Estimation of Transport Hydraulic Parameters in a Loessic Sediment, Argentina, Application of Column Tests.

MASCIOLI S., BENAVENTE M., MARTÍNEZ D.E.

HYDROGEOLOGY JOURNAL

SPRINGER

Lugar: Berlin Heidelberg; Año: 2005 vol. 13 p. 849 - 857

1431-2174

Dispersivity and porosity parameters necessary for flow and non-reactive transport simulation were calculated and validated for loess-like sediments of the Pampean aquifer located in southeastern Buenos Aires province, Argentina, using infiltration experiments in laboratory columns filled with the selected undisturbed sediment. To obtain parameter values, the experimental curves of arrival of the conservative element chloride were visually adjusted to the curves obtained from numerical simulation using PHREEQC 2.0. Visual adjustment consisted of trying different parameter values until the most representative one was obtained. The best adjustment was reached with dispersivity and porosity values of 0.01 m and 0.35, respectively. Since the analytical solution of flow and transport equations is applicable in simplified cases such as this; it was also opted to adjust parameters automatically, using a model based on this type of solution. The analytical solution was developed using a Fortran programming language; and parameter automatic calibration was programmed minimizing the distance as a function of two parameters. The values obtained were 0.0084 m and 0.39 for dispersivity and porosity, respectively. The sediments studied here constitute the uppermost unit of the Pampean aquifer. Given the relevance of this layer and the growing anthropic influence exercised on it, parameter quantification becomes important both for laboratory tests and for hydrogeochemical simulations oriented toward the study of contaminant transport.