Water Contamination Impact Evaluation and Source-Area Isolation Using Decision Trees

Abstract

The security of drinking water distribution operation is an important issue that has received increasing interest within the last few years. The U.S. EPA has issued guidelines for water utilities regarding which qualitative and quantitative metrics to monitor, and what response actions to take from the moment a contamination event alarm has been triggered, until the contamination has been accommodated and the system has returned to normal operation. Expanded sampling is a type of response action in which the water utilities examine water quality at certain locations in the network after a contamination event has been detected to help evaluate the contamination impact and locate the source-area. In this work, we propose a computational approach, based on decision trees, for choosing a sequence of nodes in the distribution network to perform expanded sampling, such that the water contamination impact is evaluated and the source-area is isolated, with as few manual quality samplings as possible. To illustrate the solution methodology, we present results based on a simplified and a benchmark water distribution system.