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Measurement of Hydraulic Conductivity of Unsaturated Soils with Thermocouple Psychrometers
Author(s) -
Daniel David E.
Publication year - 1982
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1982.03615995004600060001x
Subject(s) - hygrometer , thermocouple , hydraulic conductivity , water content , soil water , soil science , environmental science , saturation (graph theory) , degree of saturation , pedotransfer function , water retention curve , moisture , hydrology (agriculture) , materials science , geology , geotechnical engineering , humidity , composite material , mathematics , thermodynamics , combinatorics , physics
A method of measuring the hydraulic conductivity of unsaturated soil using the instantaneous profile method with psychrometric probes to measure water potential is developed and described. Soil is compacted into cylindrical tubes, and the tubes are sealed and instrumented with thermocouple psychrometers. The soil is moistened or dried from one end of the tube. Psychrometers are read periodically. Hydraulic conductivity is computed from the psychrometer readings and the appropriate moisture characteristic curve for the soil and then plotted as a function of water potential, water content, or degree of saturation. Hydraulic conductivities of six soils were measured at water potentials as low as −80 bar. The measured hydraulic conductivities and moisture characteristic curves were used along with the known boundary flux in a computer program to calculate the final water content profiles. Computed and measured final water content profiles agreed tolerably well.