Comparison of saturated hydraulic conductivity estimated by three different methods

This study compares saturated hydraulic conductivities (K_s) of three sandy soils such as coarse, medium and fine sand. The K_s was obtained using three different methods: empirical methods based on the grain size analysis, the relative effective porosity model (REPM), and breakthrough curve analyses based on tracer tests. Column drainage tests were performed to characterize the water retention properties of the samples, which are required in the REPM. Bench scale tracer tests with various conditions were conducted to obtain reasonable linear velocities of the samples using breakthrough curve analyses and then K_s was estimated using Darcy's law. For the REPM, the differences of K_s for the coarse and fine sand soils were less than one order of magnitude; however, the difference of K_s values between the empirical methods and the breakthrough curve analyses was larger than one order of magnitude. The comparison results suggest that the REPM can be a reliable method for estimating K_s for soil grains, and is cost effective due to its experimental simplicity.