Outburst floods play a significant role in shaping landscapes, impacting societies, and influencing the Earth system. The year 2023 marked the centennial anniversary of J Harlen Bretz’s first publication on “the Spokane Flood” in the Channeled Scabland, which kickstarted research on outburst flood science and set off a decades-long debate on the role of catastrophic floods in landscape evolution. Since then, the field has expanded from its origins in eastern Washington to sites across the globe and on other planets, covering myriad aspects of outburst flood processes and effects.

The Penrose Conference marked the centennial by examining the past century of outburst flood science and looking ahead to the next 100 years of research. Conference sessions were organized around four themes: 1) the Channeled Scabland and the Missoula floods; 2) outburst floods as a universal process, grouped by geographic region: North and South America; Eurasia; and Mars and other planets); 3) mechanics of outburst flood processes; and 4) broader implications of outburst floods, including modern hazards, landscape evolution, and Earth system impacts. The week produced inspiring discussions on the history of outburst flood science, presented the state-of-the-art in the field, and identified research gaps and future directions. Equally importantly, it fostered collaborations among the international outburst flood community and facilitated knowledge exchange with residents of this incredible landscape, including members of the Confederated Tribes of the Colville Reservation, the National Park Service, and Washington State Parks.

The conference took place at Camp Delany, a rustic retreat center within Sun Lakes-Dry Falls Washington State Park near Coulee City, WA. Camp Delany lies within the plunge pool of the Grand Coulee cataract complex, which was carved by the Missoula floods and provided a stunning setting for discussing outburst flood science. The conference included 70 participants from institutions in 16 countries on four continents, as well as three members of the Confederated Tribes of the Colville Reservation, on whose traditional lands much of the Channeled Scabland sits. Of the participants, 31 percent identified as female, 17 percent as graduate students, and 21 percent as early career researchers (<10 years post-PhD completion). The conference emphasized student and early career researcher participation by giving extended oral presentation times to students and early career attendees and by pairing students and early career scientists with more senior scientists to encourage one-on-one discussions on research and professional development.

Several key themes emerged during the week. First, despite the great diversity of outburst flood science—spanning geographic regions, planets, methods, and time periods—many researchers grapple with the same underlying questions. What is the role of outburst floods in landscape evolution, and how do landscapes recover post-flood? How scalable is a single flood event to different landscapes, time periods, or triggering mechanisms? How can we most effectively integrate numerical models and field studies? What new methods or approaches are needed to address remaining knowledge gaps?

The two field trips illustrated many of these themes. Though focused on the Missoula Floods in the Channeled Scabland, field trip stops provoked discussions on other flood landscapes across the solar system, as well as paleoflood reconstruction challenges, flood erosional mechanics, sediment transport, and tracing floodwater sources.

Another key theme was the importance of tackling research questions with an interdisciplinary, multi-method approach. Presentations described linking onshore and offshore records to reconstruct flood impacts on ocean circulation and climate; combining different geochronological techniques to date paleofloods; and linking remote sensing, field observations and modeling results. They also demonstrated the lessons that can be learned from other study sites—for example, recognizing similar depositional sequences from floods on different continents; comparing erosional features on Earth and Mars; or adapting early warning systems to different flood basins.

Overall, this Penrose conference affirmed that the future is bright for the next century of outburst flood science. The field continues to expand in new geographic, thematic, and methodological directions, and it involves an increasingly diverse group of scientists from across the globe who strive for effective collaboration and communication. Despite a century of study, the Channeled Scabland—like other outburst flood landscapes—still holds fascinating unanswered questions for all who explore it.

Last Modified: 03/22/2024
Modified by: Isaac J Larsen