Sociotechnical Simulation for Evaluating Adaptive Threat Response Actions for Water Distribution Contamination Events

Abstract

In the event that pathogens or toxins are introduced to a water distribution system, water utility managers should take the most effective actions to protect public health. As a contaminant propagates through the pipe network, a utility manager must select response actions based on available information, such as water quality sensing or complaints from consumers. Response plans are developed from a large set of options, including hydraulic responses that influence the mechanisms of system hydraulics and social responses that alter water consumption behaviors of the public through, for example, media broadcasts. The contaminant plume can shift from a previously expected direction due to public behaviors and altered system hydraulics during the event; in addition, new information will become available from water quality sensors and consumer complaints. Therefore, a manager should adapt to new conditions and information during the event to select the most effective responses. This research explores a new simulation framework to evaluate the efficiency of adaptive response rules for a water utility during a contamination event. A Complex Adaptive System (CAS)-based methodology is developed to couple the engineering model of a water distribution system with agent-based models of consumers and utility managers to simulate feedback among management decisions, system hydraulics, and the public behavior. A utility manager is represented as an agent, who responds to the event through a set of rules and equations, and consumers are represented as agents who update their water activities based on exposure to the contaminant and warnings from the utility agent. The proposed model is applied to an illustrative mid-sized virtual city to investigate the significance of interactions and identify sets of rules to effectively protect public health.