Hydrologic function of a bog cascade in thawing discontinuous

Hydrologic function of a bog cascade in
thawing discontinuous permafrost, Northwest
Territories, Canada
Connon, R.1, Quinton, W.1 , Craig, J.2 and Sonnentag, O.3
1Centre for
Cold Regions and Water Science, Wilfrid Laurier University
of Civil and Environmental Engineering, University of Waterloo
3Département de géographie, Université de Montréal
2Department
CCRN ECRN Day
October 19, 2014
Lower Liard River
Valley
Mackenzie
Basin
Streamflow changes in the lower Liard River valley
Runoff (mm)
700
700
600
600
500
500
400
400
300
300
200
200
100
100
0
1975
0
1980
1985
Birch
300
1990
1995
Blackstone
300
200
150
100
50
1986
1991
1996
2001
2005
Jean-Marie
Jean-Marie Runoff: 11 Year Moving Average
250
0
1981
2000
Scotty
Annual Runoff (mm)
Annual Runoff (mm)
800
Runoff and Precipitation: Lower Liard River Valley
Precipitation (mm)
800
2010
Precipitation
Birch Runoff: 11 Year Moving Average
250
200
150
100
2006
50
0
1981
1986
1991
1996
2001
2006
• Annual streamflows are deviating from their historical means
Why?
Runoff Processes
Runoff into Bog
Peat Plateau
Peat Plateau
Flat Bog
Flat Bog
Change in Permafrost Extent
Figure 6
1977
2010
Permafrost thaw is creating a more
integrated wetland system that is
fundamentally changing the storage and
flux of moisture in a basin
Bogs can connect with the channel fen in
one of two ways:
1) Open connection
- Bog and fen merge and form a
continuous hydrological connection
2) Channel connection
- A channel is formed which cuts
through the permafrost plateau and
drains into the fen during periods of
high moisture input
a)
b)
1977
2010
Isolated
Bogs
Channel
Fen
c)
Bog
Capture
Channel
Fen
d)
Routing of Precipitation Inputs
-
Primary runoff areas route moisture
directly to the channel fen
-
Each bog has it’s own ‘bogshed’
(i.e. runoff contributing area)
-
Ephemeral channels connect flat bogs and
drain into the channel fen, creating a “bog
cascade”
Flow through the bog cascade is
dependent on the depression storage
capacity in each bog. If the storage
capacity of a bog is not satisfied this
bog will not transmit moisture further
down the cascade
-
Isolated bogsheds never contribute to
flow
The Bog Cascade
Water is routed through
connected bogs during periods
of high moisture supply
Gauging Discharge
250
b)
Connection 105
6
200
5
150
4
Q (L/s)
Q (m3/day)
a)
100
3
2
R² = 0.96
50
0
0.00
Connection 105 May Discharge
0.02
0.04
Stage (m)
0.06
0.08
1
0
May 10
May 14
b)
May 19
May 23
May 27
Date
Three channels drain the plateaubog complex into the channel fen.
Total runoff from this complex in
May 2013 was 52 mm. Basin runoff
for May 2013 was 44 mm, indicating
that bog cascades are capable of
transmitting sufficient moisture
during periods of high connectivity.
Gauging discharge at one of three channels that drain out of the
peat-plateau complex and into the channel fen
a) Rating curve used calculated with instantaneous measurements
b) Hydrograph for snowmelt period (May)
c)
Flume box used to channel flow
Area
QOUT
Runoff
176 964 m2
9114 m3
52 mm
Thank you!
Questions?
Thank You!
Questions?