Abstract: To study the influence of initial moisture content on soil infiltration characteristics, five different treatments were set up（the corresponding initial moisture contents were 1.5%, 7.5%, 13.5%, 19.5%, and 25.5%）, and indoor soil column experiments were conducted. The infiltration time of each soil column and the amount of water injected every time were recorded. The planning-solving tools were used to determine the parameters of the Kostiakov-Lewis model, Horton model and Philip model. The results showed that: ① When the initial moisture content was constant, the cumulative infiltration volume gradually increased with time, and the infiltration rate gradually decreased. The initial moisture content had a significant effect on the fluctuation of the infiltration rate. ② When the initial moisture content was less than 19.5%, the applicability of the three models was good, whose correlation coefficients of the measured and simulated values were all above 0.99. When the initial moisture content was more than 19.5%, the applicability of the Kostiakov-Lewis model and the Philip model was good, but the Horton model was not so good as them. ③ In the Kostiakov-Lewis model, the fluctuation of infiltration coefficient k with different initial moisture contents was maximal, the stable permeability f₀ was minimum, and infiltration index a was between them. In the Horton model, the fluctuation of the initial infiltration rate i₀ with different initial moisture contents was the most obvious, the stable infiltration rate i_c was the least significant, and the parameter β was between them. In the Philip model, the fluctuation of the soil absorption rate S with different initial moisture contents was bigger, and the stable infiltration rate A was smaller.

Key words: initial moisture content, infiltration characteristics, Kostiakov-Lewis model, Horton model, Philip model