UNSATURATED WATER CONDUCTIVITY AND DIFFUSIVITY IN SOIL AGGREGATES

摘要

This paper presents the results of a study on the effect of the soil aggregate sizes of Orthic Podzol and Haplic Phaeozem on the values of coefficients of unsaturated water conductivity and diffusivity. It was found that extreme values of the coefficient of unsaturated water conductivity in Orthic Podzol varied from 0.2 10~3 cm day~(-1) for aggregates of 0.25-0.5 mm to 0.8 10~(-9) cm day~(-1) for aggregates of 5-10 mm, and in Haplic Phaeozem - from 0.2 10~3 cm day~(-1) for aggregates of 0.25-0.5 mm to 0.6 10~(-9) cm day~(-1) for aggregate fractions of 3-5 and 5-10 mm. Extreme values of the water diffusivity coefficient in Orthic Podzol were 0.13 10~6 cm2 day~(-1) for aggregates smaller than 0.25 mm and 0.96 10~(-3) cm~2 day~(-1) for aggregate fraction of 5-10 mm, and in Haplic Phaeozem 0.97 10~5 cm~2 day~(-1) for aggregate fractions of 0.25-0.5 mm and 0.6 10~(-3) cm~2 day~(-1) for aggregates larger than 3 mm. The study showed that the character of the relation of the dynamic water characteristics,i.e. the coefficients of water conductivity and diffusivity, to soil water content and its potential is directly affected by static water characteristics, i.e. the form of the water retention curves of the soils. The study also showed that water movementin the unsaturated zone of the soils is reflected, with good approximation, by both the water conductivity coefficient and the water diffusivity coefficient.