Collaborative Research: Climatic and geologic controls on the threshold conditions for bedrock single- and multi-thread channels

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Rivers carve valleys, transport nutrients and sediment, and create habitat in mountainous regions. Of particular importance in mountain regions are bedrock rivers, whose banks and bed are solid rock rather than gravel or sand. Bedrock rivers can be contained to a single channel or can branch into multiple channels known as braided or anastomosing. Whether the river has one or multiple channels impacts the hillslope-to-floodplain-to-river connection that is crucial to nutrient transfer and habitat. The goal of this project is to understand why bedrock rivers form one or multiple channels based on the climate and tectonic conditions. The research will help understand where bedrock rivers have greater potential for habitat and can inform conservation efforts in mountain rivers. The project will introduce high performance computing to a small undergraduate college through mentored research and will support outreach to Colorado K-5th grade schools through a flooding and erosion hazards activity.This research tests the climatic, lithologic, and rock uplift conditions that lead to single-thread bedrock channel stability through the development of a new numerical model that explicitly considers variable channel width during meandering. The numerical model is calibrated using cosmogenic radionuclide and optically stimulated luminescence derived rates of channel migration and erosion in the Smith River, Oregon, as well as a global dataset of bedrock channel conditions. Expected results will distinguish the geologic and climatic conditions suitable for rich habitat development and nutrient/sediment connectivity, and help scientists understand the past conditions encoded in bedrock rivers and their terraces. The developed model will be publicly shared through the NSF-supported Community Surface Dynamics Modeling System (CSDMS).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.