Solute Dispersion in Porous Media at different transport velocities and distances

Dispersion is a key process controlling transport of solutes in porous media. The aim of this paper is to analyse and compare the scaling behavior of the hydro-dispersion for some different sandy soils by means of tracer tests. For each considered porous medium, breakthrough curves were measured at different transport distances and water velocities. Successively, using the measured breakthrough curves, hydrodispersion parameters were estimated for each sandy soil and for each transport distances and water velocities. Specifically, estimated longitudinal dispersivity of each sandy soil has been compared respect to the transport distance and Darcy velocity. The results show that the longitudinal dispersivity increased with increasing transport distance and with the Darcy's velocity, for all analysed porous media, in agreement with existing observations. Moreover, the variation of dispersivity respect to the scale of measurement seems to be related to the total porosity of porous media, while the variation against Darcy velocity follows the grains size of the analysed sandy soils.