freeze-thaw cycle effects on ... - people.ucalgary.ca
TRANSCRIPT
Freeze-Thaw Cycle Effects on Groundwater and Surface Water Interaction Amber KobesUniversity of CalgaryGLGY 699: Seminar Presentation
Outline
1. Introduction
2. Study Area
3. Methodology
4. Research Findings
5. Future Considerations
Introduction
Seasonal fluxes in the water level
Primarily in the shallow Groundwater Bearing Zone (GBZ)
Areas with discontinuous permafrost and seasonally frozen soils vary from continuous permafrost zones and warmer climates
Water can exist as liquid, ice, and vapour
Important for resource management
water redistribution and run-off
Engineering designImage sourced from Ireson, et al. 2013
Interaction: Summer
SW-GW interaction affected by:
lateral and vertical flow
baseflow
infiltration
evapotranspiration
runoff
vadose zone soil moisture (capillary)
Interaction: Winter
SW-GW interaction affected by:
lateral flow
baseflow
evapotranspiration
Baseflow is a source of water >0C
Interaction: Freeze-Thaw
Freeze-thaw cycle influences infiltration
primarily for shallow aquifers
Water and ice will exist in different
pores of the soil
Methodology
Hydrogeology Journal (2013) by Ireson et al.
Irdeson et al. combined a theoretical approach with field studies
Study Area: semi-arid region at Duck Lake, Warman and Outlook
Semi-arid
Topographically driven flow
Focus on freeze-thaw cycles in the vadose zone to provide a
conceptual site model
Movement of Water
Infiltration TypesRestricted: Snowmelt Runoff
Limited: Snowmelt Runoff and Infiltration dependent on temperature and saturation
Unconditional: Infiltration dominant
Infiltration type determines the timing and magnitude of infiltration and runoff
Effects of snow cover
Insulating properties
Atmospheric temperature has less influence
Smaller freezing front
Driving Factor of Freeze-Thaw?
Image sourced from Xie, et al. 2021
Grain size distribution affects freezing-
thawing cycles
Larger pores freeze first and thaw last
As temperatures approached 0C, reductions
in hydraulic conductivity were similar to air-
drying soil curves
Image sourced from Watanabe and Flury 2008
Groundwater Recharge
Snowmelt runoff will generate ponding in local topographic depressions
Ponded water causes ice below depressions to thaw faster than surrounding frozen zones creating Depression-Focused Recharge
Annual variability in Depression-Focused Recharge
Prairie wetland ponds are a primary source of water for aquifers
Isotopic composition is variable between wetland ponds that seasonally form in depressions and ponds having a constant water supply
Image sourced from Hayashi et al. 2003
Groundwater Recharge
Increase in storage in winter through to early spring (~100 mm, Duck Lake)
Reduced evapotranspiration
Slow discharge from surficial aquifer
Groundwater Recharge~60 mm in spring
Water at 0.1C is evidence of complete thawing
Vertical gradient upwards in the Spring and Downwards in the Fall
Baseflow Recession
Recharge from frozen ground and runoff affect methods used to model baseflow
recession
Suggests that frozen ground reduces baseflow in the winter due to reduced infiltration
Important study for areas with an increasing active layer
Further Research Implications
Ineffective monitoring in frozen conditions
How to accurately measure liquid water content?
Gravimetric and neutron probes – cannot distinguish between ice and liquid
Time domain reflectrology – difficult calibration
Estimation of groundwater flow in relation to proportions of net
infiltration vs vertical redistribution is limited
Studies recommended to investigate moisture below the freezing front
How increasing active layers will impact groundwater discharge
Study Findings
Interaction between soil and groundwater was controlled by atmospheric
conditions and topographically driven lateral groundwater flow
Larger pores freeze first and thaw last significantly impacting hydraulic
conductivity
Freezing induced groundwater is affected by:
Initial water table depth
Snow cover
Rate of groundwater inflow
Freeze-thaw cycles impact the water level height in the shallow zone but do
not necessarily reflect a gain or loss of water from the subsurface.
Questions
References
(1) Hong-Yu Xie, Xiao-Wei Jiang, Shu-Cong Tan, Li Wan, Xu-Sheng Wang, Si-Hai Liang, and Yijian Zeng. 2021. Interaction of soil water and groundwater during the freezing-thawing cycle: field observations and numerical modelling. Hydrology Earth System Science. 25. 4243-4257
(2) A. M. Ireson & G. van der Kamp & G. Ferguson & U. Nachshon & H. S. Wheater. 2013. Hydrogeological processes in seasonally frozen northern latitudes: understanding, gaps and challenges. Hydrogeology Journal. 21. 53-66.
(3) McGinn, Sean. 2010. Weather and Climate Patterns of Canada’s Prairies. Anthropods of Canadian Grasslands.
(4) Hayashi, M., van der Kamp, G., and Schmidt, R. 2003. Focused infiltration of snowmelt water in partially frozen soil under small depressions. Journal of Hydrology 270 (3-4). 214-229
(5) Wananabe, K. and Flury, M. 2008. Capillary bundle model of hydraulic conductivity for frozen soil. Water Resources Research 44(12).
(6) Bam, E. K. P., Ireson, A. M., van der Kamp, G., & Hendry, J. M. (2020). Ephemeral ponds: Are they the dominant source of depression-focused groundwater recharge?. Water Resources Research, 56, e2019WR026640. https://doi.org/10.1029/2019WR026640