Field And Laboratory Study Of Infiltration Processes During Melt Events In Frozen Prairie Soils
Date
2021-08-10
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Abstract
In the northern hemisphere snowmelt infiltration into frozen ground can be dependent on preferential flow along larger pores called macropores which can play a critical role in directing snowmelt for groundwater storage. Areas like the Canadian Prairies can undergo two or more melt events in a year which can change the soil storage capacity and influence how snowmelt is partitioned between infiltration and runoff during spring. The effects of these ‘mid-winter’ melt events on soil pore networks are not well understood, making it difficult to incorporate them in hydrological models. This study investigated the infiltration processes during melt events by performing a series of tracer tests on a cropland and grassland site and a set of infiltration experiments on frozen soil columns. Results from the laboratory study show that macropore flow is the dominant transport mechanism during melt events leading to deep percolation and minimal interaction between infiltrating water and the soil matrix. Snowmelt that infiltrates during mid-winter melt events infiltrate and refreezes in air-filled soil matrix pores first which, along with the heat energy exchanged between the soil matrix and infiltrating water, can result in snowmelt from later melt events to refreeze in macropores as ice “plugs” rather than completely blocking a macropore network. This reduces infiltration in frozen soils during spring melt, encouraging more runoff and ponding. Macropore connectivity can affect infiltration rates as seen with the greater runoff ratios on the cropland site which was less macroporous than the grassland site. It can also influence refreezing dynamics in pores as runoff was not always necessarily higher on croplands during spring melt.
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Citation
Khawaja, S. (2021). Field And Laboratory Study Of Infiltration Processes During Melt Events In Frozen Prairie Soils (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.