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ARS Home » Pacific West Area » Boise, Idaho » Northwest Watershed Research Center » Research » Publications at this Location » Publication #174361

Title: Using soil freezing characteristics to model multi-season soil water dynamics

item Flerchinger, Gerald
item Seyfried, Mark
item Hardegree, Stuart

Submitted to: Vadose Zone Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2006
Publication Date: 10/3/2006
Citation: Flerchinger, G.N., Seyfried, M.S., Hardegree, S.P. 2006. Using Soil Freezing Characteristics to Model Multi-Season Soil Water Dynamics. Vadose Zone Journal. 5:1143-1153.

Interpretive Summary: Computer simulation of soil water enables prediction of water movement into and out of the soil profile, including processes of infiltration, runoff, and percolation to groundwater along with transport of any contaminants within the soil water. Soil characteristics describing how much water is retained by the soil is critical to accurate prediction of soil water movement, but these properties are difficult and time consuming to measure. A method was developed to obtain these properties through measurement of soil temperature and liquid water content when the soil is frozen by taking advantage of similarities between drying and freezing relations within the soil. This method will allow more easily measured soil moisture retention characteristics and will enable more accurate simulation of soil water movement, plant water use, infiltration, runoff, and groundwater recharge to address management impacts on water quality and conservation.

Technical Abstract: The soil moisture characteristic relation is critical to accurately simulate soil water dynamics but is difficult and time consuming to measure, particularly for the dry regions of the curve. The relation between freezing soil temperatures, soil water potential and liquid water content, termed the soil freezing characteristic, is controlled by the soil moisture characteristic curve. With the widespread use of time-domain reflectometry to measure liquid water in frozen soil, simultaneous measurement of soil temperature and liquid water content under frozen conditions enables in situ estimation of the soil moisture characteristic curve through its similarity to the soil freezing characteristic. This paper demonstrates the applicability of deducing the soil moisture characteristic curve from in situ measurements of the soil freezing characteristic for simulation of both frozen and unfrozen soil water dynamics. Results suggest that the soil freezing characteristic may be used to estimate the moisture release curve when soil temperature and liquid water content sensors are co-located and measured simultaneously. This methodology is particularly effective for the drier portion of the soil moisture characteristic which is problematic to measure by conventional means.