An approach to modelling and simulation of epidemics of diseases from pathogens spreading over water distribution systems

Abstract

The paper describes a method for construction and analysis of a combined simulation model of epidemics of diseases due to pathogens spreading over water distribution systems (WDS). The implemented model is composed of three main elements dealing with simulation of pathogen spreading over WDS, simulation of epidemics within an area inhabited by many (interconnected) populations and optimization tools for calibrating the values of parameters present in the models. The element related to modelling the pathogen spread over WDS is based on a widely used EPANET methodology for the analysis of hydraulics in water supply networks. The other element of our approach for epidemics simulation refers to a generalized model of epidemic based on the standard SIR model. Both these modelling and simulation tools are supported by optimization procedures for calibration. To this end we propose two different kinds of tools: the first is a version of a Gauss–Newton procedure for nonlinear least–squares problems; the second solves a multiobjective optimization problem with the help of evolutionary algorithms. We show, using the well–known Walkerton case, that relatively few empirical data points are needed to build epidemic model with good forecasting properties.