On the Soil Moisture Characteristic Curve of Sandy Soil and Its Temperature Dependence

The soil moisture characteristic curves of sandy soils were determined by using the soil column method and their temperature dependence was examined. An analytical expression fitting the observed data is: Sℯ＝1/{1+(αh)ⁿ} m where Sℯ is the effective saturation，h is the matric suction head，and α，m，n are the parameters to be determined experimentally. The temperature coefficient of matric suction，which was calculated from the experimentally determined expression，greatly exceeded the values expected from the c1assical surface tension-temperature relationship. Larger values of temperature coefficient were obtained in decomposed granite in comparison to dune sand. The trapped air in the unsaturated soi1 system was considered to have resulted in the discrepancy between the observed and calculated temperature coefficients