Evaluation of some methods for measuring transient hydraulic properties of rain-induced surface seals on two clay soils.
1994
Silburn D.M. | Foley J.L.
Two methods ('post-rain' suction permeameter and rainfall in situ) of measuring seal flux and conductivity under appropriate hydraulic boundary conditions were tested in a laboratory for two clay soils under simulated rain. The suction permeameter tests showed that conductivity of surface seal samples is altered by the suction applied during the measurement. This occurred in the absence of rain and appears to be more general than previously reported. Transient infiltration and conductivity measured by the 2 methods were in close agreement from ponding time onwards, provided suction equal to that measured under the seal was applied in the suction permeameter. The suction permeameter can provide conductivity data under a wide range of conditions than the rainfall in situ method, including prior to ponding, but required measured subseal suction data. Desorption moisture characteristic curves (MCC) and measured subseal moisture content gave useful estimates of subseal suction after commencement of surface ponding, provided: a correction from desorption to adsorption is not made; and MCC are measured using appropriate pre-treatment.
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