1336911 (Istanbulluoglu). Landslides disrupt aquatic habitats and damage infrastructure (e.g., roads, utilities, dams). Landslide hazards in the west are expected to grow with climate change, but to date, geologic landslide research has been typically conducted independently from hydroclimate research. There is need for unifying these two lines of research to provide regional scale landslide prediction for resource management and climate adaptation strategies. Washington Cascade Mountains experience landslides across a wide a range of climates, vegetation, and topography, and thus, work done here is relevant to mountain areas across the globe. Working with state and federal agency partners, this project team will develop a regional-scale distributed numerical model in conjunction with 50+ years of landslide observations across the Washington Cascades to answer the following research questions: 1) What are the relative roles of location (geology, topography, slope) vs. climate (precipitation, temperature, snowmelt, and recharge rates) on landslide frequencies? 2) How well does a new, transformative model combining the methods of geotechnology, geology, and hydroclimate prediction reproduce past spatial-temporal patterns and frequencies of landslides? Specifically, a) Are probabilistic or deterministic methods more reliable? and b) In which cases are finer, more site-specific data needed (e.g., snow pack on mountainsides providing extra load and a key trigger for landslides, or freeze-thaw cycles changing soil stability) for accurate model performance. 3) How will climate change likely impact landslide locations and frequencies? Specifically, a) What are the largest expected hazards (e.g., road wash-out, sediment flux, culvert failure)? and b) Under these predictions, what decision support tools are needed for sustainable management of landscapes and streams over complex terrain? While the effects of climate change on water resources and stream temperatures have been extensively studied using numerical models in recent decades, only limited studies focused on landslide sediment delivery. These studies either use empirical rainfall thresholds and geologic susceptibility maps at regional scales to identify landslides, or focus on detailed hydrology over several meters. The first method excludes essential physics, while the second cannot be used over large areas. This project will integrate these two lines of thought and potentially transform how regional landslide research is done. The proposed model will pioneer an innovative numerical model design by combining subsurface flow recharge and surface runoff from an 5,500-m resolution land surface model (VIC) with a 10-m resolution probabilistic slope stability model (SINMAP). The work is targetedto directly impact resource management and will be incorporated into K-12, undergraduate, and graduate education. The research plan has been developed in close collaboration with state and federal agencies, who will immediately put results to use in land management. A workshop will be conducted in year 3 of the project to give model training to resource managers and share our final modeling framework with them. In conjunction with education professionals, an education module will be developed for high school students. This module will be presented at select schools in Seattle through the University of Washington's "University in the Classroom project," wherein students receive university credit for high-level work. The findings of the project will contribute to undergraduate and graduate level teaching at the University of Washington.
