modelling groundwater transport and travel times in warming permafrost

1. Modelling groundwater transport and
travel times in warming permafrost
Andrew Frampton1,2, Romain Pannetier1,2, Georgia Destouni1,2
1 Department of Physical Geography and Quaternary Geology
Stockholm University, Sweden
2 Bolin Centre for Climate Research
Stockholm University, Sweden
2015-10-14 Grundvattendagarna, Göteborg

2. Motivation
• Permafrost is perennially frozen ground (T<0 for two consecutive years)
• Covers ~24% of northern hemisphere
• ~1700 Gt carbon stored in, more than twice atmospheric content
• Permafrost carbon feedbacks – links between changing permafrost,
hydrology, solute transport and carbon release
• How quantify changes in groundwater flow, discharge and transport

3. Motivation
• Permafrost landscapes can be extremely dynamic and vulnerable
Imgs: National Snow and Ice Data Center, University of Colorado, Boulder.

4. Motivation
Imgs: Policy Implications of Warming Permafrost, UNEP 2012.
• Permafrost landscapes can be extremely dynamic and vulnerable

5. • Highly transient – systems seasonally dependent, variably
isolated/connected leading to complex exchange patterns
• Need for improved mechanistic understanding of interactions
between changing permafrost and groundwater flow and transport
• Field measurements costly, sites generally very remote
Woo (2012)
After van Everdingen (1990)
Cryohydrogeology – Groundwater in cold regions

6. • Physically-based numerical model
• Couples mass and energy conservation equations for water transport
in partially frozen ground
• Accounts for
− Partitioning of water between the liquid, vapour, and ice phases
− Cryosuction
− Advective transport (liquid, vapour) and diffusive transport (vapour)
− Conductive and convective transport of heat and latent heat transfer
Cryohydrogeology – Groundwater in cold regions
Painter (2011) Comput Geosciences; Frampton et al (2011), J Hydrol; Frampton et al (2013), Hydrogeol J
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• Mass conservation equations
• Energy conservation equations

7. How do water flows and associated inert solute
transport change in degrading permafrost?
Painter (2011) Comput Geosciences; Frampton et al (2011), J Hydrol; Frampton et al (2013), Hydrogeol J

8. Zoomed detail
Note cryosuction
Permafrost degradation and flow pathways during
100 yrs simulated warming (0.05 °C/yr)
Legend
Liquid saturation
Icesaturation
Pre warming
MAST -1 °C

9. Legend
Liquid saturation
Icesaturation
Pre warming
MAST -1 °C
Year 1
MAST -1 °C
Post warming
MAST 4 °C
Year 100
MAST 4 °C
Permafrost degradation and flow pathways during
100 yrs simulated warming (0.05 °C/yr)
Horizontal distance (m)Horizontal distance (m)

10. Changes in travel times
Pre warming Post warming
• Several processes contribute to increase in travel times
• Pathway lengths increase with degrading permafrost
• Warming induces slow vertical flow percolation rather than fast
horizontal saturated groundwater flow
• Seasonal freezing re-routes the carrier flow by cryosuction which
increases travel times
• Seasonal freezing-induced immobilization increases total travel
times Frampton and Destouni (2015), WRR

11. • Several processes contribute to increase in travel times
• Pathway lengths increase with degrading permafrost
• Warming induces slow vertical flow percolation rather than fast
horizontal saturated groundwater flow
• Seasonal freezing re-routes the carrier flow by cryosuction which
increases travel times
• Seasonal freezing-induced immobilization increases total travel
times
Changes in travel times
Frampton and Destouni (2015), WRR

12. Summary
• Cryohydrogeology – Groundwater in cold regions
• Arctic systems are delicate and prone to climate change
• Northern permafrost environments contain significant amounts of frozen
carbon, primarily in near-surface layers, with seasonal groundwater flow
• Physically-based modelling of main processes can be used to quantify
both hydrological and permafrost change subject to climate change
• Subsurface water discharge and solute transport travel times increase
with warming temperature trends
• Transport pathways also increase and change – may significantly impact
reactive transport
• Further considerations include addressing carbon transport, linking to
arctic permafrost-hydrological climate feedback mechanisms

13. Thank you for your attention!
Questions?