Global sensitivity analysis of groundwater transport

• Contaminant attenuation is a key transport variable dependent on seven parameters.
• Global sensitivity of attenuation addresses significance of parametric uncertainty.
• The uncertainty in macro-dispersion and mass transfer rate appear most significant.

SummaryIn this work we address the model and parametric sensitivity of groundwater transport using the Lagrangian-Stochastic Advection–Reaction (LaSAR) methodology. The ‘attenuation index’ is used as a relevant and convenient measure of the coupled transport mechanisms. The coefficients of variation (CV) for seven uncertain parameters are assumed to be between 0.25 and 3.5, the highest value being for the lower bound of the mass transfer coefficient k0k0. In almost all cases, the uncertainties in the macro-dispersion (CV = 0.35) and in the mass transfer rate k0k0 (CV = 3.5) are most significant. The global sensitivity analysis using Sobol and derivative-based indices yield consistent rankings on the significance of different models and/or parameter ranges. The results presented here are generic however the proposed methodology can be easily adapted to specific conditions where uncertainty ranges in models and/or parameters can be estimated from field and/or laboratory measurements.