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- Lessons learnt from the application of MCDA sorting methods to pipe network rehabilitation prioritizationPublication . Caetano, João; Carriço, Nelson; Covas, DídiaMost water distribution networks were built a few decades ago, showing symptoms of deterioration. Additionally, current renewal rates are insufficient to overcome pipe networks’ continuous ageing process. The development of methodologies for assisting the definition of pipe rehabilitation, including which pipes, and when and what financial amounts to allocate to this activity, are of the utmost importance. These methodologies typically have to attend to several points of view, for which multicriteria decision analysis (MCDA) techniques may be used. The current paper demonstrates and discusses the application of two MCDA techniques—the ELECTRE TRI-C and FlowSort—to a real water distribution network. Both techniques allowed assigning every single pipe to a predefined priority category, although the ELECTRE TRI-C proved to be more effective. These approaches imply that the planning of investment needs is carried out based on individual pipes, but these approaches are not consistent with the actual rehabilitation projects. A clustering technique called affinity propagation, together with cost functions, were applied to define and quantify homogeneous rehabilitation units. Even so, the methodology did not prove to be rigorous enough for the selection of pipes to be rehabilitated. On the other hand, it proved effective to estimate annual budgets for rehabilitation.
- Tension chord model para cargas alternadasPublication . Lourenço, Miguel; Ferreira, Miguel; Oliveira, Cristina; Almeida, JoãoO Tension Chord Model (TCM) é um modelo de análise para simular o comportamento de um elemento de betão armado, considerando, individualmente, as relações constitutivas de ensaios uniaxiais dos materiais aço e betão, e, com o comportamento conjunto simulado através de uma lei de aderência rígido-plástica simplificada. Neste artigo, o TCM é estendido para situações de cargas alternadas e repetidas, apresentando-se comparações entre resultados experimentais e numéricos, de modo a contribuir para que sejam gradualmente utilizados modelos de comportamento físicamente consistentes no estudo de elementos de betão armado.
- Literature review on earthen vernacular heritage: contributions to a referential frameworkPublication . Gilberto, Carlos; Ribeiro, Telma; Achenza, Maddalena; Oliveira, Cristina; Varum, HumbertoThe state of the art of earthen architecture and vernacular built heritage comprises a complex set of issues that range from fundamental problematic recognition to anthropological and cultural studies and, more recently, to technological and experimental analyses. This paper addresses the development of the field, following the milestones of the international literature and pursuing a reflective-theory approach within a historical framework. It aims to explore the main contributions that have enhanced vernacular heritage and earthen architecture as specific domains, from pioneering public awareness essays to institutional expertise guidelines. Finally, in addition to the literature review process, this paper considers the recent corpus of recommendations from conservation management reference institutions, the updating of the operative problematic of earthen vernacular built heritage, and the relevance of local community involvement in facing increasing challenges.
- Multi-criteria decision analysis in urban water asset managementPublication . Carriço, Nelson; Covas, Dídia; Almeida, Maria do CéuThis paper presents a multi-criteria decision support methodology for selection and prioritization of rehabilitation intervention in urban water infrastructures considering performance, cost and risk and a long-term perspective. This methodology is divided into three main stages: problem identification, structuring and evaluation. Problem structuring, a crucial stage for the outcomes, includes identifying objectives, selecting scenarios within the analysis period, defining problem options and the problematic type. Problem evaluation includes the selection of assessment metrics, selection of the aggregation method, application of the method and sensitivity and robustness analysis and final recommendations. The methodology is applied to a real case study of a water distribution system, being the different stages presented in detail and obtained results discussed.
- Método multicritério aplicado ao planeamento de reabilitação em redes de distribuição de águaPublication . Caetano, João; Carriço, Nelson; Covas, DídiaO presente artigo tem como objetivo a aplicação de um método multicritério de apoio à decisão a um caso de estudo para a definição de condutas candidatas a intervenção de reabilitação. Para tal, escolheu-se o ELECTRE TRI-B, da família dos métodos ELimination Et Choix Traduisant la REalité (ELECTRE), dado que permite uma razoável flexibilidade na priorização de investimentos em reabilitação, comportando desvios, face às disponibilidades financeiras e planos orçamentais, e atendendo a distintos critérios e métricas de avaliação. O caso de estudo permitiu identificar as dificuldades encontradas na aplicação deste método, sendo realizadas considerações relativas ao estabelecimento dos parâmetros estruturais do método e à análise das preferências dos decisores, sendo estes aspetos críticos e condicionantes para os resultados finais. Outra constatação importante é o impacto da escassez ou inexistência de informação organizada e disponível, que impossibilita o estabelecimento de métricas abrangentes. O desenvolvimento de uma metodologia generalista de apoio à decisão com base no método ELECTRE TRI-B é um processo complexo.
- Multi-objective optimization of pressure sensor location for burst detection and network calibrationPublication . Ferreira, Bruno; Antunes, André; Carriço, Nelson; Covas, DídiaThis paper proposes a methodology to determine the optimal location of pressure sensors for the simul- taneous calibration of the hydraulic network model and the detection of pipe bursts. The methodology considers a search space reduction process and aims at maximizing nodal pressure sensitivities to both pipe roughness coefficients and pipe burst sizes. A multi-objective optimization problem is formulated for a given number of sensors and multiple optimal configurations of pressure sensors are obtained. Three different optimal configurations are selected and compared: one solution that individually maximizes each objective function (two solutions) and one trade-off solution. The methodology is applied to a real water distribution network with hourly consumption data. Results demonstrate that (i) the optimal loca- tion of pressure sensors hardly changes with the perturbation values used to numerically compute the sensitivities and (ii) minor differences can be found in the performance of pipe roughness calibration and pipe burst location by using either a solution that individually maximizes each objective function or the trade-off solution considering the high number of pressure sensors (26) and the oversized pipe diameters to comply with firefighting conditions, being pressure less sensitive to friction and flow rate changes.
- Computational Tools for Supporting the Operation and Management of Water Distribution Systems towards Digital TransformationPublication . Carriço, Nelson; Ferreira, Bruno; Antunes, André; Caetano, João; Covas, DídiaThis paper presents a set of computational tools specially developed for supporting the operation and management of water distribution systems towards digital transformation of water services. These tools were developed in the scope of two R&D projects carried out in Portugal, DECIdE and WISDom, during 2018–2022. The DECIdE project focused on the development of tools for importing cadastral and operational data, as well as on the three operational tools for supporting the performance assessment: the first allows the calculation of different key performance indicators, both at a global and sectorial level, which is an annual requirement of the water regulator, and the other two allow the calculation of the water and the energy balances and a set of complementary indices. The WISDom project aimed at the implementation of applications that directly address specific water utility needs, namely, the flow rate data processing, the optimal location of pressure sensors, the identification of critical areas in the distribution network for pipe burst location, and the prioritization of pipes for rehabilitation. Implemented tools are useful to support water utilities in the daily operation and management of their systems, being a step forward towards digital transformation of the water sector.
- Rehabilitation of an industrial water main using multicriteria decision analysisPublication . Carriço, Nelson; Covas, Dídia; Almeida, Maria do CéuThis paper demonstrates the application of multicriteria decision analysis (MCDA) method- ology in a real case study aiming to choose the best rehabilitation intervention of an industrial water main. This methodology is composed of three main stages: problem identification, structuring, and evaluation. Problem structuring, a crucial stage for the outcomes, includes identifying objec- tives, selecting scenarios within the analysis period, defining problem alternatives, and defining the problematic type. Problem evaluation includes the selection of assessment metrics, selection of the aggregation method, application of the method, and a sensitivity and robustness analysis. Two scenarios, nine assessment metrics, and seven alternatives are established, and two ranking methods (the additive model and ELECTRE III method) are used to compare the alternatives. The results show that the best solution corresponds to building a new pipe and deactivating the existing one, as it significantly reduces the pipe failure risk and O&M costs, whereas the worst solution is always the status quo case, since it is the only alternative that does not improve the system performance, independently of the ranking method and the analyzed scenario
- Optimal number of pressure sensors for real-time monitoring of distribution networks by using the hypervolume indicatorPublication . Ferreira, Bruno; Carriço, Nelson; Covas, DídiaThis article proposes a novel methodology to determine the optimal number of pressure sensors for the real-time monitoring of water distribution networks based on a quality hypervolume indicator. The proposed methodology solves the optimization problem for different numbers of pressure sensors, assesses the gain of installing each set of sensors by means of the hypervolume indicator and determines the optimal number of sensors by the variation of the hypervolume indicator. The methodology was applied to a real case study. Several robustness analyses were carried out. The results demonstrate that the methodology is hardly influenced by the method parameters and that a reasonable estimation of the optimal number of sensors can be easily achieved.
- Flowrate time series processing in engineering tools for water distribution networksPublication . Ferreira, Bruno; Carriço, Nelson; Barreira, Raquel; Dias, Tiago; Covas, DídiaThe current paper presents a comprehensive methodology for processing unevenly (and evenly) spaced flowrate time series for subsequent use in engineering tools, such as the calibration of hydraulic models or the detection and location of leaks and bursts. The methodology is a four-step procedure: (a) anomaly identification and removal, (b) short-duration gap reconstruction, (c) time step normalization, and (d) long- duration gap reconstruction. The time step normalization is carried out by a numerical procedure prior to the reconstruction process. This reconstruction process uses a pattern model coupled with regression techniques (i.e., autoregressive integrated moving average and exponential smoothing). The methodology is calibrated using Monte Carlo simulations applied to a water utility flowrate time series and validated with two additional time series from different water utilities. Obtained results demonstrate that the proposed methodology can process flowrate time series from water supply systems with different characteristics (e.g., consumption pattern, data acquisition system, transmission settings) both for normal operating conditions and during the occurrence of abnormal events (e.g., pipe bursts). This methodology is a very useful tool for the daily management of water utilities, preparing the time series to be used in different engineering tools, namely, hydraulic simulation, model calibration or online burst detectio
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