Author
Flerchinger, Gerald | |
Lehrsch, Gary | |
McCool, Donald |
Submitted to: Encyclopedia of Soils in the Environment
Publication Type: Book / Chapter Publication Acceptance Date: 11/11/2003 Publication Date: 10/27/2004 Citation: Flerchinger, G.N., Lehrsch, G.A. and McCool, D.K. 2005. Freezing and thawing processes. In: D. Hillel (ed) Encyclopedia of soils in the environment. Elsevier Ltd. Oxford. U.K. (2):104-110. Interpretive Summary: Seasonally frozen soil strongly influences runoff and erosion on large areas of land around the world. In many areas, rain or snowmelt on seasonally frozen soil is the single leading cause of severe runoff and erosion events. As soils freeze, ice blocks the soil pores, greatly diminishing its capacity for infiltration of water into the soil. This is aggravated by the tendency of water to move to the freezing front, causing elevated ice content and frost heave. Soil freezing and thawing also plays a role in a variety of other environmental processes. This paper presents an overview of freezing and thawing processes within the soil, its effect on hydrology, and its interaction with the environment. Topics discussed include the effect of soil freezing on moisture movement, frost heave, infiltration, erosion, and solute/contaminant movement. Examples are given illustrating the influence of soil type on the extent of frost heave and ice accumulation as the soil freezes. The paper will be used by students, scientists, and resource managers to gain an appreciation of the influence of soil freezing on its environment. Technical Abstract: Seasonally frozen soil strongly influences runoff and erosion on large areas of land around the world. In many areas, rain or snowmelt on seasonally frozen soil is the single leading cause of severe runoff and erosion events. As soils freeze, ice blocks the soil pores, greatly diminishing the permeability of the soil. This is aggravated by the tendency of water to migrate to the freezing front, causing elevated ice content and frost heave. Soil freezing and thawing also plays a role in a variety of other environmental processes. Frost heave poses significant problems for structures, roads, and plant roots. Soil freezing and thawing can create stress fractures and alter soil physical properties including pore continuity and aggregate stability; these alterations can influence soil hydraulic properties and erodibility long after the soil is thawed. Water migration associated with soil freezing can strongly influence solute movement. This paper presents an overview of freezing and thawing processes within the soil, its effect on hydrology, and its interaction with environmental conditions. Topics discussed include the effect of soil freezing on moisture movement, frost heave, infiltration, erodibility, aggregate stabilty, and solute movement. Examples are given illustrating the influence of soil texture on soil freezing dynamics. |