Field techniques for measuring soil hydraulic properties in unsaturated soils

In-situ permeability tests using soil water contents that easily and quickly measure the saturated-unsaturated hydraulic properties in the unsaturated soils are proposed. The continuous constant head infiltration test and gravity drainage test with intrusive soil moisture device to measure the field-saturated hydraulic conductivity and the field-saturated volumetric water content were performed. The unsaturated soil hydraulic properties were estimated by transient soil water contents during these tests. Sensitivity analysis was carried out under the estimation parameters are limited. The change of the water content in the soil during the constant head infiltration test process and the gravity drainage test process were individually simulated by the seepage flow analysis. From these simulations, functional model of the unsaturated soil hydraulic properties considering the hysteresis phenomenon were identified.