Fundamental study on migration and accumulation of solute in unsaturated zone of soil column by evaporation

The evaporation from soil surface and solute migration in an unsaturated zone above the groundwater are studied experimentally and theoretically. The experimental apparatus used in this study consists of a wind tube, soil column, groundwater feeding tank and a set of measurement equipments. The vertical profiles of solute concentration, temperature and water content along soil column, and the evaporation rate from soil surface are measured for different wind velocities. The analytical solutions of governing equations at the steady state are developed for solute migration in coupling with heat transport and moisture movement. The comparison between analytical solutions and experimental results shows an excellent agreement. The results describe that the solute migration depends upon not only vertical movement of moisture but also a depth of capillary fringe. (author)