Hydroclimatic Extremes as Challenges for the Water Management Community: Lessons From Oroville Dam and Hurricane Harvey

Julie A. Vano, Michael D. Dettinger, Rob Cifelli, David Curtis, Alexis Dufor, Kathleen Miller, J. Rolf Olsen, and Anna Wilson

Record-breaking extreme storms in 2017 challenged communities as well as the power-, water-, and flood-management systems that served them; raising concerns over the impacts of climate change. We reviewed post-assessment and media reports and had conversations with water managers who worked to reduce risks and damages during these events. We noted issues water managers confronted during these events, and then identified a few lessons those experiences offered about framing attribution studies to serve management needs.

Key Findings:

• Assessing impacts of extreme weather events and finding attribution to climate change is difficult. The near-disaster at Oroville and the extraordinary flood damage in Houston cannot be strictly attributed to the meteorological extremes, but rather owed much to engineering (e.g., compromised spillways), policy (e.g. building in floodplains), and other non-meteorological challenges.
• Attribution studies are necessary to provide guidance to water managers in what to expect for changes in the number and frequency of atmospheric river events, future storm temperature impacts on seasonal snow/rain ratios, the persistence of drought periods, and how climate change will affect hydrologic design standards for critical infrastructure.

It is important to note that attribution studies should be careful about how results are expressed, because both meteorological and operational factors are important contributors to impacts realized from extreme events.

From our collective experience, we see potential for attribution studies to better inform water management decisions and enhance public safety to reduce impacts of extreme hazards. However, for studies to be actionable for water management, attention to those aspects of extremes that make them most challenging to management will be needed, requiring improved understanding and engagement with the water management community. We encourage future Explaining Extreme Events studies to take on this challenge.