SFM-DERIVED MODERN POST-FIRE EROSION MAGNITUDES COMPARED TO HOLOCENE EROSION RATES IN A STEEP, 1KM^2 IDAHO CATCHMENT

As climate change alters wildfire frequency and severity, it becomes vital to better understand the processes and impacts of post-fire erosion. Post-fire erosion occurs rapidly via multiple processes and often under low-recurrence interval precipitation events in steep mountain drainages; debris flows are well-documented and the most dramatic. However, partitioning the total erosion by distinct process in rugged, burned catchments has been difficult thus far, including spatially, volumetrically, and temporally. Here, we determine the spatial domains and volumetric contributions of distinct erosion processes by applying drone-based Structure from Motion photogrammetry to derive cm-scale topographic surveys. We combine the ultra high resolution topographic datasets with traditional field work in a high-relief, unnamed 1km^2 catchment burned in the 2016 Pioneer Fire in central Idaho which produced a debris flow. We partition the total eroded volume into channelized debris flow scour, hillslope rilling, and other diffusive processes with various approaches. Additionally, we use radiocarbon dating to compare the modern post-fire erosion yields to Holocene rates at the same site, and to other erosion rate figures from the region.