WPŁYW NIEJEDNORODNOŚCI POLA PRĘDKOŚCI NA DYSPERSJĘ HYDRODYNAMICZNĄ W NIENASYCONYM OŚRODKU GRUNTOWYM: BADANIA EKSPERYMENTALNE I MODELOWANIE NUMERYCZNE

Abstract

INFLUENCE OF THE NON-UNIFORMITY OF THE VELOCITY FIELD ON HYDRODYNAMIC DISPERSION IN UNSATURATED SOILS: COLUMN EXPERIMENTS AND NUMERICAL MODELLINGThis work concerns the phenomenon of macrodispersion, i.e. large-scale dispersion effect, caused by the local-scale variability of the flow velocity field, which can exist even in apparently homogeneous natural soils. Experiments were performed on macroscopically homogeneous soil columns of three different lengths with steady-state downward unsaturated flow. The water content in the columns was measured using the radiometric method while the tracer concentration was measured at the outflow using the conductometric method. The numerical model was applied to describe mass transport in the columns. The stochastic model of solute transport based on the assumption that the water flows by paths, with no mass exchange between the adjacent paths, but also it accounts for the possible mass exchange between the paths.