Isotope-based assessment of water balance along chain-oflakes drainages in the continental Arctic and Subarctic of
Canada
John J. Gibson1,2, R. Reid3
1Alberta
Innovates Technology Futures, CANADA
2Geography, University of Victoria, CANADA
3Aboriginal Affairs and Northern Development, Yellowknife, CANADA
Regional survey of continental Arctic – 255 lakes
Precip. = 325 mm/yr; humidity = 0.65; 100-140 days ice-free
Isotope distribution in lakewater and precipitation
d18O in Precipitation
Gibson and Edwards, 2002
Isotope mass balance
Small Lake – No Atmospheric Feedback
Upwind
Precipitation dP
Atmosphere
Evap. Flux
weighted
Lake
Amount
or flow
weighted
dU, U
dR, R
dG, G
dA, h
dA, h
}
dI, I
Initial dE,E
dE,E
dA, h
kinetic
exchange
8
dP, P
8
equilibrium
exchange
equilibrium
exchange
dL, V
dQ , Q
Isotope mass balance
Small Lake – No Atmospheric Feedback
Upwind
Precipitation dP
Atmosphere
Evap. Flux
weighted
Lake
Amount
or flow
weighted
dU, U
dR, R
dG, G
dA, h
dA, h
}
Initial dE,E
dI, I
Runoff or Water Yield
dE,E
dA, h
kinetic
exchange
8
dP, P
8
equilibrium
exchange
equilibrium
exchange
dL, V
dQ , Q
Features of model
•
•
•
•
•
•
Isotopic and hydrologic steady-state
C-G parameterization
Fully-turbulent kinetic fractionation (CK18=14.3, CK2= 12.5)
Atmospheric moisture equilibrium (but evap. flux weighted to account for
seasonality and frozen conditions in winter)
Validated against energy balance and aerodynamic E methods
Reproduces slope of LEL ~5.5
Gibson et al. 2008, Global Biogeochem. Cycles
Key indicators
E dI dL

I dE dL
E
E

ET P  WY
Gibson and Edwards, 2002
Regional water balance
Gibson and Edwards, 2002
Central Arctic – 255 lakes
Salmita: Chain-of-lakes model
h,dA
R1 0
P1 ,dP
E1, dE1
R2 ,dP
P2 ,dP
E2, dE2
R3 ,dP
P3 ,dP
E3, dE3
Q2, dL2
V1, dL1
V2, dL2
Da m
seepa ge
R4 ,dP
P4 ,dP
E4, dE4
R5 ,dP
P5 ,dP
E5, dE5
Q4, dL4
Q3, dL3
Q5, dL5
V4, dL4
V5, dL5
Powder Ma g L.
Sandy Lake
V3, dL3
Ind ex La ke
Upper Pond
Lower Pond
Tailings Conta inment Area
Ha mbone L.
R6 ,dP
P6 ,dP
E6, dE6
Q6, dL6
V6, dL6
Trans Sa ddle L.
Ga uged
2011
2010
2009
2008
2007
-12
2006
Sandy Lake
2
-18
-20
-22
-10
-14
-18
-22
d H (‰ V-SMOW)
2011
2010
2009
2008
2007
2006
2005
-10
L
-22
PowderMag Lake
-80
-14
LEL slope ~5.6
-140
Snow
-35
-30
-25
G
M
W
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
18
d O (‰ V-SMOW)
-12
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
18
d O (‰ V-SMOW)
-12
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
18
d O (‰ V-SMOW)
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
18
d O (‰ V-SMOW)
Salmita: a 20-year record
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
-22
-10
Snowmelt simulation
-12
Salmita Lower Pond
-14
-16
-18
-20
-22
-10
Hambone Lake
-14
-16
-18
-20
-60
-100
-16
Evap. Pans
-120
Rain
-20
Tailings Ponds
-160
Natural Lakes
-180
-200
Mean annual precipitation
-16
-220
-20
-240
-15
d18O (‰ V-SMOW)
-10
-5
0
Gibson and Reid, 2014
Salmita: Results
4.0e+5
3.0e+5
2.0e+5
1.0e+5
0.0
2.5e+6
(b)
2.0e+6
1.5e+6
1.0e+6
1.2
5.0e+5
1.0
0.0
1e+6
(c)
8e+5
T
Hambone Lake
Powder Mag Lake
Sandy Lake
Lower Pond
0.8
0.6
E/I
0.4
4e+5
0.2
2e+5
0
0.0
0.5
(d)
0.4
E/ET
4.0e+5
3.0e+5
2.0e+5
0.3
0.2
E/ET
0.1
0.0
1.0e+5
-0.1
0.0
2.5e+6
1.0
Gauged at Sandy L.
outflow
2.0e+6
(e)
1.5e+6
0.8
Q/P
3
Evaporation (m )
3
0.84
0.80
0.76
0.72
0.68
0.64
h
6e+5
5.0e+5
Discharge (m )
16
14
12
10
8
6
4
2
500
400
300
200
100
0
1.4
Rel. Humidity
(a)
Precip. (mm) Temp. (deg C)
5.0e+5
E/I
3
Precipitation on Lake (m )
3
Land Runoff(m )
Inflow from Upstream
3
Lake/Reservoir (m )
Key indicators
Lower Pond
Hambone Lake
Powder Mag Lake
Sandy Lake
Hydrologic fluxes
0.6
Runoff ratios
0.4
0.2
1.0e+6
0.0
5.0e+5
1990
0.0
1995
2000
2005
2010
Year
1990
1995
2000
2005
2010
Year
Gibson and Reid, 2014
Gibson and Reid, 2014
Yellowknife: a 20-year record
-8
-12
-14
18
d O /‰VSMOW
-10
-16
Baker Cr.
Pocket Lake
-18
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
Year
Duckfish
Lake
WEST BAY
FAULT
-8
-12
0
r=
2
. 74
-convergence/divergence
Indicative of connectivity
-partitioning of E and T
-runoff ratios
7
-14
1:
1
d18O Pocket Lake
-10
-16
G
GIANT MINE
-18
WATER
DIVIDE
Lower
Martin Lake
-18
-16
-14
-12
-10
-8
Mouth @ Yellowknife Bay
Pocket
Lake
d18O Baker Creek
Airport
YELLOWKNIFE
0
1 2
3 4
5 km
YELLOWKNIFE BAY
Gibson and Reid, 2010
E/I
e.
Isotope partition method
E/ET
Watershed budget, fully connected
f.
Topographic Drainage Area
85%
Connectivity
2014
2011
2012
2013
2008
2009
2010
2005
2006
2007
2002
2003
2004
1999
2000
2001
25 %
1996
1997
1998
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
160
140
120
100
80
60
40
20
b.
1993
1994
1995
2.5
2.0
1.5
1.0
0.5
0.0
1990
1991
1992
upper limit
2
eff. dba (km )
E/ET
E/I
Key indicators
Gibson and Reid, 2010
1.2
Comparison of sites
Hambone Lake
Powder Mag Lake
Sandy Lake
Baker Creek (YK)
(a)
1.0
0.8
E/ET
-Yellowknife: greater E/ET, similar to
findings of the regional survey
-Salmita: E/ET greater in low precip.
years (when landscape is dry)
0.6
0.4
0.2
0.0
150
200
250
300
350
400
450
Precipitation (mm)
1.2
Hambone Lake
Powder Mag Lake
Sandy Lake
Baker Creek (YK)
(b)
1.0
Discharge/Precipitation
-Runoff ratios variable but tend to be
greater at Salmita in low precip.
years (due to role of active-layer
storage)
0.8
0.6
0.4
0.2
0.0
150
200
250
300
Precipitation (mm)
350
400
450
Gibson and Reid, 2014
Conclusions
•
Consistent water budget results were obtained from two sitespecific studies and a regional survey across the continental Arctic
•
No pronounced unidirectional shifts were observed in the water
balance at the sites due to climate change over the past two
decades – driven by snowpack, ice-cover duration, P, E
•
Isotope mass balance provides a basis for estimating water
balance at remote under-monitored locations for gauged and
ungauged basins in a seasonally arid region of Canada.
Weighting and Atmospheric Feedback
Large Lake – Atmospheric Feedback
Upwind
Precipitation dP
Atmosphere
Evap. Flux
weighted
Lake
Amount
or flow
weighted
dU, U
dR, R
dG, G
dA’, h’
dA, h
}
dI, I
Initial dE,E
dE’,E’
dA’, h’
kinetic
exchange
8
dP, P
8
equilibrium
exchange
equilibrium
exchange
dL, V
dQ , Q
100
W
Global Surface Waters
M
G
H (‰V-SMOW)
50
2
L
SMOW
0
-50
-100
-150
-200
-30
-20
-10
18
0
10
20
O (‰ V-SMOW)
Evaporative enrichment in lakes
Jasechko et al., 2013, Nature
Isotope exchange at air-water interface:
CRAIG
AND
GORDON
MODEL
Atmospheric moisture
Lakewater
Gat, Ann. Rev. Earth Planet Sci.,1996
Equilibrium fractionation
Majoube, 1971, J. Chim. Phys.
Horita and Wesolowski, 1994, Geochim. Cosmochim. Acta
Kinetic fractionation
Horita et al. 2008, Isot. Environ. Healt. S. (review)
1
dE 
1 h  K
equilibrium
separation
dL  

 hd A   K



kinetic
separation
Evaporating moisture



kinetic
separation
Isotope Mass Balance Models
Water mass balance
Isotope mass balance
dV
 I Q E
dt
dL
Isotopic and hydrologic steady state
dV
dd
 V L  d I I  d QQ  d E E
dt
dt
Other forms
-Volumetric changes
E dI dL

I dE dL
-Isotopic changes
-Stratified
Offset from MWL
controlled by
E/I balance
dI
dL (E/I=1)
... 
dd L I
E
 d I  d L   d L  d E 
dt V
V

It 
d L  d S  d S  d 0  exp  1  mx 
V

X epi  hyp 
V
 d ( hyp)  d L  
 d ( hyp)  d L 
V
V
dL (E/I=1)
dL (E/I=0.1)
dL (E/I=0.1)
dI
Temporal enrichment to isotopic
steady-state shown to depend on E/I
Atmospheric moisture
Equilibrium assumption
-valid for long time-periods
-continental regions
Precipitation
**must be weighted by evaporation flux
d A  d P    /  
Equilibrium moisture
Flux-weighted equilibrium moisture
Gibson et al., 2008, Global Biogeochem. Cycles
Seasonality effect on LEL
S LEL
 h(d A  d P )  (1  d P )( K    /   ) 


h K   / 

2

 h(d A  d P )  (1  d P )( K    /   ) 


h K   / 

18