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The NORTHThe NORTH--WATCH programWATCH programWe now have compelling evidence that climate change is
affecting water resources in many parts of the world. In few
places will the changes and challenges be greater than in the
higher mid-latitudes of the northern hemisphere. In this
circumpolar, transitional climatic zone, slight temperature
differences determine the status of frozen ground, whether
precipitation falls as rain or snow, and the degree to which winter
snow packs accumulate and subsequently melt. Predicting the
integrated consequences of climate change on the physical,
chemical and biological characteristics of water resources is a
difficult area of interdisciplinary environmental science.
Fortunately, in many areas, research catchments have been
established that provide the long-term data sets that encompass
integrated measurement of the linkages between the climate,
hydrology, biogeochemistry and ecology of river systems and
how these are being affected by climatic change.
North-Watch (http://www.abdn.ac.uk/northwatch/) is funded by
the Leverhulme Trust, UK, and lead by Doerthe Tetzlaff at the
Northern Rivers Institute, Univ. of Aberdeen, Scotland, UK.
BackgroundBackgroundThere has been an increasing interest in understanding the
regulating mechanisms of surface water dissolved organic carbon
(DOC) over the last decade. A majority of this recent work has been
based on individual well characterized research catchments or on
regional synoptic datasets combined with readily available
landscape and climatic variables. However, as the production and
transport of DOC is primarily a function of hydro-climatic
conditions, a better description of catchment hydrological
functioning across large geographic regions would be favorable for
moving the mechanistic understanding forward. To do this we
report from a first assessment of catchment DOC from the
international inter-catchment comparison program North-Watch.
Hydro-climatic controls of catchment DOC across northern
catchments within the North-Watch programHjalmar Laudon1, Doerthe Tetzlaff2,3, Sean Carey4, Chris Soulsby2, Jan Seibert5, Jim Buttle6, Jamie Shanley7, Jeff McDonnell8, Kevin McGuire9
HJ Andrews, Pacific NW, USKrycklan, N Sweden Strontian, ScotlandWolf Creek, Canada Mharcaidh, Scotland Girnock, Scotland
AffiliationsAffiliations1. Dept. Forest Ecology and Management, SLU, Sweden, [email protected]
2. Northern Rivers Institute, University of Aberdeen, Scotland, [email protected];
3. IGB Berlin Leibnitz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
4. Dept. Geography and Environ. Studies, Carleton Univ. Canada; [email protected]
5. Dept. Geography University of Zurich – Irchel, Switzerland, [email protected]
6. Dept Geography, Trent University, Canada; [email protected]
7. U.S. Geological Survey, Montpelier, USA; [email protected]
8. Dept Forest Engineering, Oregon State Univ., USA; [email protected]
9. Virginia Polytechnic Institute & State Univ., USA; [email protected]
Preliminary findingsPreliminary findings• Hydroclimatic conditions have profound control on DOC on
episodic, seasonal and inter-annual time scales across the northern
catchments.
•There is a strong seasonality in runoff and DOC export among all
catchments but it becomes successively more dominated by export
during the spring towards the sites in colder regions (Fig. 2&3).
•There is decoupling between runoff and DOC export, with a
generally lower relative export of DOC during winter and spring and
higher relative export during late summer and fall (Fig. 3).
•Winter temperature is a strong predictor of the proportion of
annual DOC that is exported during spring and early summer (Fig.
4).
Dry
Wet
Warm
Cold
Fig. 1. Catchments
included in the
North-Watch
program
Jan FebMar AprMay Jun Jul Aug Sep Oct NovDec
Proportion of annual flux (%)
0
10
20
30
40
50
J F M A M J J A S O N D
Jan FebMar AprMay Jun Jul Aug Sep Oct NovDec
Proportion of annual flux (%)
0
5
10
15
20
25
30
35
J F M A M J J A S O N D
Jan FebMar AprMay Jun Jul AugSepOct NovDec
Proportion of annual flux (%)
0
5
10
15
20
25
30
35
J F M A M J J A S O N D
Runoff
DOC
Jan FebMar Apr May Jun Jul Aug Sep Oct NovDec
Proportion of annual flux (%)
0
5
10
15
20
J F M A M J J A S O N D
Jan FebMar Apr May Jun Jul AugSepOct NovDec
Proportion of annual flux (%)
0
5
10
15
20
25
30
35
J F M A M J J A S O N D
Jan FebMar AprMay Jun Jul AugSepOct NovDec
Proportion of annual flux (%)
0
5
10
15
20
25
30
35
J F M A M J J A S O N D
Jan FebMar Apr May Jun Jul AugSepOct NovDec
Proportion of annual flux (%)
0
5
10
15
20
J F M A M J J A S O N D
Fig. 2. Ten year
monthly average
precipiation (P), runoff
(Q) and Evapo-
transpiration (ET).
Fig. 3. Ten year
average proportion of
total Q and DOC
export each month.
Tavg=9.2℃Pavg=2158 mm
Qavg=1744 mm
ETavg=412 mm
Tavg=9.1℃Pavg=2632 mm
Qavg=2213 mm
ETavg=417 mm
Tavg=6.7℃Pavg=1059 mm
Qavg=603 mm
ETavg=453 mm
Tavg=5.7℃Pavg=1222 mm
Qavg=873 mm
ETavg=326 mm
Tavg=4.9℃Pavg=980 mm
Qavg=577 mm
ETavg=401 mm
Tavg=4.7℃Pavg=1256 mm
Qavg=743 mm
ETavg=510 mm
Tavg=1.8℃Pavg=651 mm
Qavg=327 mm
ETavg=323 mm
Tavg=-2.2℃Pavg=478 mm
Qavg=352 mm
ETavg=127 mm
Fig. 4. Proportion of
DOC exported during
the spring and early
summer period
Average winter temperature (oC)
-16 -12 -8 -4 0 4 8
Proportion of DOC exported during spring (%)
0
20
40
60
80
100
r2=0.82p<0.001
Jan FebMar Apr May Jun Jul AugSepOct NovDec
Proportion of annual flux (%)
0
5
10
15
20
J F M A M J J A S O N D
Krycklan
Wolf Creek
HJ Andrews
DorsetSleepers
Girnock
Strontian
Mharcaidh