POSTCOLD · Understanding the influence of sediment dynamics on postglacial landscape evolution

Repeated glacial-interglacial cycles during the Quaternary have significantly impacted the topography of many mountain ranges around the world. Yet, the response of landscape evolution to repeated climate oscillations has not been well quantified. In recently deglaciated landscapes, the transition from glacial to fluvial/hillslope processes have induced progressive topographic adjustments, and the large amounts of sediments inherited from glacial periods and generated through landsliding of oversteepened glaciated topography may act as a fundamental control on the incision of postglacial rivers. These sediments can enhance fluvial incision rate by providing more tools for erosion, or inhibit incision by armoring the river bed. Characterizing when and where sediment enhances or inhibits fluvial incision in postglacial landscapes is critical for understanding the changes in postglacial landscape evolution rates over time and quantifying the response times of mountain ranges to deglaciation. In this project, I propose to develop a landscape evolution model to account for the complex impact of sediment dynamics on fluvial incision in postglacial landscapes. I will utilize this model to investigate the response of fluvial incision to changes in sediment supply and assess the effects of sediment on postglacial landscape evolution. I will apply the model to quantify response times of the deglaciated European Alp, leveraging the rich observational datasets in this region. The proposed work will provide a quantitative understanding of postglacial fluvial incision histories, which is critical for ecosystem management and natural hazard assessment in recently deglaciated mid-latitude mountain ranges and perhaps in high-latitude mountain ranges where continued climate change may eventually lead to deglaciation.