Estimation of Soil Solute Transport Parameters Using Small-Core Displacement Experiments Coupled with HYDRUS-1D Inverse Modeling: Technical description

Abstract

Accurate estimation of soil solute transport parameters is essential for predicting nutrient leaching and contaminant migration in agricultural and environmental systems. This study presents an integrated methodology combining laboratory displacement experiments on small soil cores with inverse modeling using HYDRUS-1D. Conservative tracer breakthrough curves were obtained under saturated steady-state flow conditions. Transport parameters were initially approximated using analytical solutions of the convection–dispersion equation and subsequently refined through inverse optimization. The inverse method simultaneously estimated longitudinal dispersivity and pore water velocity by minimizing discrepancies between observed and simulated concentrations. The results showed that inverse modeling significantly improved parameter accuracy and reduced uncertainty in comparison with analytical fitting. The proposed approach provides a robust and reliable framework for laboratory-based characterization of soil solute transport suitable for predictive modeling and environmental risk assessment.