Estimating risk of contaminant intrusion in water distribution networks using Dempster–Shafer theory of evidence

Abstract

Intrusion of contaminants into water distribution networks requires the simultaneous presence of three elements: contamination source, pathway and driving force. The existence of each of these elements provides ‘partial’ evidence (typically incomplete and non-specific) to the occurrence of contaminant intrusion into distribution networks. Evidential reasoning, also called Dempster–Shafer theory, has proved useful to incorporate both aleatory and epistemic uncertainties in the inference mechanism. The application of evidential reasoning to assess risk of contaminant intrusion is demonstrated with the help of an example of a single pipe. The proposed approach can be extended to full-scale water distribution networks to establish risk-contours of contaminant intrusion. Risk-contours using GIS may help utilities to identify sensitive locations in the water distribution network and prioritize control and preventive strategies.

Keywords:

• Contaminant intrusion
• Water distribution networks
• Evidence theory
• Dempster–Shafer theory
• Risk
• GIS
• Simplex plot
• Uncertainty

Acknowledgements

This article presents the results of a preliminary investigation of an ongoing research project, which is co-sponsored by the American Water Works Association Research Foundation (AwwaRF) and National Research Council (NRC) of Canada.