J. Jpn. Soc. Soil Phys.
No. +*2, p. +++1 ,**2§ ¨ © ª*
Field Determination of Soil Hydraulic Properties by Using Soil Water Content
Measured from Dielectric Properties of Unsaturated Soils
Yuji TAKESHITA** Graduate School of Environmental Science, Okayama University,+ῌ+, Naka --chome, Tsushima, Okayama, 1**ῌ2/-*, JapanAbstract
Some new ﬁeld techniques for measuring unsaturated soil hydraulic properties by using soil
water content measured from dielectric properties of unsaturated soils are proposed.

Firstlyin-situ permeability tests for unsaturated soils are developed. The constant head inﬁltration test
and the gravity drainage test were performed continuously. The transient soil water content
data during these tests were measured by a portable soil moisture device.

The vertical soil

moisture proﬁles during the drainage test were used to determine the unsaturated hydraulicconductivity. The inverse solution of unsaturated soil hydraulic functions was applied toindependently measured transient water content for wetting and drying process to consider
hysteresis phenomenon of unsaturated soil hydraulic properties.

Secondly surface ground-penetrating radar (GPR) system is employed to estimate the average soil water content proﬁles inthe survey region as a function of the dielectric constant measured by electromagnetic wave
velocities. GPR o#ers a simple and nondestructive approach for in-situ determination of soil
water content. The utilities of proposed methods are demonstrated by using ﬁeld experimental
data for unsaturated dune sands.
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ﬁltration from a single ring : I. Analysis of steadyﬂow, Soil Sci. Soc. of Am. J., /. : +,--῍+,.+.

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penetrating radar, John Wiley & Sons, pp. 02,῍῏111.

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ductivity values from moisture yield and tension$ +1  3.4$ +2  'P@QR ST

measurements on soil columns, Soil Sci. Soc. Am.

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