Contamination intentionnelle des réseaux d'alimentation en eau potable : de nouveaux indicateurs pour analyses de vulnérabilité, de sensibilité et de criticité

International audiencePerforming a comprehensive risk analysis is primordial to ensure a reliable and sustainable water supply. Though the general framework of risk analysis is well established, specific adaptation seems needed for systems such as water distribution networks (WDN). Understanding of vulnerabilities of WDN against deliberate contamination and consumers’ sensitivity against contaminated water use is very vital to inform decision-maker. This paper presents an innovative step-by-step methodology for developing comprehensive indicators to perform sensitivity, vulnerability and criticality analyses in case of absence of early warning system (EWS). The assessment and the aggregation of these indicators with specific fuzzy operators allow identifying the most critical points in a WDN. Intentional intrusion of contaminants at these points can potentially harm both the consumers as well as water infrastructure. The implementation of the developed methodology has been demonstrated through a case study of a French WDN unequipped with sensors

Analyse de risque, évaluation des impacts, perception – méthodologie. Deliverable 7.1&2 projet ANR/BMBF F/All SMaRT-OnlineWDN

The SMaRT-OnlineWDN research project aims at developing an online security management toolkit for drinking water distribution systems based on the combination of monitoring/modelling. In the frame of this research project four research goals are defined as 1) Online simulation model considering hydraulic state and water quality, 2) Optimal location of sensors based on the online simulation model, 3) Online source identification of contaminants and 4) Risk analysis, identification and evaluation of impacts (real impacts and perceived ones). The WP7 addresses this latter objective. The present documents presents the developed methodology for risk assessment and an approach to analyse the perception of consumers of drinking water quality and their mobilisation capacity to react in case of contamination. The current report is divided into 2 main parts. The first part details the risk analysis methodology developed within this project, fitting to the question of intentional contamination (chemical or biological) of a drinking water distribution network, based on one side on the characteristics steps of risk analysis (asset characterisation, threat characterization, vulnerability analysis; consequence analysis) and on the other side on the specificity of a water system build in a network structure and delivering a product used for alimentary devices either for consumers or for industrials. So intrusion and propagation analysis was made based on hydraulic simulation and transport model developed within this project to take into account the network specificity and its serviceability. Concerning water consumers and users, a typology has been build and sensitivity to contamination and consequences on both health and economic activity has been evaluated. Economic consequences on the utility are also taken into account. The risk analysis is achieved according to 4 levels of analysis: Consumers and water users sensitivity analysis Network vulnerability analysis Consequences identification and evaluation Risk assessment The methodology is characterised by the use of Fuzzy logic and multi-decision aggregation methods in the 4 levels. This methodology gives answers to the utility to define the best localisation of sensors in regard with the propagation area and the sensitivity of the consumers and also to adapt its policy for crisis management. The second part presents the methodology of a sociologic analysis, on water consumers, on the question of representation of drinking water: from perception on social mobilization. The study is based on 2 main concepts: The role of trust in the water and risk management and the concept of “alarm raisers”. The first issue is to identify if people do question the water quality in case of a sanitary problem. Secondly, if it is possible to identify potential responsible for population in such crisis and identify what kind of authority people alert? This work was driven after elaboration of a questionnaire and a 20 minutes call phoning interview. The data of the survey data issued from 200 successful calls within consumers of the 3 end users were analysed with Multiple Correspondence Analysis (MCA) and Hierarchical Ascendant Classification (HAC). The analysis achieved a characterisation with 2 axes: trust and involvement of the consumers. This document ends by a conclusion and perspectives of economic evaluation in the objective of cost benefit analysis of the online security management tool