In order to clarify the mechanism of solute migration in an unsaturated zone of soil stratum, the basic experiments on the upward and downward movements of water and solutes (NaCl, Sr, Co, Cs) under the artificial environment (rainfall-evaporation cycles) were carried out. The experimental apparatus used in this study consists of a large soil box, nozzles of rain-fall, infrared lamps, thermometer sensors, recorders and sampling tubes. The vertical profiles of solute concentration, temparature and water content in the unsaturated zone above the groundwater are measured for different groundwater depth. The analytical solutions of governing equations at the steady-state are derived. The comparison between solutions and experimental results shows a good agreement. The results describe that the solute migration depends upon not only vertical movement of moisture but also a depth of capillary fringe.
