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Unsaturated Hydraulic Conductivity Measured by Time Domain Reflectometry Under a Rainfall Simulator
Author(s) -
Parkin Gary W.,
Kachanoski R. Gary,
Elrick David E.,
Gibson Richard G.
Publication year - 1995
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/94wr02535
Subject(s) - ponding , infiltration (hvac) , hydraulic conductivity , reflectometry , soil science , environmental science , hydrology (agriculture) , soil water , time domain , geology , geotechnical engineering , materials science , drainage , computer science , computer vision , ecology , composite material , biology
We used time domain reflectometry (TDR) probes installed vertically at the soil surface beneath a constant‐rate rainfall simulator to measure cumulative water storage and the soil's unsaturated hydraulic conductivity. The slope from linear regression of water storage on time before any applied water infiltrates to the bottom of the TDR probe gives an estimate of the local infiltration rate. Local infiltration rates measured by TDR in the field were plotted against the corresponding local steady state water contents to give an estimate of the soil's unsaturated hydraulic conductivity over a range in water content of 20% using only two applied rainfall rates. The spatial variability in local infiltration rates may be the result of infrequent high‐intensity pulses of rainfall leading to temporary ponding and redistribution of water at the soil surface. Nonlinear optimization was used to estimate the saturated hydraulic conductivity and inverse capillary length scale from TDR data.