Abstract: Soil permeability,the movement of water into the soil profile,is a key process in the water cycle. Soil permeability coefficient is an important parameter for soil permeability. In order to clarify the acceptability of the one-dimensional horizontal infiltration method(one-D method)for simultaneously determining both the saturated and unsaturated permeability coefficients of aeolian sandy soil in interdune at the southern edge of Gurbantunggut Desert,Xinjiang,China,we carried out indoor soil one-dimensional horizontal infiltration test. The cumulative infiltration(I)and wetting front length(X_f)were measured under different infiltration pressures(0 cm,5 cm,10 cm,20 cm,30 cm,40 cm,50 cm,60 cm). The relationships between I and X_f,I and the square root of time (t^0.5)were also analyzed. The saturated permeability coefficient(K_s)obtained by one-D method and Gardner model was compared with the result obtained by using the TST-55 infiltrometer at fixed head. The results show that there was a significant linear relationship between I and X_f,and it was more reasonable to assume that the average soil moisture content after infiltration was equal to the average increment of moisture content in wet zone than that of Green-Ampt model. There was also a significant linear relationship between I and t^0.5,and the Philip equation could well reflect the characteristics of horizontal infiltration under different infiltration heads. The values of K_S were 1 424.16 mm·d^-1 and 1 156.10 mm·d^-1,determined by using the one-D method and using the TST-55 infiltrometer method under the constant head,respectively. The similar result suggested that it was reliable to obtain the saturated permeability coefficient of aeolian sand soil in interdune using the one-D method. In addition,the value of pore size distribution parameter(α)determined using the one-D method was about 5.71 m^-1 for aeolian sand soil in interdune. According to theK_S and α through the Gardner model,the unsaturated permeability coefficient(K(Ψ))could be subsequently calculated. Compared with the widely-used instantaneous profile method,it was relatively easier and less time-consuming for determining the K(Ψ)of field soil by the one-D method. In conclusion,the one-dimensional horizontal infiltration test for determining permeability coefficient of aeolian sandy soil in interdune at the southern edge of Gurbantunggut Desert is feasible,which can provide both parameters for the hydraulics research and theoretical references for selecting methods on the soil hydrodynamic study in arid land.

Key words: one-dimensional horizontal infiltration, permeability coefficient, cumulative infiltration, wetting front, Gurbantunggut Desert