Coupled Human and Water Infrastructure Systems Sector Interdependencies: Framework Evaluating the Impact of Cities Experiencing Urban Decline

Abstract

Water, wastewater, and stormwater infrastructure systems are intrinsically interdependent, impacting the performance and operations of each individual infrastructure. The demands placed on and revenues generated for these infrastructures are impacted by human interactions, such as price elasticity and population dynamics. The consequences of these human–infrastructure interactions may be seen in shrinking cities, where chronic population decline has led to underfunded and underutilized infrastructures. This paper evaluates human-water and wastewater systems sector interdependencies in shrinking cities to explore water demand, utility revenues, public support, and payoff periods for retooling alternatives. To assess the dynamic behavior of the water sector systems, a hybrid framework is used that incorporates agent-based and system dynamics modeling. Driving the approach is data gathered from published and publicly available literature, two case studies, and a survey deployed to residents of 21 U.S. shrinking cities. This study quantifies the endogenous, physical interdependencies and the exogenous, complex human interactions. The epistemic uncertainty associated with human–infrastructure interactions is explored by incorporating stochastic parameters rather than the traditional deterministic parameters. Furthermore, the framework enables the assessment of interdependencies with parameters tailored to a city’s unique characteristics.