Estimation of the mass transport parameters of aquifers according to data from field tests with a pulse or a continuous source and an arbitrary location of the observation well

Abstract

An identification method for determining the aquifer’s mass transport parameters is proposed, based on data from field tracer tests with a pulse or a continuous source and an arbitrary position of the observation well in respect to the tracer entry point. The method is also applicable in the presence of a representative set of data on changes in the concentration of pollutants at different points in the aquifer around a short-term (instantaneous) or a continuous surface or underground source. The identification procedure is based on the automated comparison of the observations data with a series of theoretical curves by varying the required parameters in order to achieve maximum compliance. The tracer transport is represented by analytical solutions of the partial differential equation for mass transfer in a homogeneous and isotropic two-dimensional porous media. The developed computer programs include numerical optimization using the Levenberg-Marquardt algorithm. Results from tests performed in order to assess reliability and errors of detection and identification are presented. Using the programs, the mass transport parameters: active porosity n0, effective (sorption) porosity nS, longitudinal dispersivity αL, transverse dispersivity αT and rate constant γ can be determined.