Sensitivity analysis of transport modeling in a fractured gneiss aquifer

• Coupled groundwater flow and solute transport model in a fractured a gneiss aquifer.
• A double-porosity approach is used to simulate the solute transport.
• UCODE 2013 is used for inverse modeling.
• Inverse modeling of contaminant transport to explore the interaction between model parameters.
• UCODE2013 proved to be a robust and efficient to calibrate solute transport model.

Modeling solute transport in fractured aquifers is still challenging for scientists and engineers. Tracer tests are a powerful tool to investigate fractured aquifers with complex geometry and variable heterogeneity. This research focuses on obtaining hydraulic and transport parameters from an experimental site with several wells. At the site, a tracer test with NaCl was performed under natural gradient conditions. Observed concentrations of tracer test were used to calibrate a conservative solute transport model by inverse modeling based on UCODE2013, MODFLOW, and MT3DMS. In addition, several statistics are employed for sensitivity analysis. Sensitivity analysis results indicate that hydraulic conductivity and immobile porosity play important role in the late arrive for breakthrough curve. The results proved that the calibrated model fits well with the observed data set.