A Complex Adaptive Systems Approach to Simulate Urban Water Resources Sustainability

Urban growth impacts the sustainability of water resources due to conversion of natural to impervious cover and increased withdraws for human consumption. These processes increase runoff, change the timing of in-stream flows and storage, and deplete available water resources. The quality and availability of urban water resources, therefore, is the aggregated result of land- and water-use choices of citizens in a municipality. For example, land owners define the amount of imperviousness in lots through the adoption of Low Impact Development (LID), and consumers choose water conservation techniques and practices. Consumer decision-making is a dynamic process, however, as it is driven by water resources policies, which is, in turn, based on the current quality and availability of water resources. This research simulates a watershed as a Complex Adaptive System (CAS), which is characterized by interacting actors who influence and are influenced by the environment and the choices of other actors through dynamic feedback processes. A CAS can be simulated through the use of Agent Based Models (ABMs), which represents the interaction of multiple actors within an environment. A CAS framework is developed for an illustrative case study to simulate landowners and households as ABMs, coupled with a hydrologic and reservoir model. Agents make decisions to choose land use types, implement LID, and adopt water conservation practices. The CAS framework presents a more comprehensive view of the urban water system and the dynamic interactions between stormwater management and water supply for facilitating the water resources planning process.