Urban water-supply systems consist of both physical infrastructure and policies that govern their use. These systems are designed to be adaptable to a wide range of supply and demand conditions. However, climatic and social shifts are placing new stresses on water-supply systems that require substantial changes, also called transitions, to maintain system performance. This research analyzes transitions across 12 large-scale urban water systems in the United States to achieve two goals: 1) to better document the interactions among various environmental and human factors that may prompt transition, and 2) to identify which infrastructure and policy design choices can foster practical transitions to increase sustainability. To accomplish these goals this project will gather and analyze long-term human and environmental data to synthesize relationships and trends, and develop two complementary models to identify pathways that can lead to a sustainable water-supply transition. This project will directly involve stakeholders in multiple stages of the research to both learn from their experiences and ensure that outputs meet their needs. This project also will provide education and training opportunities to help students develop the competencies needed to collaborate across fields, a skill that is essential to tackle current environmental challenges.

The proposed research utilizes a "convergence" approach to investigate how integrated urban water systems can be managed effectively as they face increasing pressures from climate change, population growth, and other environmental factors. This research will involve a longitudinal analysis of system stressors, an examination of hydrological detection and change, construction of a Bayesian model to forecast the probability of stressors exceeding thresholds for transition, and development of a dynamic model to identify promising design choices. This project will benefit urban water-supply systems in four ways by: 1) combining institutional analysis with dynamic modeling to gain new insights into the role of institutions in shaping system dynamics; 2) linking the detection and attribution of hydrological change to watershed and policy processes, which will result in new knowledge about the drivers and the impacts of hydrological change; 3) synthesizing quantitative and qualitative data, stakeholder knowledge, and inductive and deductive modeling approaches to enhance system performance; 4) identifying how specific infrastructure and institutional design choices affect system resilience and transition probability. Knowledge relating design to outcomes is key because, although cities cannot control the dynamics of hydrological or human systems, they can alter design choices. Examining urban water transitions can also offer general insights for other socio-environmental challenges where preemptive intervention will be beneficial.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.