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Pressure control is recognized as an efficient measure for reducing leaks from water distribution systems. We have evaluated the effectiveness of various pressure control modes by means of pilot-operated diaphragm type pressure-reducing valves (PRVs), taking into account the sensitivity of the valves to various settings. First, the response of a PRV to consecutive pressure settings variations was experimentally evaluated in the hydraulic simulation laboratory of National Institute for Scientific Research. These experiments revealed that the studied valve only reacts when variation in the pressure setting corresponds to at least a 1/6 turn of the pilot valve. Second, an actual case study from Quebec City, Canada, was simulated to evaluate the impact of the PRV response on three pressure control modes: fixed control, time-based control, and real-time control (RTC). The results show that RTC of pressure leads to reductions in leakage rate for the studied network but that the PRV operational constraints limit the expected performance of RTC. Key words: hydraulic simulation laboratory, leakage reduction, pressure settings, real time control, time based control, valve sensitivity. Le controle de la pression est reconnu comme une mesure efficace pour reduire les fuites des reseaux de distribution d'eau. L'efficacite de divers modes de regulation de la pression, au moyen de vannes de regulation de la pression (VRP) a diaphragme a commande pilote, est evaluee dans le present document en tenant compte de la sensibilite de la vanne a divers reglages. Tout d'abord, la reponse d'une VRP a des variations de pression consecutives a ete evaluee experimentalement dans le laboratoire de simulation hydraulique de l'Institut national de la recherche scientifique. Ces experiences ont revele que la vanne etudiee ne reagit que lorsque la variation du reglage de la pression correspond a au moins 1/6 de tour de la vanne pilote. Deuxiemement, une veritable etude de cas de la ville de Quebec, au Canada, a ete simulee afin d'evaluer l'impact de la reponse de la VRP sur trois modes de controle de pression : le controle fixe, le controle base sur le temps et le controle en temps reel (CTR). Les resultats montrent que le CTR de la pression entraine une reduction du taux de fuite sur le reseau etudie, mais que les contraintes operationnelles de la VRP limitent le rendement attendu du CTR. [Traduit par la Redaction] Mots-cles : laboratoire de simulation hydraulique, reduction des fuites, reglages de pression, controle en temps reel (CTR), controle base sur le temps, sensibilite des vannes., Introduction The managers of water distribution systems (WDSs) have adopted a variety of strategies in recent years to ensure efficient management of WDSs, particularly for reducing water loss, energy savings, [...]

Combined sewer overflow (CSO) control strategies are commonly selected relying on optimization or multicriteria analysis. A methodology is proposed in this paper for selecting and evaluating the solutions to mitigate stormwater problems in combined sewer systems (CSSs) based on the understanding and rigorous diagnosis of the causes of the observed problems using hydrological/hydraulic simulations. The methodology was applied to a sewer catchment near Montreal (Canada) in order to reduce the magnitude and recurrence of sewer surcharge and local flooding without increasing the recurrence of CSOs. Two types of control strategies were considered: (1) large-scale solutions, i.e., redirection of stormwater inflows and separation of the CSS; and (2) source control solutions including both green and gray infrastructure. These solutions were evaluated through a comparative analysis of nine scenarios. Based on the results, source control solutions could be considered as the most effective interventions on the studied catchment for eliminating or significantly reducing the occurrence of sewer surcharge (from an average of 6.7 to 2.6) and surface flooding on local streets (from an average of 3.5 to 0.4 per year). The developed methodology is a valuable tool to be applied to other urban drainage catchments that encounter problems similar to those observed on the studied catchment. [ABSTRACT FROM AUTHOR]

Robert Schertzer and Eric Taylor Woods' book analyses tweets posted by Donald Trump, Marine Le Pen and Brexit supporters in 2017 from a historical perspective in order to reveal the deep roots of white ethnic nationalism. This commentary questions the explanatory nature of the analysis, and highlights how the book inadvertently contributes to the ongoing naturalisation of nationalism, particularly in Western countries. [ABSTRACT FROM AUTHOR]

Optimization of the spatial distribution of green infrastructures (GIs) was performed for a combined sewer system located in the Province of Quebec, Canada, using a simulation-optimization tool with the aim of reducing seasonal combined sewer overflows (CSOs). The performance of four CSOs control alternatives involving the individual and integrated implementation of GIs with storage tanks and real time control (RTC) of the sewer was evaluated for a nine-year simulation period of historical rainfall data and for 20%-increased rainfall data (representative of potential climate change impact). The integration of GIs with RTC of the sewer (with or without storage tanks) lowered the total CSO volume by 95% to 99% under historical rainfall data and by 93% to 96% under increased rainfall intensities when compared to the reference scenario. Adapting GI's number and location for optimal CSO control rather than according to space availability criteria reduced CSO frequency but had only a slight impact on CSO volume reduction. [ABSTRACT FROM AUTHOR]

Existing methods used to identify the important factors that can improve predicting structural deterioration of sewer pipes rarely take into account the interactions and correlations among them. Here we present a standardized method that combines use of the Cox model and likelihood ratio test, and overcomes these limitations of previously employed methods. This combined method is applied to the pipes of two Canadian sewer systems, and its results are compared to the results of two simpler methods for the identification of the factors that significantly influence sewer pipe deterioration. The three methods identified pipe age as the principal factor driving the structural deterioration of sewer pipes. However, slight differences between the methods for other potential influential factors (material, slope, and diameter) showed that accounting for the interactions and correlations among factors, as is possible with the proposed method, is crucial to identifying the factors having a significant impact on pipe deterioration. Key words: covariates, Cox model, Kruskal-Wallis, likelihood ratio, structural state, survival analysis. Les methodes existantes permettant d'identifier les facteurs d'influence qui doivent etre pris en compte dans la modelisation de la deterioration structurale des conduites d'egout prennent rarement en compte les interactions et/ou les correlations entre ces facteurs. Une methode standardisee, basee sur l'utilisation combinee du modele de Cox et du test du rapport de vraisemblance, est proposee dans cet article. Cette methode est appliquee aux conduites de deux reseaux d'egout canadiens et ses resultats sont compares aux resultats de deux methodes plus simples pour l'identification des principaux facteurs influents. Les trois methodes identifient l'age des conduites comme etant le principal facteur d'influence dans le processus de deterioration des conduites. Cependant, de legeres differences entre les resultats de ces methodes concernant certains facteurs potentiellement influents (materiau, pente et diametre) demontrent que la prise en compte des interactions et des correlations entre les facteurs, rendue possible avec la methode proposee, est cruciale pour identifier les facteurs ayant un impact significatif. Mots-cles: covariables, modele de Cox, Kruskal-Wallis, rapport de vraisemblance, etat structural, analyse de survie., 1. Introduction Many mathematical models exist to predict the structural condition of sewer pipes over time, depending on several variables. These models can be classified into three groups (Ana and [...]