Scenario Planning: Embracing the Potential for Extreme Events in the Colorado River Basin.

Scenario planning (SP) has been increasingly utilized by water managers and planners in the 21st century as climate and other uncertainties have challenged traditional planning approaches. This paper discusses the potential for scenario planning processes in the Colorado River Basin in the southwestern United States to build collective understanding of compound and cascading risks, and to identify possible solutions at multiple scales. Under the Colorado River Conversations Project, we convened a series of conferences and scenario planning workshops over the past 3 years to explore the potential to enhance the use of social and physical sciences in river management, and to broaden the community of people and entities engaged in discussions about managing the Colorado River. Working with a group of thirty water managers and other interested parties representing all 7 basin states, several Tribes, NGO's and Mexico, we used a participatory, mixed-methods approach to scenario planning that identified multiple drivers of change and developed eight science-based storylines from the intersection of these drivers. The development of the storylines and the subsequent conversations with participants about impacts and solutions resulted in a framework for understanding low probability-high consequence climate and other risks across the Colorado River Basin. We highlight three lessons that speak to the value and role of SP for fostering collaboration and creativity. These lessons include: (1) the importance of process in SP in fostering deliberate community building across sectors and geographies; (2) identifying challenges with engaging with uncertainty, complexity, and risk; and (3) determining what these findings mean for future SP in the Colorado River Basin and beyond.