Consequence management of chemical intrusion in water distribution networks under inexact scenarios

Abstract

The US Environmental Protection Agency (EPA)'s Response Protocol Toolbox provides a list of recommendations on actions that may be taken to minimize the potential threats to public health following a contamination threat. This protocol comprises three steps: (1) detection of contaminant presence, (2) source identification and (3) consequence management. This paper intends to explore consequence management under source uncertainty, applying Minimize Maximum Regret (MMR) and Minimize Total Regret (MTR) approaches. An ant colony optimization algorithm is coupled with the EPANET network solver for structuring the MMR and MTR models to present a robust method for consequence management by selecting the best combination of hydrants and valves for isolation and contamination flushing out of the system. The proposed models are applied to network number 3 of EPANET to present its effectiveness and capabilities in developing effective consequence management strategies. Key words | ant colony algorithm, consequence management, minimize maximum regret, water network contamination NOTATION G k à gb objective function value for the ant with the best performance within the past total iterations L set of options {l ij } α, β parameters which control the relative importance of the pheromone trail against heuristic value η ij heuristic value representing the desirability of state transition ij ρ coefficient of pheromone evaporation τ ij (t) total pheromone deposited on path ij at iteration t k à gb ant with the best performance within the past total iterations P ij (k, t) likelihood that ant k selects option l ij for decision point i at iteration t q random variable uniformly distributed over [0, 1] q 0 tunable parameter ∈[0, 1]

Understanding the Changes in Global Crop Yields Through Changes in Climate and Technology

“…Consequence management of future climate‐driven factors that adversely affect crop yields can be optimized (Afshar & Najafi, ) and highlighted by understanding the relationships between crop yields and climate patterns. This will enable us to evaluate alternative food policy strategies and taking precautionary economic measures.…”

Contamination event diagnosis in drinking water networks: A review

“…Therefore, simulation-optimization models are used to evaluate the effectiveness of the strategies for emergency response events. A suitable intervention strategy is calculated using single or multiple objectives, using computational intelligence methods, including evolutionary computation (Afshar & Najafi, 2014;Hu et al, 2020b;Fasaee et al, 2020;Qiu et al, 2021;Hu et al, 2022).…”

“…Different impact metrics used in the literature include: Minimization of the number of contaminated nodes, using a function that defines whether a node is contaminated or not based on a threshold applied to the contaminant concentration, or minimization of the total contaminant concentration at nodes (Afshar & Najafi, 2014;Bashi-Azghadi et al, 2017;Moghaddam et al, 2020); Minimization of the number of exposed individuals, using a function that calculates the number of people affected at a node based on the population at the node (Zechman, 2013;Moghaddam et al, 2022); Minimization of the volume of contaminated water consumed, using a function of the demand when the concentration at a node is above a threshold (Preis & Ostfeld, 2008b;Guidorzi et al, 2009;Bashi-Azghadi et al, 2017;? ); Maximization of the flushed contamination mass by the hydrant set, using a function that calculates the contaminant mass that exits the network from hydrant flushing locations (Fasaee et al, 2020).…”

Socio-Hydrology: A New Understanding to Unite or a New Science to Divide?

“…Water resources systems analysis involves normative and positive approaches, develops simulation and optimization models, and uses quantitative and qualitative approaches [116][117][118][119]. Water resources systems studies do not always have economics as a component (e.g., [85,[120][121][122][123][124][125][126][127][128][129][130][131][132][133][134][135][136]) and are not always focused on designing and running water infrastructure (e.g., [31,82,130,[137][138][139][140][141][142][143][144][145][146][147][148]). Additionally, the water resources systems studies do not always limit themselves to proposing solutions as Di Baldassare et al [13] argue.…”