Icy landscapes from the Brooks Range to the Beaufort Sea: Quantifying the mobilization, transport and deposition of sediment and carbon in Arctic Alaska

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Arctic landscapes are rapidly changing because of ongoing warming. One effect of this warming is that permafrost, which is ground that remains frozen even in summer, is now thawing. Permafrost thaw exposes previously frozen organic soil material to decomposition, a process that releases carbon dioxide to the world’s atmosphere and can contribute to the greenhouse effect. Thaw also brings new amounts of soil and carbon material into Arctic rivers, which then gets deposited in floodplains and coasts. How the transport of this soil and carbon through river corridors and the burial of this material on the coasts, affect carbon decomposition is unclear. This project collects data that will monitor changes in water and carbon chemistry for the Canning River in Alaska. These measurements from the land surface, floodplain and river banks, will allow us to develop new theories about the carbon cycle. These new insights will be used to develop computer models that predict future landscape change and carbon release. The project will help build the future workforce through training of four students and a postdoctoral fellow in integrated data collection and computer modeling. We will share our insights with the public through a short film. We will also work with regional decision makers through close collaboration with the US Geological Survey, Fish and Wildlife Service, and at the National Park Service. Limited understanding of the mechanisms of sediment production in seasonally frozen landscapes, of transport, storage, and transformation of sediment and carbon along river corridors, and deposition at the coasts, prevents us from predicting Arctic carbon cycles into the future. This project addresses the geomorphic transport system and its connection to organic carbon liberation and sequestration. The study tracks sediment and carbon geochemical characteristics through the conveyor system of the Canning River on Alaska’s North Slope, from its glacial headwaters in the Brooks Range to its delta in the Beaufort Sea. We will develop new theory and quantitative numerical models. Field efforts, which include the establishment of time-lapse cameras along the Canning River, high resolution morphological change mapping using drones and the new Arctic Digital Elevation Model, deployment of temperature and sediment transport sensors, and the collection of water, sediment and carbon samples, will shed light on the magnitudes of sediment and carbon fluxes from the terrestrial domain to the coastal Arctic Ocean. These measurements will provide a baseline data set against which future change can be assessed. The study will address hillslope sediment transport by solifluction, thaw-controlled fluvial sediment transport, sediment comminution by frost cracking, thermal riverbank erosion, and deltaic deposition in a sea-ice-covered ocean. The numerical schemes developed in this project will improve existing open-source model frameworks for simulating high latitude, hydrology, biogeochemistry, and morpho-dynamics. This project will train graduate and undergraduate students in Arctic system science, geomorphology, and sedimentary processes, within the integrated context of field, laboratory, numerical modeling methods. This award is co-funded by the Arctic Natural Sciences Program and the Geomorphology and Land-use Dynamics Program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.