Dynamic Model of the Evolution of an Epidemic Down an Urbanized River System

The evolution of water-borne diseases involves the dynamics of two interconnected systems: the water-distribution network and the human population. Whereas a number of mathematical models have been developed for each of these systems, little has been done to integrate them into a unified framework. In the present study, such a framework is developed in order to simulate the progression of an epidemic down an urbanized river system. An epidemic model is used to simulate the temporal progression of infection in a series of cities that draw their drinking water from an adjacent river. Along with the number of infected individuals, the epidemic model also computes the quantity of pathogens in each city's wastewater. The wastewater time series for each city then serves as input to a river model which simulates the transport and fate of the pathogens down to the next city's drinking-water intake. Along with hydraulics, the model accounts for bacterial die-off due to factors such as solar radiation and water temperature. Thus, the framework provides a means to assess the integrated progression of the disease as it moves down the system. In particular, the impact of a number of factors (e.g., intercity distance, urban population size, water temperatures, light attenuation, etc.) will be explored. The talk concludes with a discussion of the implications that such model building offers for adaptive and preventative strategies.