Complex Adaptive System Framework to Simulate Adaptations of Human-Environmental Systems to Climate Change and Urbanization: The Verde River Basin

Water management in the arid western United States must address imminent increases in freshwater withdraws due to population growth and climate change. Stresses in the water supply system can be addressed through demand management, which restricts water uses or instates bans, incentivizes toilet retrofits or landscape conversions, and encourages conservation through outreach and education. These policies rely on the behaviors, compliance, and conservation of residential and agricultural users. This research develops a complex adaptive system (CAS) framework to analyze the dynamic interactions between changing water demands and limited water resources for population growth, land use conversion, and climate change scenarios. Water supply and demand for the arid Verde River Basin is explored through an agent-based model (ABM). Three types of agents are encoded, including policy makers (utility managers/planners) and agricultural and residential water users. Agents are initialized with business-as-usual behaviors, a set of signals, demand-reduction actions, and supply-augmentation actions. ABMs are coupled with water infrastructure models, which are in turn forced with hydro-climate and water demand projections to capture the feedbacks and simulate policy and consumer-level agents' roles in promoting balance between water demands and supplies. To determine the dynamics of societal responses to hydro-climatic extremes and the likelihood of water system adaptations to environmental change in the future, this research explores data about sociopolitical responses and actions by analyzing existing policies and management strategies. By synthesizing these data, a timeline of events and estimates for the relative probability of actions being taken are generated and used to encode policy-maker agents. The ABM framework provides important insights into the dynamic interaction of sociotechnical variables by simulating potential feedbacks of human-environmental and hydro-ecological systems that arise from adaptations to climate change and growth. Insight gained through this simulation study can be used to guide policy making under changing hydro-climatic scenarios over a long-term planning horizon.