Premium
Measuring Hydraulic Properties Using a Line Source II. Field Test
Author(s) -
Zhang Z.Fred,
Kachanoski R.Gary,
Parkin Gary W.,
Si Bingcheng
Publication year - 2000
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/sssaj2000.6451563x
Subject(s) - permeameter , infiltrometer , hydraulic conductivity , infiltration (hvac) , reflectometry , soil science , line source , tracer , saturation (graph theory) , pressure head , environmental science , vadose zone , hydrology (agriculture) , hydraulic head , soil water , geology , materials science , geotechnical engineering , time domain , optics , mathematics , physics , composite material , combinatorics , computer science , nuclear physics , computer vision , thermodynamics
We designed and tested a field method to measure unsaturated soil hydraulic properties using multi‐purpose time domain reflectometry (TDR) probes below a surface line source with constant flux of water. The surface line source was produced with a moving irrigation system at a field site sheltered from precipitation. Two hundred multi‐purpose TDR probes were vertically installed in the soil beneath the line source to measure soil water pressure head (ψ), water storage ( W ), and tracer travel time ( T ). The soil hydraulic properties, the inverse macroscopic capillary length (α), hydraulic conductivity at saturation ( K s ), and soil water content at saturation (θ s ) were estimated by inverse procedures with new analytical expressions. Five combinations of measurement sets, namely W ‐only, ψ and W , ψ and T , and W and T , and ψ and W and T were used. Approximate confidence contours in the α– K s plane were calculated to show the precision of the parameter estimates. For comparison, hydraulic properties were also measured by means of the Guelph Permeameter (GP) and the modified Guelph Pressure Infiltrometer (GPI) systems. Hydraulic parameters estimated from only W measurements were similar to those estimated from the combinations of W and ψ, or W and T , or W and ψ and T The estimated hydraulic parameters were similar to those obtained with three‐dimensional (3‐D) infiltration measurements by means of the GP and GPI systems.