Thawing of Permafrost Peatland Hydrological Implications Masaki Hayashi

Thawing of Permafrost Peatland Hydrological Implications Masaki Hayashi 1, Bill Quinton 2, Alastair Mc. Clymont 1, Larry Bentley 1, Brendan Christensen 1 1 Geoscience, University of Calgary 2 Geography & Env. Studies, Wilfrid Laurier University

Prediction of Permafrost Thaw, 1990 -2090 Scotty Creek Hay River Lowland Model Assumptions • Vertical energy transfer • Large ( 50 km) grids • No lateral flow of water and energy Reality (Scotty Creek) pink: complete thawing Zhang et al. (2008. lake Geophys. Res. Lett. , 35: L 02502) peat plateau isolated bog connected bog channel fen 1 km

Annual Total Basin Runoff near Ft. Simpson precipitation (mm) annual runoff (mm) Four Rivers (150 -1, 900 km 2), Similar Landcovers Runoff = Total flow / Drainage area

flat bog peat plateau channel fen

Peat Plateaus Have Permafrost Cores channel fen Water flows over frozen peat. permafrost bog

Frost Table in Late August 2006 GS: ground surface FT: frost table ground surf. 0. 5 m 0. 9 m frost table

Differential Thawing by Conduction zf T = Ts l (W m-1 K-1) ground srf. Qm T=0 frost table Conduction dominates heat flux. Qm = lb (Ts – 0) / zf lb : bulk thermal conductivity water content Wet spots thaw faster. Hayashi et al. (2007, Hydrol. Proces. 21: 2610 -2622)

2 D Survey of Frost Table (FT) June 12, 2006 ground surf. FT • FT measured using FT probe on 0. 25 m grids. • Subsurface flow simulation: 15 mm of rain added. Boussinesq equation is numerically solved. Wright et al. (2009, Water Resour. Res. 45: W 05414)

Electrical Resistivity Imaging (ERI) fen bog 0 m 0 m 5 fen 20 FT plateau 40 permafrost 10 15 20 resistivity (W m) 60 bog 80 unfrozen peat clay 102 103 104

ERI Line 1: Peat Plateau Transect 20 m 0 2 depression 30 40 50 60 4 0 m 0 m 5 fen 20 FT plateau 40 permafrost 10 15 20 resistivity (W m) 60 bog 80 unfrozen peat clay 102 103 104

ERI Line 2: Cross-Bog Transect 100 m fen 0 m 0 m isolated bog 20 40 bog 60 80 5 10 15 20 clay sand lens resistivity (W m) 102 103 104

Conceptual Model of Permafrost Thaw peat plateau 1. Thinning of canopy. Increase in radiation energy input. 2. Local thawing. Water-energy feedback causes further thawing. 3. Wet condition prevents trees from growing back. New bog forms. unsaturated, thawed peat saturated, frozen peat 1 2 preferential thaw new bog 3

Delineation of Peat Plateau on Aerial Images 1977 200 m Quinton et al. (2011, Hydrol. Proces. , 25: 152)

Delineation of Peat Plateau on Aerial Images 2008 Peat Plateau Area 1977: 53% 2008: 43% 200 m Quinton et al. (2011, Hydrol. Proces. , 25: 152)

Changes Evident on the Ground Aug. 2002 July 2010 Datalogger

Modelling Peat Plateau Runoff Hydraulically equivalent plateau Drainage of groundwater controlled by: - Radius - Gradient - Ksat distribution - Frost-table depth 200 m Similar to MESH, but the moving FT is the challenge.

Coupled Permafrost-Hydrology Model for Circular Peat Plateau vertical transfer lateral drainage Northern Ecosystem Soil Temperature (NEST) model Zhang et al. (2008) Simple Fill and Spill Hydrology (SFASH) model Wright et al. (2009)

frost table (m) NEST-SFASH Preliminary Results water flux (mm/d) J F M A M J J A S O N D 2009 2010

Challenges and the Way Forward 1. Storage and flow of runoff water in the fen-bog network Basin-scale hydrological model. 2. Incorporate lateral thawing of permafrost in longterm model simulation (e. g. 50 years). 3. Ecology-hydrology feedback processes. IP 3 Legacy 1. Scotty Creek research basin 2. Close collaboration with the local First Nation. 3. WLU-Northwest Territories Partnership for Research and Training (2010 -2020, $10 M project).

Acknowledgements People Nicole Wright, Laura Chasmer, Chris Hopkinson, Tyler Veness, Rob Schincariol, and many others Funding IP 3 Network International Polar Year Natural Sciences and Engineering Research Council Canada Research Chair Program Environment Canada Science Horizons Program Logistical Support Water Survey of Canada Environment Canada (NWRI) Liidlii Kue First Nations