Abstract: Based on grid sample method (20 m×20 m), spatial heterogeneity and distribution of soil water physical properties from 0 to 5 cm of the coal gangue pile in arid desert area were explored by using classical statistics and geostatistics methods. The results showed that the variation of soil bulk density, capillary porosity, capillary maximum moisture capacity, total porosity and saturated moisture contents were weak, while water content showed a moderate variation. The best fitting model of soil bulk density was Gaussian model, and exponential model was the best fitting model for other indices. The C₀/(C₀+C) values of soil bulk density and water content were low and had strong spatial autocorrelation. The capillary porosity, capillary maximum moisture capacity, total porosity and soil saturated moisture showed moderate spatial autocorrelation. Soil bulk density was negatively correlated with capillary porosity, capillary maximum moisture capacity, total porosity and water content, whereas there was no significant correlation between soil moisture content and other indices. Soil capillary porosity, capillary maximum moisture capacity, total porosity, and saturated water content showed a significant synergistic effect between each other. On Kriging contour maps, capillary porosity, capillary maximum moisture capacity, total porosity and saturated moisture had a similar spatial pattern, with high values on the middle and the left side of the lower slope, whereas soil bulk density showed an opposite pattern. Soil water content was mainly affected by the slope position and increased from the upper slope to the lower slope. Our results suggested that land preparation measures should be taken to loosen the soil in root area over the coal gangue pile in arid desert area during vegetation restoration. Moreover, irrigation amount should be properly increased on the upper slope during the initial stage of vegetation restoration, which could improve soil moisture status in the overlying soil area of coal gangue and create uniform and suitable soil water physical conditions for vegetation restoration.

Key words: soil water physical property, spatial heterogeneity, coal gangue pile, geostatistics, arid desert area