SEDIMENT PRODUCTION AND TRANSPORT PROCESSES IN AN ARCTIC WATERSHED UNDERGOING CLIMATE CHANGE

Arctic landscapes are among the most vulnerable on Earth to climate change, largely due to the rapid degradation of permafrost. In steeper bedrock-dominated terrains, warming permafrost can lead to increased rock damage and sediment production due to enhanced temperature conditions for frost-driven cracking events. This cold weather rock stress, combined with summertime diurnal temperature swings, set the stage for progressive rock failure. This provides detached sediment for rockfalls, which can amplify the delivery of sediment to channels by debris flow and fluvial processes. However, there is a fundamental lack of data on current rates of sediment production and transport in Arctic watersheds, making it impossible to predict the transient responses and rates of periglacial processes under future climate change. To begin to address this gap, we are conducting a multi-year field-based study of the Black Mountain catchment in the Aklavik Range (Canada). This site was chosen due to the presence of an alluvial fan at the base of the catchment, providing a closed system where we can consider how changing temperatures influence physical weathering and transport. Recent work has focused on documenting sediment transport conditions on the fan, yielding modern-day fluvial and mass flow transport rates. Surficial and sedimentological mapping suggests that accelerated warming has increased sediment supply due to frost cracking, leading to fan aggradation and increased debris flow activity. Current work is focused on estimating sediment production rates as a function of modern climate using a pre-existing physically based frost cracking model.