Permafrost thaw affects mass soil erosion with potential for eutrophication of the Arctic Ocean under continued climate change

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1 Permafrost thaw affects mass soil erosion with potential for eutrophication of the Arctic Ocean under continued climate change Joseph White 1, Ram Neupane 1,2, Neal Scott 3, Scott Lamoureux 3, Melissa Lafrenière 3 1 The Institute of Ecological, Earth/Department of Biology, and Environmental Science, Baylor University, Waco, Texas, USA 2 Department of Plant Science, South Dakota University, Brookings, South Dakota, USA 3 Department of Geography, Queens University, Kingston, Ontario, Canada

2 Watersheds: canary in the coal mine

3 The Arctic climate threat that nobody s even talking about yet Chris Mooney April 1, 2015 In this Aug. 10, 2009, photo, a hill of permafrost slumping from global warming near the remote, boggy fringe of North America, 2,200 kilometers (1,400 miles) from the North Pole, where researchers are learning more about methane seeps in the 25,000 lakes of this vast Mackenzie River Delta, in the Northwest Territories, Canada.(AP Photo/Rick Bowmer)

4 Active layer Ice rich permafrost 70% by volume Ice wedge Redrawn from

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6 LIVERPOOL BAY AND TUKTOYAKTUK PENINSULA, CANADA

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10 Cape Bounty Arctic Watershed Observatory (CBAWO), Melville Island

11 Background Cape Bounty Arctic Observatory, Melville Island, Nunavut Understand continued climate change impacts of terrestrial to marine sources of carbon and nutrients from Arctic watersheds Use of SWAT to assess potential fluxes in an experimentally challenging environment

12 SWAT Data Landcover IKONOS 2008, F. Gregory (200MSc thesis, Queens Univ) DEM used to derived topographic soil index as a surrogate for soil depth (max depth 50 cm) Daily meteorology derived from NCEP reanalysis Station located at W N Includes min/max temperature, precipitation, solar irradiance, and wind

13 Daily Average Total Solar Irradiance (MJ/m2/day) Monthly Average Precipitation (mm) Temperature ( C) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Tmax Tmin Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Not the actual station!

14 Usersoil Soil Characteristic Value Reference Bulk Density g/cm3 1.0 Michaelson et al.1996 Available Water Content (mm H2O/mm soil) Saturated Hydraulic Conductivity (mm/hr) Organic Carbon Content (%) Bölter et al Derived from Clapp and Hornberger (1978) based on %sand, silt, clay 1.9 Bölter et al Clay Content (%) 29 Bölter et al Silt Content (%) 45 Bölter et al Sand Content (%) 26 Bölter et al Rock Fragment Content (%) 60 Bölter et al Moist soil albedo 0.16 Chapin et al USLE K (Mg m2 hr/m3 Mg cm) 0.31 Computed based on Wischmeier and Smith (1978)

15 Stream Discharge (cms) SWAT Stream Discharge (cms) SWAT Calibration Discharge Data, West Lake, Jun 15 Aug 9, SWAT Observed y = 0.75x r 2 = 0.74 RMSE = 0.12 cms Observed Stream Discharge (cms) Description SWAT Default Calibrated Baseflow alpha factor (Days) Deep aquifer percolation fraction Groundwater delay time (Days) 31 1 Hydraulic conductivity in channel alluvium (mm/hr) 0 480

16 Simulated Stream Discharge (cms) SWAT Stream Discharge West Lake /1/1980 1/1/1984 1/1/1988 1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008

17 Yearday of Peak Stream Discharge 195 SWAT Peak Flow Day West Lake Anomaly or trend? Year Pre-2006, mean peak flow June 29 Post-2006, mean peak flow June 21

18 Annual Precipitation (mm) Sum of Daily Relative Humidity Temperature ( C) Annual Irradiance (MJ/m 2 ) SWAT Meteorological Variables Met Station W N Temperature y = x y = x y = x Tmax Tmin Tavg Solar Radiation Precipitation y = x Humidity 1000 y = x

19 SWAT N (mg/l) N-NO 3 +N-NO 2 (mg/l) Dissolved Organic N (mg/l) Initial Nutrient Results Solute Data, West Lake, Jun 15 Aug 9, June July Aug June July Aug Observed SWAT Observed SWAT N-NO3+N-NO2 Organic N \1 1984\1 1987\1 1990\1 1993\1 1996\1 1999\1 2002\1 2005\1 2008\1 Year/Month

20 Factor of Safety (F s ) Lewkowicz and Harris (2005) F s = c + z γ mγ w cos ² β tan φ zγ sin β cos β cʹ - effective cohesion (assumed 5 kpa) z depth of slip (m) γ unit weight of soil γ w unit weight of water m ratio of height of water table above slip to depth of slip surface (z) β slope angle ( ) φ ʹ effective angle of friction (assumed 27 )

21 SWAT-derived F s Prediction June 15, 2008 July 1, 2008

22 Summary Stream discharge declining over time; day of peak flow recently earlier Current model does not assess melting permafrost inputs Climate warmer, less precipitation, sunnier, drier Conditions lead to less snowpack with lower isothermal conditions for melting Model prediction of nitrogen sources similar, though underestimating organic decomposition Soilfluction processes approximated through depth to water table; controlled by depth to permafrost