Valve control has been widely used for reducing pressure and leakage in water distribution systems. However, the optimized conditions often change the water flow paths and increase residence times, thus turning pressure control and water quality into conflicting objectives. The current paper aims at the development and discussion of a new methodology for the simultaneous optimization of water age and pressure in distribution systems by valve operation. The methodology is applied to a full-scale case study considering several optimization scenarios. Results show that significant improvements in both water age and pressure are achieved when these parameters are jointly optimized, whereas optimizing only pressure leads to a significant increase in water age. Additionally, the joint optimization of water age and pressure can be achieved without compromising pressure-required levels. The proposed methodology can be easily applied to any water distribution network, improving system performance with minor interventions in the networks.

A novel comprehensive resilience assessment framework for drinking water systems is proposed integrating different resilience perspectives (i.e., robustness, autonomy, flexibility, reliability, preparedness and recovery), oriented by objectives, criteria and metrics, applicable at the tactical level. The resilience assessment framework is applied to a Portuguese real water distribution network, enabling the evaluation of the system’s resilience. The infrastructure dimension is the main contributor to the low resilience results, particularly in terms of infrastructural robustness, as the infrastructure has exceeded the average service life and has low rehabilitation rates. In terms of autonomy, the system highly depends on external water and energy sources. Regarding the service dimension, most of the drinking water available is used for non-potable uses (e.g., irrigation), without alternative sources. The detailed diagnosis identified network area R6 as the priority area. Assets rehabilitation, increasing storage capacity, finding alternative water and energy sources, and minimizing non-potable uses are relevant improvement measures that promote the reinforcement of the system’s resilience. The resilience assessment framework is a very useful tool for the daily and tactical management of drinking water systems.

This paper presents and demonstrates a novel scenario-building methodology that integrates contextual and future time uncertainty into the performance assessment of water distribution networks (WDNs). A three-step approach is proposed: (i) System context analysis, identifying the main key factors that impact the WDN performance; (ii) Scenario definition, identifying the implicated WDN variables, describing its possible evolution, and conjugating them to further establish the reference scenario and the two most relevant and opposite ones; and (iii) Scenario modelling, simulating the WDN behaviour for those scenarios. The obtained spatial and temporal hydraulic results are further used to calculate performance metrics. The methodology is applied to a real WDN to assess resilience performance considering infrastructure asset robustness (real water loss performance indicator), service reliability (minimum pressure index), and service flexibility (network resilience index). A new formulation to assess the metric evolution over time is proposed, deducting the further-away performance results by using an uncertainty weight. The results demonstrate that the increase in metric amplitude for the opposite scenarios over time highlights future uncertainty, reflecting context uncertainty, and the comparison of metric spatial distribution (i.e., at the pipe/node levels) highlights critical areas with higher associated uncertainty.

Os reservatórios de água para consumo humano permitem garantir reservas de água nos sistemas de abastecimento e gerir variações do consumo. Contudo, a sua configuração e os modos de operação podem ter implicações na qualidade da água distribuída. Este trabalho apresenta uma caracterização dos reservatórios de água em Portugal, incidindo nas características físicas e operacionais que condicionam o seu desempenho do ponto de vista da mistura e renovação da água. Foi pela primeira vez avaliada a mistura da água nos reservatórios portugueses, pela determinação das frações de volumes de renovação necessárias para garantir a mistura da água que entra em cada ciclo de enchimento com a já existente. Os resultados mostram que a mistura é garantida em cerca de 74% das células circulares e que a variação de nível necessária para tal num ciclo de enchimento é, em média, de 51%.

Performance assessment is essential for effectively managing drinking water systems. It allows to understand the system's behaviour, identify critical components and subsystems, and help with the decision analysis of measures to improve economic, infrastructural and water and energy resources. The current paper proposes an updated methodology for diagnosing drinking water networks, considering different perspectives: water and energy efficiency, infrastructural sustainability, and the quality of service provided, including resilience and redundancy concepts. Several performance indicators and indexes, including Resilience index and Entropy, are recommended to describe each perspective. The methodology is applied to a real-life network, and the attained results are discussed. The status quo situation for the network area is assessed, and the main problems are identified (i.e., high friction losses, inefficient pump operation, old pump equipment). Different improvement solutions are considered (e.g., pipe replacement with higher diameter, pump operation improvement, pump replacement). These interventions are considered individually or combined. Using the resilience-based perspective with other performance assessment criteria has provided a broader assessment. The resilience index has proven sensitive to the different alternatives, endorsing the system's efficiency. Smaller values of the resilience index indicate that a small amount of energy in excess is available as surplus energy in the consumption nodes, being dissipated, either as pumping inefficiencies, water losses, or friction and singular head losses. The Entropy metric is sensitive to the network layout and is helpful in alternatives that consider flow path alterations to prevent the impact of pipe failure. The best improvement alternative achieves a considerable enhancement in energy efficiency, maintains a good quality of service, improves the system's infrastructural sustainability, and corresponds to the highest resilience index value.