Dual‐permeability modeling of preferential flow and snowmelt partitioning in frozen soils

Aaron A. Mohammed; Edwin E. Cey; Masaki Hayashi; Michael V. Callaghan; Young‐Jin Park; Killian L. Miller; Steven K. Frey

doi:10.1002/vzj2.20101

Effects of preferential flow on snowmelt partitioning and groundwater recharge in frozen soils

Hydrology and Earth System Sciences ◽

10.5194/hess-23-5017-2019 ◽

2019 ◽

Vol 23 (12) ◽

pp. 5017-5031 ◽

Cited By ~ 4

Author(s):

Aaron A. Mohammed ◽

Igor Pavlovskii ◽

Edwin E. Cey ◽

Masaki Hayashi

Keyword(s):

Soil Moisture ◽

Groundwater Recharge ◽

Preferential Flow ◽

Frozen Soil ◽

Time Lags ◽

Runoff Generation ◽

Frozen Ground ◽

Soil Matrix ◽

Frozen Soils ◽

Flow Through

Abstract. Snowmelt is a major source of groundwater recharge in cold regions. Throughout many landscapes snowmelt occurs when the ground is still frozen; thus frozen soil processes play an important role in snowmelt routing, and, by extension, the timing and magnitude of recharge. This study investigated the vadose zone dynamics governing snowmelt infiltration and groundwater recharge at three grassland sites in the Canadian Prairies over the winter and spring of 2017. The region is characterized by numerous topographic depressions where the ponding of snowmelt runoff results in focused infiltration and recharge. Water balance estimates showed infiltration was the dominant sink (35 %–85 %) of snowmelt under uplands (i.e. areas outside of depressions), even when the ground was frozen, with soil moisture responses indicating flow through the frozen layer. The refreezing of infiltrated meltwater during winter melt events enhanced runoff generation in subsequent melt events. At one site, time lags of up to 3 d between snow cover depletion on uplands and ponding in depressions demonstrated the role of a shallow subsurface transmission pathway or interflow through frozen soil in routing snowmelt from uplands to depressions. At all sites, depression-focused infiltration and recharge began before complete ground thaw and a significant portion (45 %–100 %) occurred while the ground was partially frozen. Relatively rapid infiltration rates and non-sequential soil moisture and groundwater responses, observed prior to ground thaw, indicated preferential flow through frozen soils. The preferential flow dynamics are attributed to macropore networks within the grassland soils, which allow infiltrated meltwater to bypass portions of the frozen soil matrix and facilitate both the lateral transport of meltwater between topographic positions and groundwater recharge through frozen ground. Both of these flow paths may facilitate preferential mass transport to groundwater.

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Effects of preferential flow on snowmelt partitioning and groundwater recharge in frozen soils

10.5194/hess-2019-169 ◽

2019 ◽

Author(s):

Aaron A. Mohammed ◽

Igor Pavlovskii ◽

Edwin E. Cey ◽

Masaki Hayashi

Keyword(s):

Soil Moisture ◽

Groundwater Recharge ◽

Preferential Flow ◽

Frozen Soil ◽

Time Lags ◽

Runoff Generation ◽

Frozen Ground ◽

Soil Matrix ◽

Frozen Soils ◽

Flow Through

Abstract. Snowmelt is a major source of groundwater recharge in cold regions. Throughout many landscapes snowmelt occurs when ground is still frozen, thus frozen soil processes play an important role in snowmelt routing, and, by extension, on the timing and magnitude of recharge. This study investigated the vadose zone dynamics governing snowmelt infiltration and groundwater recharge at three grassland sites in the Canadian Prairies over the winter and spring of 2017. The region is characterised by numerous topographic depressions where ponding of snowmelt runoff results in focused infiltration and recharge. Water balance estimates showed infiltration was the dominant sink (35–85 %) of snowmelt under uplands (i.e. areas outside depressions), even when ground was frozen, with soil moisture responses indicating flow through the frozen layer. Refreezing of infiltrated meltwater during winter melt events enhanced runoff generation in subsequent melt events. At one site, time lags of up to 3 days between snowcover depletion on uplands and ponding in depressions demonstrated the role of shallow subsurface flow through frozen soil in routing snowmelt to depressions. At all sites, depression-focused infiltration and recharge began before ground thaw and a significant portion (45–100 %) occurred while the ground was partially frozen. Relatively rapid infiltration rates and non-sequential soil moisture and groundwater responses, observed prior to ground thaw, indicated preferential flow through frozen soils. The preferential flow dynamics are attributed to macropore networks within the grassland soils, which allow infiltrated meltwater to bypass portions of the frozen soil matrix and facilitate both lateral transport of meltwater between topographic positions and groundwater recharge through frozen ground. Both of these flowpaths may facilitate preferential mass transport to groundwater.

Download Full-text