Articles | Volume 21, issue 5
Research article
03 May 2017
Research article |  | 03 May 2017

Hydraulic and transport parameter assessment using column infiltration experiments

Anis Younes, Thierry Mara, Marwan Fahs, Olivier Grunberger, and Philippe Ackerer

Abstract. The quality of statistical calibration of hydraulic and transport soil properties is studied for infiltration experiments in which, over a given period, tracer-contaminated water is injected into an hypothetical column filled with a homogeneous soil. The saturated hydraulic conductivity, the saturated and residual water contents, the Mualem–van Genuchten shape parameters and the longitudinal dispersivity are estimated in a Bayesian framework using the Markov chain Monte Carlo (MCMC) sampler. The impact of the kind of measurement sets (water content, pressure inside the column, cumulative outflow and outlet solute concentration) and that of the solute injection duration is investigated by analyzing the calibrated model parameters and their confidence intervals for different scenarios. The results show that the injection period has a significant effect on the quality of the estimation, in particular, on the posterior uncertainty range of the parameters. All hydraulic and transport parameters of the investigated soil can be well estimated from the experiment using only the outlet concentration and cumulative outflow, which are measured non-intrusively. An improvement of the identifiability of the hydraulic parameters is observed when the pressure data from measurements taken inside the column are also considered in the inversion.

Short summary
The estimation of flow and solute transport in unsaturated soil is essential for quantifying groundwater resources or pollution. Usual column laboratory experiments and a new method are analyzed using a global sensitivity analysis. The data sets are composed of water pressure and water content measured inside the column and water flow rate and solute BTC measured at the outflow. Non-invasive methods (using flow rate and BTC only) provide comparable results than usual invasive methods.