January 06, 2020
Changes in Northern Alaska’s Land-to-Ocean River Flows
Warming and permafrost thaw is impacting the region’s terrestrial hydrological flows.
Through a synthesis of available measurements and state-of-the-art hydrological modeling, the research points to significant increases in the proportion of subsurface runoff and cold season discharge across the North Slope of Alaska, changes that are consistent with warming and thawing permafrost.
The Alaskan North Slope rivers carry carbon and other nutrients to the lagoon environments that are prominent components of the Beaufort Sea coast. The changing terrestrial inflows and other alterations connected with permafrost thaw may be influencing food web structure within the lagoons.
Scientists from the University of Massachusetts-Amherst investigated the changing character of runoff, river discharge, and other hydrological elements across the watershed draining the North Slope of Alaska over the period 1981–2010. Field measurements of discharge and other hydrological cycle elements in this region are sparse, requiring a modeling approach to quantify the land-ocean flows and their changing character. This synthesis of observations and modeling reveals significant increases in the proportion of subsurface runoff. Cold season discharge increases are 134% of the long-term average for the North Slope and 215% for the Colville River basin. The simulations point to a significant decline in terrestrial water storage, as losses in soil ice outweigh gains in soil liquid water storage. The timing of peak spring discharge shifted earlier by 4.5 days, consistent with earlier snowmelt thaw. These changes are consistent with warming and thawing permafrost and have implications for water, carbon, and nutrient cycling in coastal environments. The changing terrestrial inflows may be impacting biological productivity within the lagoons, upon which local native communities rely for their subsistence lifestyle.
University of Massachusetts-Amhearst
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
This research has been supported by the Office of Biological and Environment Research (BER, grant no. DE-SC0019462 to M. Rawlins), within the U.S. Department of Energy (DOE) Office of Science, and the DOE Next-Generation Ecosystem Experiments (NGEE)–Arctic project of BER’s Terrestrial Ecosystem Science program (D. Nicolsky). Support was also provided by the Beaufort Lagoon Ecosystems Long Term Ecological Research program (BLE LTER), under the National Science Foundation (NSF) Division of Polar Programs (grant no. NSF-OPP-1656026) and the National Aeronautics and Space Administration (NASA, grant no. 80NSSC19K0649). The study involved use of the Permafrost Water Balance Model v3.
Rawlins, M. A., L. Cai, S. L. Stuefer, and D. Nicolsky. "Changing characteristics of runoff and freshwater export from watersheds draining northern Alaska." The Cryosphere 13 (12), 3337–3352 (2019). https://doi.org/10.5194/tc-13-3337-2019.