Thawing of Permafrost Peatland and Hydrological Implications

Thawing of Permafrost Peatland and Thawing of Permafrost Peatland and Hydrological ImplicationsHydrological Implications

Masaki HayashiMasaki Hayashi11, Bill Quinton, Bill Quinton22, Alastair McClymont, Alastair McClymont11, , Larry BentleyLarry Bentley11, Brendan Christensen, Brendan Christensen11

11Geoscience, University of CalgaryGeoscience, University of Calgary22Geography & Env. Studies, Wilfrid Laurier UniversityGeography & Env. Studies, Wilfrid Laurier University

Prediction of Permafrost Thaw, 1990-2090

pink: complete thawing

Model Assumptions• Vertical energy transfer• Large (50 km) grids•No lateral flow of water and energy

Zhang et al. (2008. Geophys. Res. Lett., 35: L02502)

Reality (Scotty Creek)

1 km

lakepeat plateauisolated bogconnected bogchannel fen

Hay River Hay River LowlandLowland

Scotty CreekScotty Creek

0

200

400

600

1970 1980 1990 2000 2010

Ft. Simpson precip.

pre

cip

itat

ion

(m

m)

0

100

200

300

400

1970 1980 1990 2000 2010

BirchJean-MarieBlackstoneScotty

an

nu

al r

un

off

(m

m) Runoff = Total flow / Drainage area

Annual Total Basin Runoff near Ft. SimpsonFour Rivers (150-1,900 km2), Similar Landcovers

channel fenchannel fen

flat bogflat bog

peat plateaupeat plateau

permafrostpermafrost

Peat Plateaus Have Permafrost Cores

Water flows over frozen peat.

channel fenchannel fen

bogbog

-1.5

-1

-0.5

0

0.5

1

0 10 20 30 40

rela

tiv

e e

lev

ati

on

(m

)

distance from fen (m)

ground surf.

frost table

0.5 m0.9 m

Frost Table in Late August 2006GS: ground surface FT: frost table

zf

T = 0

T = Ts

frost table

ground srf.

Qm

Conduction dominates heat flux.

Qm = b (Ts – 0) / zf

b : bulk thermal conductivity

Hayashi et al. (2007, Hydrol. Proces. 21: 2610-2622)

0.1

0.2

0.3

0.4

0.5

0.4 0.5 0.6 0.7 0.8

Measuredde Vries Eqn.

(

W m

-1 K

-1)

water content

Differential Thawing by Conduction

Wet spots thaw faster.

2D Survey of Frost Table (FT)June 12, 2006

ground surf.

FT

• FT measured using FT probe on 0.25 m grids.

Wright et al. (2009, Water Resour. Res. 45: W05414)

• Subsurface flow simulation: 15 mm of rain added.Boussinesq equation is numerically solved.

Electrical Resistivity Imaging (ERI)

fenfen

bogbog

0 m 20 40 80fen plateau bog0 m

15

5

10

20

60

resistivity ( m)

102 103 104

FTclayclay

unfrozen peatunfrozen peatpermafrostpermafrost

0 m 20 40 80fen plateau bog0 m

15

5

10

20

60

resistivity ( m)

102 103 104

FT

ERI Line 1: Peat Plateau Transect

0

2

4

20 m 30 40 50 60

clayclayunfrozen peatunfrozen peat

permafrostpermafrost

depression

100m100m

ERI Line 2: Cross-Bog Transect

0 m 20 40 80fen isolated bog bog

0 m

15

5

10

20

60

resistivity ( m) 102 103 104

clayclayclayclay

sand lens

Conceptual Model of Permafrost Thaw

saturated, frozen peatsaturated, thawed peatunsaturated, thawed peat

new bog

1

2

3

preferential 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.

19771977

Delineation of Peat Plateau on Aerial Images

200 m

Quinton et al. (2011, Hydrol. Proces., 25: 152)

20082008

Delineation of Peat Plateau on Aerial Images

Peat Plateau Area

1977: 53%

2008: 43%

200 m

Quinton et al. (2011, Hydrol. Proces., 25: 152)

Aug. 2002Aug. 2002

DataloggerDatalogger

Changes Evident on the Ground

July 2010

DataloggerDatalogger

200 m

Modelling Peat Plateau RunoffModelling Peat Plateau Runoff

Hydraulically equivalent plateau

Drainage of ground-water controlled by:- Radius- Gradient- Ksat distribution- Frost-table depth

Similar to MESH, but the moving FT is the challenge.

Coupled Permafrost-Hydrology Model for Circular Peat Plateau

Northern Ecosystem Soil Temperature (NEST) modelZhang et al. (2008)

vertical transfer

Simple Fill and Spill Hydrology (SFASH) modelWright et al. (2009)

lateral drainage

NEST-SFASH Preliminary Resultsfr

ost

tab

le (

m) 0

0.2

0.4

0.6

0.8simulatedobserved

J F M A M J J A S O N D J F M A M J J A S O N D2009 2010

0246

runoff

J F M A M J J A S O N D J F M A M J J A S O N D2009 2010

0

20

40 rainsnow melt

wat

er f

lux

(mm

/d)

L

LL

LL

L

L

L

L

Challenges and the Way Forward1. Storage and flow of runoff water in the fen-bog

network Basin-scale hydrological model.

2. Incorporate lateral thawing of permafrost in long-term model simulation (e.g. 50 years).

3. Ecology-hydrology feedback processes.

IP3 Legacy1. Scotty Creek research basin

2. Close collaboration with the local First Nation.

3. WLU-Northwest Territories Partnership for Research and Training (2010-2020, $10M project).

PeopleNicole Wright, Laura Chasmer, Chris Hopkinson, Tyler Veness, Rob Schincariol, and many others

FundingIP3 NetworkInternational Polar YearNatural Sciences and Engineering Research CouncilCanada Research Chair ProgramEnvironment Canada Science Horizons Program

Logistical Support Water Survey of CanadaEnvironment Canada (NWRI)Liidlii Kue First Nations

Acknowledgements