2019 CSDMS meeting-076
Constraining hydroclimate control on permafrost slope stability with sediment records, modern landscapes and coupled models
What are the topographic, thermal and hydrologic conditions setting slope stability in frozen and thawing landscapes? We address this question with past and present records to inform models to predict future landscape change. Relict periglacial landscapes and slope deposits constrain timing and magnitude of slope instabilities in past glaciations. Using sediment records from these deposits, we show how hillslope denudation varies as a function of climate at both the Last Glacial Maximum and previous Pleistocene glaciations. In central Pennsylvania, organic geochemistry and plant macrofossils provide ecological constraints on depositional environments and climate conditions in an upland bog with periglacial sedimentation. Nearby we use cosmogenic isotopes to constrain erosion rates and depositional ages of periglacial debris in toeslope deposits. Remote sensing and field surveys in western Alaska summer 2019 will document the topographic and hydrologic controls on modern slope stability, as well as accumulation rate of sediment in the past. Coupling landscape evolution models with permafrost models should be capable of both hindcasting climate conditions from past sedimentology and forecasting slope stability in modern permafrost landscapes. Such models will require soil mobility to be linked to frozen and unfrozen water content, to be developed in collaboration with CSDMS researchers.