Solute transport through unsaturated soil due to evaporation

A new method for predicting upward solute movement in unsaturated sand soil due to evaporation is developed and tested. Laboratory experiments were conducted in an unsaturated uniformly packed sand column with a cross section of 1.20 X 0.50 m(2) and a constant shallow ground-water table. Evaporation was measured by a new ventilated chamber system. Solute movement from the ground water upward was monitored, Water and solute movement could be accurately reproduced by numerically solving Richards' equation and the convection-dispersion equation in one-dimension. The experimentally measured dispersivity for the unsaturated homogeneous sand agreed closely with the values which are available in the literature. This paper offers a new approach for investigating dispersion phenomena in unsaturated porous media exposed to evaporation.