Premium
Calculation of Capillary Conductivity from Pressure Plate Outflow Data
Author(s) -
Gardner W. R.
Publication year - 1956
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/sssaj1956.03615995002000030006x
Subject(s) - outflow , suction , capillary action , conductivity , hydraulic conductivity , mechanics , flow (mathematics) , capillary pressure , soil water , materials science , thermodynamics , chemistry , geology , physics , porous medium , soil science , porosity , composite material , meteorology
The flow equation describing the movement of water out of a soil sample in the pressure plate apparatus has been solved for a special case. It is assumed that during the outflow process (a) the capillary conductivity is approximately constant, and (b) the relation between the water content and the suction is linear. Both of these conditions can be met if the pressure increment which causes the outflow is made sufficiently small. By measuring the outflow from the sample as a function of time and using the solution of the flow equation, the capillary conductivity can be calculated for each suction interval. Conductivity measurements on three soils indicate that the conductivity decreases approximately as the inverse square to cube of the suction. By using the pressure membrane apparatus, the range of suction over which measurements were made was extended up to 15 bars.