Agent-Based Modeling for Simulating the Effects of Demand Reduction on Urban Water Resources and Infrastructure Systems

Incorporating alternative water sources, such as rainwater harvesting and reclaimed water, within a municipal water supply system can lead to reduced demands on freshwater supplies and allow urban water systems to continue supplying and expanding water services. Implementation of large-scale alternative water source projects is, however, hindered by limited experience and knowledge regarding the integration of alternative water sources into existing conventional water supply systems. The large-scale introduction of alternative water sources into a water supply system is a complex socio-technical process that involves transitions in consumer water use culture, the underlying engineering infrastructure, and urban water management. Consumers play a central role in the transition process, as their adoption of alternate water sources drives the success of demand-side management strategies. Existing modeling and analysis methods are limited in their abilities to simulate the complex and adaptive behavior of consumers as they adopt alternative water sources; the effects of interconnections and interactions between social and technical components; and resulting system dynamics. An integrated water management approach is developed to assess the impacts of the transition on existing water systems and coordinate plans for new infrastructure while maintaining existing levels of service.;Dynamic modeling approaches, including agent-based modeling (ABM) and cellular automata (CA) approaches are used to represent consumers, and simulate coupled human engineering systems. An initial modeling framework that simulates the evolution of water availability and system performance in a water system as homeowners adopt lot-level rainwater harvesting is developed. An ABM of consumers is coupled with water supply and distribution system models. The modeling framework is applied to a case study and demonstrates how an ABM framework can simulate the transition of water infrastructure performance and water resources availability based on homeowner water use behavior.;Subsequent work focuses on reclaimed water as an alternative water source. Social factors play an important role in consumer perception and attitudes towards the use of reclaimed water, and theory from the social sciences are used for model development. A modeling framework using a CA approach is developed to simulate consumer adoption of reclaimed water. The model is developed using diffusion of innovations theory, and simulates a diffusion process driven by the neighborhood effect. The CA model of consumers is coupled with distribution system models of the potable and reclaimed water networks and is applied for the Town of Cary, North Carolina. The model simulates the co-evolution of emergent distribution system hydraulics in the dual water system as consumers adopt reclaimed water.;Risk and benefit perceptions also play an important role in the adoption on new technologies. An ABM framework, based on the concept of "risk publics", is developed to simulate reclaimed water adoption. The risk publics ABM is an empirical-based approach that uses the concepts of belief clusters, defined on the basis of shared risk and benefits perceptions, to explain the adoption of new technology. This research develops and demonstrates the risk publics model to simulate emergent community opinion dynamics and consumer adoption of reclaimed water based on interpersonal communications. The risk publics ABM is applied to the Cary case study. Adoption projections are compared to those obtained using the CA model, providing insight on the influence of alternative social mechanisms on consumer adoption of reclaimed water. Using the risk publics model, projections of consumer adoption within Cary are developed for alternative infrastructure expansion plans. These results explore the potential impacts of management decisions, in terms of infrastructure improvement schedules, on consumer adoption of reclaimed water.