River impacting landslides in the Fraser Canyon

Hillslope mass wasting can have an outsized impact on both long-term landscape evolution and short-term hazards. Inputs of coarse sediment can shield river beds, alter local flow hydraulics, and impede fish passage. This talk focuses on the Fraser Canyon in British Columbia, a 375 km reach of the Fraser River where the 2018 Big Bar Landslide temporarily blocked the river and created a hydraulic barrier to salmon migration. I will examine the history of landsliding in the Fraser Canyon, evaluate hillslope morphology and valley connectivity to identify areas susceptible to future river-impacting landslides, and explore how mass wasting influences local river hydraulics within the canyon. These case studies indicate that boundary conditions at the upstream end of river networks affect downstream hillslopes, prompting questions of how drainage divide migration, incision into underlying bedrock, and valley widening impact landslide activity.