Publication date: 1 October 2017
Source:Geoderma, Volume 303
Author(s): Behzad Ghanbarian, Allen G. Hunt
Accurate estimation of unsaturated hydraulic conductivity K (S w ) in soils has been of great interest to soil physicists and hydrologists in the past several decades. Although various methods such as a “bundle of capillary tubes” conceptual approach were applied in the literature to theoretically model hydraulic conductivity in term of water saturation, in this study we invoke percolation theory, which quantifies the effect of the interconnectivity of pores on the macroscopic fluid flow. We incorporate the pore-solid interface roughness effect in the hydraulic conductance-pore radius (g -r ) relationship, evaluate our K (S w ) model using 104 soil samples from the UNSODA database as well as another 20 soil samples from the Rijtema database, and compare it to the Ghanbarian-Alavijeh and Hunt (2012) model. Generally speaking, we experimentally demonstrate that K (S w ) estimations were improved over the entire range of water saturation when the surface roughness effect was incorporated. However, our model still underestimates the unsaturated hydraulic conductivity at low water saturations (corresponding to K (S w )K (S w ) estimations were improved substantially. Other plausible sources for K (S w ) underestimation are also discussed.
Source:Geoderma, Volume 303
Author(s): Behzad Ghanbarian, Allen G. Hunt