Comparison of permeability from laboratory and mini-disk infiltrometer tests

Abstract

To compare the hydraulic conductivity of near surface soils using in-situ field measurement and laboratory measurement, 10 sites on the NTU campus were investigated. First, two in-situ field measurements using mini-disk infiltrometer were performed at each site, one using the standard measurement of unsaturated hydraulic conductivity, another using the modified setup to conduct 1D infiltration test by installing a PVC tube vertically to restrict water flow to solely in the vertical direction. Second, undisturbed soil samples were sampled at the field measurement locations for laboratory falling-head test, grain-size distribution analysis. The grain size distribution analysis includes which includes wet sieving, dry sieving, specific gravity analysis and hydrometer test to identify the soil texture according to the USDA soil classification. The soil texture is needed for interpretation of the mini-disk infiltrometer test. The water content of the soils before and after each experiment were also measured. The modified mini-disk infiltrometer tests were analysed using Hydrus 1D software. Sensitivity analyses were conducted by adjusting the saturated hydraulic conductivity and van Genuchten water-retention parameters of the soil to gain a better understanding of the hydraulic conductivity at each site and between sites.