Solute Transport due to Moisture and Temperature Movement within Unsaturated Soil

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Laboratory tests were carried out under applying heat to the top of the sand column. Comparisons between a nonheating and heating columns showed conspicuous difference in solute concentration of chloride ion. Large values of the concentration was obtained from the heating column, especially at the surface. Degree of saturation was not different among each column. The main reason for this difference is vapor movement and heat transfer due to the heating at the surface.The effect of precipitation was also checked using a heating and nonheating sand column. In the nonheating column, concentration decreased due to convection of vertically downward flow of pore water, on the other hand, concentration once exceeded the initial value in heating column. Exact reason was not cleared out, but this result implies the importance of weather conditions for solute transport near the ground surface.Solute transport model was developed reflecting vapor and pore water movement and heat transport. Numerical examples were demonstrated to show the efficiency of the model. The application to the laboratory tests showed a good agreement between the model and the test results. Some improvements were also indicated from these computations. Numerical method for the convection terms in heat and solute transport should be improved considering the Lagrangian scheme. Estimation of evaporation rate should be exactly made from the laboratory tests.