Uncertainty in analyses of one-dimensional steady-state seepage through random porous media

The aim of this paper is to assess the propagation of uncertainty in analyses of one-dimensional steady-state flow through random porous media. It is considered that uncertainty originates from lack of precise knowledge of soil hydraulic conductivity. This uncertainty is modelled by means of random variables. Taking into account experimental evidences, it is accepted that hydraulic conductivity has a log-normal probability distribution. The paper focuses on propagation of uncertainty from hydraulic conductivity to the computed flow rate through homogeneous and stratified random materials. The most common techniques available to evaluate propagation of uncertainty are briefly reviewed. The applicability and limitations of these techniques are assessed. Parametric studies to gauge the effect of uncertainty on soil hydraulic conductivity on the output statistics of flow rate are performed. Attenuation of uncertainty on flow rate as the number of materials in stratified soils increases is evaluated. Conclusions are presented regarding this attenuation and the usefulness of the different stochastic techniques employed, which proved to be more complementary than antagonistic.