Chilkat Valley geohazard observatory

https://www.nsf.gov/awardsearch/showAward?AWD_ID=2052972&HistoricalAwards=false A roughly 5-mile long segment of the Haines Highway near the village of Klukwan (Chilkat Indian Village) is home to two large debris fans (Klukwan and Mile 19) each of which have experienced numerous debris flows annually in recent years (Figure 1). This is one of the most expensive highways in the state of Alaska and historic debris flow activity has damaged or destroyed Native Alaskan villages and on-going activity threatens the village of Klukwan and other residents as well as the critical Haines Hwy lifeline that connects residents to Haines and Canada (Figure 2). Establishing an experimental facility in this area provides a unique opportunity to 1) respond to critical community needs related to resilient housing, 2) advance fundamental science, 3) develop workforce and training for Alaska Native students, and 4) strengthen partnerships with CIV that originated with a recent NSF CoPe project. Scientific motivation: High-latitude landscapes like this site in SE Alaska is experiencing profound changes due to climate change, including permafrost degradation and increased storm frequency and intensity, that increases the probability of triggering land surface hazards. Despite their proximity, the source catchments for the Klukwan and M19 fans have dramatically different lithology (Figure 3), which imparts a profound control on sediment production mechanisms and grain size, which serve as first-order controls on key processes that constitute the hazard cascade. In addition, landslide volume is the primary control on the mobility (and thus hazard potential) of rock avalanches and debris flows, which necessitates characterization of the processes that contribute to landslide material via initiation and entrainment. In addition, debris fans are constructed by the accumulation (and erosion) of debris flow deposits via channel migration and avulsion and the details of how these depositional landforms evolve is paramount to hazard and risk management. Some fundamental science questions that could be addressed by investing resources in this area include: What conditions and storm events are associated with recent and future failures? What processes and properties control the rate, spatial pattern, and caliber of bedrock extrication that produces the material for debris flow initiation and entrainment? What controls debris flow entrainment and deposition and thus flow volume? How do recent debris flows and fan geometry influence the potential for avulsion? How does grain size influence debris flow behavior, avulsions, dam/outburst events, and potential damage to humans and infrastructure? As part of this project, which also includes cameras and infrasound sensors, we plan to deploy short-period seismometers on each of our two study catchments to document the signature of debris flow and rockfall activity.