Frozen soil infiltration widely occurs in hydrological processessuch as seasonal soil freezing and thawing, snowmelt infiltration, andrunoff. Accurate measurement and simulation of parameters related to frozensoil infiltration processes are highly important for agricultural watermanagement, environmental issues, and engineering problems in cold regions.Temperature changes cause soil pore size distribution variations andconsequently dynamic infiltration capacity changes during differentfreeze–thaw periods. To better understand these complex processes and toreveal the freeze–thaw action effects on soil pore distribution andinfiltration capacity, black soils, meadow soils, and chernozem were selectedas test subjects. These soil types account for the largest arable land areain Heilongjiang Province, China. Laboratory tests of soils at differenttemperatures were conducted using a tension infiltrometer and ethyleneglycol aqueous solution. The stable infiltration rate and hydraulicconductivity were measured, and the soil pore distribution was calculated.The results indicated that for the different soil types, macropores, whichconstituted approximately 0.1 % to 0.2 % of the soil volume underunfrozen conditions, contributed approximately 50 % of the saturated flow, and after soil freezing, the soil macropore proportion decreased to 0.05 % to 0.1 %, while the saturated flow proportion decreased to approximately30 %. Soil moisture froze into ice crystals inside relatively large pores,resulting in numerous smaller-sized pores, which reduced the number ofmacropores but increased the number of smaller-sized mesopores, so that thefrozen soil infiltration capacity was no longer solely dependent on themacropores. After the ice crystals had melted, more pores were formed withinthe soil, enhancing the soil permeability.
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