Abstract:Based on one-dimensional vertical infiltration experiments, we studied the effects of thickness of gravel (0, 3, 6, 9, 12 cm) on water infiltration and redistribution in water repellent soils with constant bulk density, and the infiltration process were simulated using different models. The results showed that the migration distance of the wetting fronts were increased significantly (p<0.05). Within the same period, all the cumulative infiltrations, which were positively correlated with the thickness of gravel, were higher under gravel covered treatments than that of the control group (p<0.05) in water repellent red soil. Both the stable infiltration rate and initial infiltration rate of the water repellent red soil could be described by exponential function with the thickness of gravel cover, and the coefficients of determination were 0.91 and 0.87 respectively. Compared with the control group, the gravel cover increased the stable infiltration rate and initial infiltration rate of water repellent tidal soil, the stable infiltration rate had a quadratic relationship with the thickness of gravel, the coefficient of determination was 0.78. The stable infiltration rate reached the maximum when the thickness of gravel was 6 cm. The water content in the section of water repellent soils was increased, with the largest increases of 180.8% and 57.6% respectively in red soil and tidal soil. Under the condition of isolated evaporation, the water contents of the upper layer in the water repellent soil under different thicknesses of gravel cover (above the wetting front) showed:stop infiltration > redistributed for 1 day > redistributed for 3 days > redistributed for 7 days. Horton infiltration model had the best fitting effect on water repellent soil infiltration under gravel cover, which made it suitable to analyze and predict the infiltration process in water repellent soils under gravel cover.