Agent-based modeling to simulate demand management strategies for shared groundwater resources

Growing population centers in the arid southwest increase the demand for water, which is typically met through increased groundwater withdrawals. Hydro-climatic extremes due to climate change may also increase demands and decrease the replenishment of groundwater supply. Groundwater aquifers typically cross watershed, municipal, and management boundaries, and as a result, multiple diverse agencies manage a shared resource. Municipalities and management districts define individual demand management strategies that adapt water consumption to falling groundwater levels. The interactions among governing agencies, consumers, and the environment influence the performance of local management strategies and the availability of regional groundwater resources. This research develops an agent-based modeling (ABM) framework to analyze the dynamic interactions among changing water demands and limited groundwater resources under the stresses of population growth and climate change scenarios. Households are initialized as agents with properties and attributes to define indoor water use, outdoor water use, and water use reduction. Policy-maker agents are encoded to represent governing agencies that mandate or encourage water use restrictions. Demand management strategies are simulated as the response of a policy-maker agent to groundwater levels, safe yield, and climate variables. The framework is applied for municipalities located in the Verde River Basin, Arizona that withdraw groundwater from the Verde Formation-Basin Fill-Carbonate aquifer system. The effects of management strategies on water savings and basin-wide groundwater levels are explored, based on water use demands and reductions in different sectors of municipal water use. Insights gained through this simulation study can be used to guide groundwater policy-making under changing hydro-climatic scenarios for a long-term planning horizon.