Predicting Hydraulic Properties from Pressure-Saturation Curves

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Hunt 0609884Pressure-saturation curves reveal information about the pore size distribution in porous media, but interpretation of these data can be complicated through hysteresis and lack of equilibration. Lack of equilibration is often a consequence of low hydraulic conductivity, K, under dry conditions. Low values of K can be predicted within the framework of percolation theory using a general result that as saturation is reduced flow crosses over from pore-size dominated (critical path analysis) to connectivity dominated (percolation scaling). Although this analysis was already performed analytically for a particular form of the pore size distribution (fractal) the proposed work will perform general (numerical) analysis using an arbitrary water retention curve as input. A self-consistent procedure accounts for complications from falling out of equilibrium at low moisture contents. The outputs are the pore-size distribution and the hydraulic conductivity. Supplemental inputs from part icle size distributions will give additional confirmation of the pore size distribution and also be used for calculation of the specific surface area, which is relevant to the critical moisture content for percolation.