de riego (hidrantes) y el dimensionado de las conducciones para reducir los costos de implementación. Con los resultados de la optimización se analiza la flexibilidad de la red hidráulica con base en la reasignación aleatoria de turno a los hidrantes, que simula las modificaciones susceptibles de ocurrir durante la explotación de la red. Para validar el algoritmo, una vez calibrado, éste fue aplicado al diseño de cuatro sectores de riego reales de Ecuador y España. Los resultados indican que los diseños obtenidos mejoran en costo y flexibilidad respecto a los encontrados con el algoritmo tradicional de la serie económica, y que la asignación de los turnos es de suma importancia para minimizar los costos de inversión en tuberías, lo que a la vez constituye un factor determinante en la flexibilidad del sistema

[ES] Un problema que preocupa a los gestores de los sistemas de drenaje es el incremento de eventos de lluvias extremas que cada vez se manifiestan con mayor frecuencia en diferentes lugares del mundo. Su ocurrencia produce sobrecarga hidráulica en el sistema de drenaje y en consecuencia inundaciones. Adaptar la infraestructura existente para que pueda soportar lluvias extremas sin generar consecuencias para sus habitantes se ha convertido en una necesidad para las ciudades. Este documento muestra una nueva forma de rehabilitar los sistemas de drenaje, utilizando para este objetivo una novedosa metodología que considera la inclusión de elementos de control hidráulico en la red, la instalación de tanques de tormenta en línea y la sustitución de tuberías. El análisis hidráulico de la red se realiza mediante el modelo Storm Water Management Model (SWMM) y para el proceso de optimización se usa con un algoritmo genético llamado Algoritmo Pseudo Genético. La inclusión de controles hidráulicos en la rehabilitación de redes de drenaje puede ser una alternativa para mejorar los niveles de inundación y a minimizar el tamaño de las estructuras de protección necesarias.

[EN] Proper design of a pumping system requires that the pump curve have to be as close as possible the system set-point curve, so that the energy used is optimal. This is achieved by control systems, in which and the combination between Fixed Speed Drives (FSD) pumps and Variable Speed Drive (VSD) pumps and the type of control to be used (flow or pressure) are involved. The objective of this work is to determine the optimal number of FSD and VSD pumps operating for each flow rate range. For this, a generic formulation is developed that allows discussing the influence of the network curve and the best efficient point of the pump provided in the pumping design solution analyzed. Additionally, the method includes analyses investment costs and maintenance costs and value the importance of these aspects in a design of a pumping system. The application of the methodology to different cases studies allows to conclude that the number of FSD and VSD pumps cannot be deduced in simple way as it is done in classic design of control system pump, but it requires a depth analysis in control modes system for do a proper pumping system design., [ES] Para un diseño adecuado de sistemas de bombeo se requiere que la curva motriz de una bomba opere lo más cerca posible a la curva consigna según varíe la demanda, a fin de que la energía utilizada sea la óptima. Esto se puede conseguir mediante sistemas de regulación, en donde interviene la combinación de operación de bombas de velocidad fija (BVF) y/o bombas de velocidad variable (BVV) y el sistema de control a utilizar (manométrico y/o caudalimétrico). El objetivo de este trabajo es determinar el número óptimo de BVF y BVV en funcionamiento para cada rango de caudal. Para la metodología propuesta se ha creado una formulación en forma adimensional para determinar la influencia de los parámetros de la curva consigna y la bomba en los sistemas de regulación, donde cada parámetro estará relacionado con los puntos nominales de la bomba. Adicionalmente, este trabajo incluye un análisis de la influencia del rendimiento de los conversores de frecuencia en los sistemas de regulación y la desviación que puede sufrir la eficiencia real del sistema de bombeo con respecto a la aplicación de las leyes de semejanza. La metodología propuesta se ha aplicado a distintos casos de estudio. De los resultados obtenidos, se ha podido concluir que el número de BVF y BVV no se puede inferir simplemente como en un diseño clásico de regulación. Incluso en algunos casos utilizar más número de bombas que el mínimo requerido de mejores resultados en términos de energía consumida. En general, se requiere un análisis profundo en los modos de regulación para determinar el número óptimo de bombas en funcionamiento.

[EN] Water temperature is often monitored at water sources and treatment works; however, there is limited monitoring of the water temperature in the drinking water distribution system (DWDS), despite a known impact on physical, chemical and microbial reactions which impact water quality. A key parameter influencing drinking water temperature is soil temperature, which is influenced by the urban heat island effects. This paper provides critique and comprehensive summary of the current knowledge, policies and challenges regarding drinking water temperature research and presents the findings from a survey of international stakeholders. Knowledge gaps as well as challenges and opportunities for monitoring and research are identified. The conclusion of the study is that temperature in the DWDS is an emerging concern in various countries regardless of the water source and treatment, climate conditions, or network characteristics such as topology, pipe material or diameter. More research is needed, especially to determine (i) the effect of higher temperatures, (ii) a legislative limit on temperature and (iii) measures to comply with this limit.

[EN] The Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) of the United Nations mentions that extreme rainfalls might increase their intensity and frequency in most mid-latitude locations and tropical regions by the end of this century, as a consequence of the rise of the average global surface temperature. Human action has given way to global warming which manifests with an increase in extreme rainfall. If these climatic conditions are added to the waterproofing that cities have been experiencing as a result of urban development, a scenario of growing concern for the managers of drainage systems is generated. The objective of drainage networks is preventing the accumulation of rainwater on the surface. Under the new conditions of climate change, these need to be modified and adapted to provide cities with the security they demand. The following article describes a method for flood control by using a rehabilitation model that connects the Storm Water Management Model (SWMM) 5 model with a genetic algorithm to find the best solutions to the flood problem. The final analysis is performed using the Pareto efficiency criteria. The innovation of this method is the inclusion of a local head loss in the drainage network, allowing the upstream flow to be retained by decreasing the downstream concentration time. These elements called hydraulic controls improve system performance and are installed in the initial part of some pipes coming out of storm tanks. As a case study, the developed method has been applied in a section of the drainage network of the city of Bogotá.

[EN] Proper design of a pumping system requires the use of a pump curve and set-point curve system. Both have to be as close as possible to optimize energy use. This is achieved by control systems in which the type of control (flow or pressure) and the combination between fixed speed drive (FSD) pumps and variable speed drive (VSD) pumps are involved. The objective of this work is to determine the optimal number of FSD and VSD pumps for each flow rate range in order to discuss the classic design of pumping stations and their control systems. For this, a methodology is applied that defines the parametric form of the pump curve, efficiency curve, and set-point curve in relation to the most efficient point. In this way, dimensionless expressions are obtained and the influence of the set-point parameters on the design of the control system can be analyzed. Additionally, the method includes an expression that estimates the performance of the frequency inverter, which is based on the load and pump speed rotation. The application of the methodology to different case studies allows us to question many classic procedures for pumping stations. In summary, it can be concluded that the appropriate number of variable speed pumps for each control system cannot be established in advance but requires an in-depth study of different available options.

[EN] Drainage networks are civil constructions which do not generally attract the attention of decision-makers. However, they are of crucial importance for cities; this can be seen when a city faces floods resulting in extensive and expensive damage. The increase of rain intensity due to climate change may cause deficiencies in drainage networks built for certain defined flows which are incapable of coping with sudden increases, leading to floods. This problem can be solved using different strategies; one is the adaptation of the network through rehabilitation. A way to adapt the traditional network approach consists of substituting some pipes for others with greater diameters. More recently, the installation of storm tanks makes it possible to temporarily store excess water. Either of these solutions can be expensive, and an economic analysis must be done. Recent studies have related flooding with damage costs. In this work, a novel solution combining both approaches (pipes and tanks) is studied. A multi-objective optimization algorithm based on the NSGA-II is proposed for the rehabilitation of urban drainage networks through the substitution of pipes and the installation of storage tanks. Installation costs will be o set by damage costs associated with flooding. As a result, a set of optimal solutions that can be implemented based on the objectives to be achieved by municipalities or decisions makers. The methodology is finally applied to a real network located in the city of Bogotá, Colombia.

[EN] The drainage networks of our cities are currently experiencing a growing increase in runoff flows, caused mainly by the waterproofing of the soil and the effects of climate change. Consequently, networks originally designed correctly must endure floods with frequencies much higher than those considered in the design phase. The solution of such a problem is to improve the network. There are several ways to rehabilitate a network: conduit substitution as a former method or current methods such as storm tank installation or combined use of conduit substitution and storm tank installation. To find an optimal solution, deterministic or heuristic optimization methods are used. In this paper, a methodology for the rehabilitation of these drainage networks based on the combined use of the installation of storm tanks and the substitution of some conduits of the system is presented. For this, a cost-optimization method and a pseudo-genetic heuristic algorithm, whose efficiency has been validated in other fields, are applied. The Storm Water Management Model (SWMM) model for hydraulic analysis of drainage and sanitation networks is used. The methodology has been applied to a sector of the drainage network of the city of Bogota in Colombia, showing how the combined use of storm tanks and conduits leads to lower cost rehabilitation solutions.

[EN] The drainage network always needs to adapt to environmental and climatic conditions to provide best quality services. Rehabilitation combining pipes substitution and storm tanks installation appears to be a good solution to overcome this problem. Unfortunately, the calculation time of such a rehabilitation scenario is too elevated for single-objective and multi-objective optimization. In this study, a methodology composed by search space reduction methodology whose purpose is to decrease the number of decision variables of the problem to solve and a multiobjective optimization whose purpose is to optimize the rehabilitation process and represent Pareto fronts as the result of urban drainage networks optimization is proposed. A comparison between different model results for multi-objective optimization is made. To obtain these results, Storm Water Management Model (SWMM) is first connected to a Pseudo Genetic Algorithm (PGA) for the search space reduction and then to a Non-Dominated Sorting Genetic Algorithm II (NSGA-II) for multi-objective optimization. Pareto fronts are designed for investment costs instead of flood damage costs. The methodology is applied to a real network in the city of Medellin in Colombia. The results show that search space reduction methodology provides models with a considerably reduced number of decision variables. The multi-objective optimization shows that the models¿ results used after the search space reduction obtain better outcomes than in the complete model in terms of calculation time and optimality of the solutions.

[EN] The analysis of transient flow is necessary to design adequate protection systems that support the oscillations of pressure produced in the operation of motor elements and regulation. Air valves are generally used in pressurized water pipes to manage the air inside them. Under certain circumstances, they can be used as an indirect control mechanism of the hydraulic transient. Unfortunately, one of the major limitations is the reliability of information provided by manufacturers and vendors, which is why experimental trials are usually used to characterize such devices. The realization of these tests is not simple since they require an enormous volume of previously stored air to be used in such experiments. Additionally, the costs are expensive. Consequently, it is necessary to develop models that represent the behaviour of these devices. Although computational fluid dynamics (CFD) techniques cannot completely replace measurements, the amount of experimentation and the overall cost can be reduced significantly. This work approaches the characterization of air valves using CFD techniques, including some experimental tests to calibrate and validate the results. A mesh convergence analysis was made. The results show how the CFD models are an efficient alternative to represent the behavior of air valves during the entry and exit of air to the system, implying a better knowledge of the system to improve it.

[EN] The cost of pumping is one of the most significant operational expenditures in a water distribution network. When a network has multiple water sources, which are associated with pumping stations, it may be possible to optimize those costs. One way to minimize costs is to determine the optimal flow rate for each pumping station and for every point of the temporal demand curve, while keeping the energy cost minimized. This also requires that the required minimum pressure at the critical point in the network be satisfied. This paper introduces a principle known as the setpoint curve as the key component of the network optimization methodology. A direct search algorithm based on the Hooke¿Jeeves approach is tested in two case studies. Two key cost factors, the electric tariff and the cost of water production, are considered for each water supply source. The model also considers the pressure-dependent consumption, which directly influences the setpoint curve. To test the methodology, a software application is implemented using the EPANET toolkit. The two case studies demonstrate the benefits of the approach in developing optimal pump operating policies which otherwise would be difficult to infer.

[EN] The problem presented in this edition of the Battle of the Water Networks is to define district metering areas (DMAs) in a large network. The problem is addressed in two phases. First, the complexity of the network is simplified by dividing it into three operational areas. Second, an optimization algorithm defines DMAs, looking for the best feasible solution. A preliminary simulation of the network is made. From this, engineering judgment allows for defining an initial set of elements suitable to change. In the second stage, a heuristic algorithm is used to search for the best DMA definition by selecting the locations and settings of the pressure-reducing valves and isolation valves. The network is then divided into two categories: the main pipes and the distribution pipes. Only the distribution pipes can be closed. With these restrictions and those described in the problem, the algorithm looks for the best DMA definition based on both the pressure and demand distribution among all the DMAs.

This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers, [EN] This paper presents a mathematical model for analyzing the emptying process in a pipeline using pressurized air. The rigid water column model (RWCM) is used to analyze the transient phenomena that occur during the emptying of the pipeline. The air-water interface is also computed in the proposed model. The proposed model is applied along a 271.6-m-long PVC-steel pipeline with a 232-mm internal diameter. The boundary conditions are given by a high-pressure air tank at the upstream end and a manual butterfly valve at the downstream end. The solution was carried out in a computer modeling program. The results show that comparisons between both the computed and measured water flow oscillations and gauge pressures are very similar; hence, the model can effectively simulate the transient flow in this system. In addition, the results indicate that the proposed model can predict both the water flow and gauge pressure better than previous models.

[EN] The growing urban development of population centers in much of the world joined with the significant effects of climate change are causing an increasingly important and recurring increase of the damage caused by flooding. Much of the drainage networks of cities were designed for precipitation characteristics and return periods that have proved to be insufficient with the lapse of time. Therefore, solutions need to be addressed both to reduce runoff generated flows as to control circulating ones through the rainwater drainage networks. All these flow control rain technologies are commonly known as SUDS (Sustainable Urban Drainage), term that encompasses a multitude of solutions to control runoff although many of them require significant costs that make them practically unviable. Therefore, not only should focus on reducing runoff input to the network but also in the flow control techniques development. The idea is to design strategies to reduce flow rain peaks and maximize the capacity of existing networks. The use of detention and storm tanks for flood control is a solution increasingly used as an alternative one to control increased rainfall caused by climate change [1]. Nature and execution of storm tanks can be very diverse, from conventional way based on concrete structures to the most innovative ones in which modular structures are employed to improve the construction speed if many modular units are required at the same time that minimizing urban supply disruption is achieved. Currently, a wide range of modular structures exists on the market with both, different geometries and sizes. In this study the Aquacell brand supplied by Mexichem-PAVCO in Colombia shown in Fig. 1 has been chosen for the development of this study.

[EN] The optimal sizing in water distribution networks (WDN) is of great interest because it allows the selection of alternative economical solutions that ensure design requirements at nodes (demands and pressure) and at lines (velocities). Among all the available design methodologies, this work analyzes those based on evolutionary algorithms (EAs). EAs are a combination of deterministic and random approaches, and the performance of the algorithm depends on the searching process. Each EA features specific parameters, and a proper calibration helps to reduce the randomness factor and improves the effectiveness of the search for minima. More specifically, the only common parameter to all techniques is the initial size of the random population (P). It is well known that population size should be large enough to guarantee the diversity of solutions and must grow with the number of decision variables. However, the larger the population size, the slower the convergence process. This work attempts to determine the population size that yields better solutions in less time. In order to get that, the work applies a method based on the concept of efficiency (E) of an algorithm. This efficiency relates the quality of the obtained solution with the computational effort that every EA requires to find the final design solution. This ratio E also represents an objective indicator to compare the performance of different algorithms applied to WDN optimization. The proposed methodology is applied to the pipe-sizing problem of three medium-sized benchmark networks, such as Hanoi, New York Tunnel and GoYang networks. Thus, from the currently available algorithms, this work includes evolutionary methodologies based on a Pseudo-Genetic Algorithm (PGA), Particle Swarm Optimization (PSO) and Harmony Search (HS). First, the different algorithm parameters for each network are calibrated. The values used for every EA are those that have been calculated in previous works. Secondly, specific par

[EN] One of the most important concerns within the field of urban hydraulic engineers is the right management of water resources. When there is more than one water source, there is a question that must be answered: How much water should be provided by each water source according to the demand curve of the network? This work proposes a methodology that solves this question. It involves an energy analysis of the water network based on the concept of the setpoint curve. The setpoint curve gives, for every supplied flow, the minimum head needed to satisfy pressure requirements in the network. In this sense, the setpoint curve of every source relates two variables: supplied flow and minimum required head. Energy consumption in every source is evaluated by means of the product of these two variables. Then flow distribution among sources is optimized and minimum heads are obtained from the setpoint curve. The optimization process has been validated in two different ways. On one hand, a discrete method has been used, where a predefined combination of flow distributions are evaluated. On the other hand, the solution is found by means of Hooke-Jeeves and Nelder-Mead optimization algorithms. To apply these methods EPANET and its Toolkit has been applied to the mathematical model of the network. The optimization process can be applied to networks models with and without leakages. Finally, the methodology is applied to two cases, one academic network and real network where maximum flow limitations of every source were also taken into account.

[EN] A mathematical model is a powerful tool for simulating different scenarios that occur in a water distribution network without making physical experimentation. According to the objectives, a model can be classified into three categories: layout, design and operation. Furthermore, the level of detail is strongly related to the objective that the model tries to achieve. However, bigger amount of information does not mean better accuracy. For example, a fully detailed mathematical model of the network would lead to know every single connection. Usually, this information is so difficult to compile as imprecise. Therefore, one of the most important stages in elaborating a model consists of the model simplification, also known as skeletonization. During the works made for model skeletonization some assumptions are made. Most of the times, these assumptions may produce significant errors. Among the different techniques for network skeletonization, series pipe removal is one of the most used. It consists of replacing several adjacent pipes with a single one which must present the same head losses than the pipes being substituted. When there are no intermediate consumptions the problem has been effectively solved. The problem arises when a demand appears in one of the pipes being removed. It has been demonstrated that methods which assume constant roughness coefficients (either Hazen-Williams or Darcy equations) produce errors in the head losses. These errors may be even higher if travel time is included as a restriction, for example in water quality models. This paper reviews the most common techniques for serial pipes association. The error will be evaluated in both hydraulic and quality models. Finally, a method for exact substitution of serial pipes with intermediate demands is proposed. This method imposes two restrictions (head losses and travel time) and gives exact results when the flow direction is known. The method is tested with an example that highlights the

[EN] Hydraulic models of water supply networks are widely used by utility companies to assist in decision making. The reliability of the model strongly depends on the quality of its calibration, that is, the correspondence between the measure variables and the calculated ones. When dealing the model is static, the calibration is easy to reach for average values of the variables. On the contrary, dynamic models need to spatially allocate demands and distribute them among the nodes of the network, which complicate the problem. The paper proposes a methodology for preliminary calibration of hydraulic models based on advanced calibration techniques. This methodology is applied to models with both pressure-dependent and independent demands. Pressure-dependent demands are related to leakages and are spatially distributed according to the length of the pipes and volumetric efficiency of the district metering area (DMA) being considered. In order to model leakages, the Germanopoulos model has been chosen. Thus, leakage flow is a function of the length of the pipes and the pressure along them. The equation to quantify the volume of leakage is a modification of the orifice equation. From this leakage model, a calibration process is proposed. It consists in three steps. First, a global leakage coefficient is calculated in order to satisfy daily mass balance of produced unaccounted and consumed water. In the second step, a time demand pattern is calculated. After these two steps a preliminary model is obtained. Finally, a conventional calibration process is done using discrepancies between pressure measurements and model result to adjust both roughness and minor losses coefficients. In order to validate this calibration methodology, a case study was used in Guayaquil (Ecuador) in which three DMA were studied. The results showed that the method converges very quickly and is effective regardless the volumetric efficiency of the network.

[EN] One of the main concerns in many cities is the need to rehabilitate or expand their drainage systems. Increasing rainfall intensities related with climate change, uncontrolled growth and excessive waterproofing of cities causes that original drainage networks design have became insufficient. Inadequate drainage networks make necessary to develop rehabilitation models of existing networks. This models should be compatible with them. This paper presents an optimization methodology to generate different solutions for the existing network improvement. This methodology uses as starting point a model of the actual storm water network. In this paper the SWMM model is used to perform the hydraulic analysis of the network. Also a Pseudo-Genetic Algorithm (PGA) is used as optimization engine. This PGA model has been previously developed for other hydraulic optimization problems. The developed optimization model includes as decision variables: the rehabilitation or replacement of existing pipes, the potential location of stormwater retention tanks at certain points and their size, the initial state of the existing pumping units, and the start and stop levels of each pump. To evaluate each solution during the optimization process it has been necessary to develop a series of costs functions: a) a cost function or damage function relating the flood level and associated damage costs; b) a cost function of stormwater retention tanks which relates the investment cost in the construction of the tank with its volume; c) a pipeline rehabilitation cost function that relates the cost of rehabilitation or replacement of a pipe with its nominal diameter; d) a cost function for each pump unit giving the cost of the electrical energy consumed during the operation. Finally, the methodology developed has been applied to solve the flooding problems of a small section of the drainage network of the city of Bogota (Colombia).

[EN] One of the challenges arising from the implementation of the European Higher Education Area is the search for new methods of evaluation and learning. This paper proposes a new project-based learning initiative and a competitive evaluation system in the student's knowledge related to the analysis and planning of water distribution networks. The methodology is based on the development of a team work project to improve an existing water supply network. Based on computer simulations and acquired learning, students must find the best solution for system operation. Finally, the works (presented and exposed) are evaluated in a competitive way, giving the highest score to the best solution according to previously established criteria. This initiative has been implemented in the subject "Analysis and modeling of water distribution networks" that is taught in the Master in Hydraulic Engineering and Environment of the UPV. The initial results show a better perception of the subject by the students and a certain improvement in their academic results, [ES] Uno de retos derivados de la puesta en marcha del Espacio Europeo de Educación Superior es la búsqueda de nuevos métodos de evaluación y aprendizaje. En este trabajo se plantea una nueva iniciativa de aprendizaje basada en proyectos y en una evaluación competitiva de los alumnos en sus conocimientos relacionados con el análisis y planificación de las redes de distribución de agua. La metodología se basa en el desarrollo en grupo de un proyecto de mejora de una red de abastecimiento existente. A partir de simulaciones computacionales y de los conocimientos adquiridos los alumnos deben encontrar la mejor solución de funcionamiento del sistema. Finalmente los trabajos presentados y expuestos son valorados de forma competitiva otorgando la máxima puntuación a la mejor solución de acuerdo a unos criterios previamente establecidos. Esta iniciativa ha sido implementada en la asignatura "Análisis y modelación de redes de distribución de agua" que se imparte en el Máster en Ingeniería Hidráulica y Medio Ambiente de la UPV. Los resultados iniciales muestran una mejor percepción de la asignatura por parte de los alumnos y una cierta mejora en los resultados académicos de los mismos.

[EN] EPANET is probably the most widespread model for water distribution network (WDN). More than twenty years after its appearance, it has become a global reference both for hydraulic and quality analysis of water networks. In 2000, EPANET 2 appears, which includes as most important computational feature a new Toolkit. This toolkit was a library of functions allowing the modification of network data and reading results without access to the appropriate files. Over time, the use of this library has been the communication protocol for every application developers who use the method propose by Todini and Pilati to analyze the behavior of WDN. This library also provides interface tools that allow the execution of a simulation from an external application, as long as the network characteristics had been previously defined. This paper presents a change in the original EPANET model, including a new menu in the graphical user interface (GUI). This menu allows users to set up a personal collection of Add-In tools, which use both project data and simulation results. These tools can be customized and allows to extend the analysis capability of EPANET. All of them can access EPANET functions through the Toolkit and were developed by the authors during the Spanish translation of EPANET, taking into account the homologous Add-in tools developed for SWMM model. As an example of the operation and capabilities of this new menu, several applications integrated as EPANET add-in tools are presented. These tools perform tasks such as importing data network from both CAD and GIS systems, the design of WDNs using genetic algorithms, automatic assignment of initial water quality to network nodes; the skeletonization of a network or optimization of pumping schedule in the network in order to achieve a minimum energy cost.