CAREER: Balancing Local and Systemic Resilience in the Western Water Network

Arizona State University, Scottsdale AZ

Investigators

Abstract

This Faculty Early Career Development (CAREER) grant will model a large component of the western regional water system to help facilitate planning for resilient water supply and usage at both local and regional levels. The construction of reservoirs, aqueducts, and pump systems has transformed the hydrological landscape of the American west. These feats of engineering have facilitated growth by moving water in space (via interbasin transfers and distribution infrastructure) and in time (by storing water during wet periods for later use). Consequentially, once separate river basins are now networked via water transfers and shared demand centers, here termed the Western Water Network. The creation of a regional water supply network generated benefits as water can be moved across basins to meet demands and water users can mitigate drought impacts with a portfolio of supplies. However, this connectivity also introduces new risks. Just as links in financial systems can reduce the risks of local shocks while raising the risk the system instability, interconnected water supply systems have tradeoffs between local and systemic risks. These tradeoffs are primed to shift as climatic change, demand shifts, and a renegotiation of operating rules play out in the coming years. This project will use a set of models to assess the tradeoffs between local (e.g. municipal or state level) and systemic (e.g. basin wide) resilience under recent and current rule structures and explore modifications to reduce the risk of failure under plausible future conditions. New knowledge of these tradeoffs will allow the deliberate choice of benefits and risks when re-designing operating rules and infrastructure. As interconnected river basins are not unique to the America West, lessons from study of the Western Water Network may be applicable globally. This project addresses a gap in understanding the tradeoffs between local and system resilience in networked water systems, and the role of infrastructure and institutional design. New knowledge of these tradeoffs is particularly relevant now as water supply systems are highly optimized to tolerate observed historic variability but both social and climatic changes are pushing many water supply systems globally beyond these historic conditions. As such robust systems are often fragile beyond their range of previously experienced vulnerability, we need to prepare our infrastructure and institutional systems now for projected changes. Specifically, this project will: 1) develop statistical models of regional streamflow that account for both the spatial and temporal patterns critical to evaluating regional water systems under historic and projected conditions; 2) build and test a model of the test case Western Water Network that merges water systems modeling with an agent-based model capable of simulating routine operations and adaptive changes; 3) evaluate the system as currently operated under paleo-historic and projected streamflow conditions; and 4) assess the tradeoffs between local and systemic resilience under recent and current rule structures and explore modifications to reduce the fragility space under plausible future conditions. To implement this work, the team will collaborate with stakeholders to both learn from their tacit knowledge of the system and share results. In recognition of the multifaceted nature of infrastructure challenges facing the next generation on engineers, this project will also develop educational modules and techniques for guiding students through synthesis that are applicable within and outside the classroom. 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.