Abstract: In order to reveal the effect of amount of water-retaining agent on the two-dimensional infiltration of water into soils with and without sand cover, this study took a bare soil test group for comparison, the effects of different water-retaining agent dosage (0, 0.1%, 0.2%, 0.5%) on soil water infiltration under conditions of sand cover and non-sand cover were studied through a simulated single-point source infiltration experiment. The results show that the regularity of soil water infiltration under the two different conditions is basically the same. In the early stage of infiltration, with the increase of the amount of water-retaining agent, the smaller the infiltration rate is, the greater the cumulative infiltration is. The difference between the horizontal and vertical movement of the wetting front is not significant, while the horizontal and vertical ratio of the wetting body is not significant as well. The infiltration rate and cumulative infiltration in the middle stage of infiltration are consistent with those in the initial stage of infiltration, but both the horizontal ratio and vertical ratio of the wetting body increase in the horizontal direction and decrease in the vertical direction as a contrast. In the later stage of infiltration, the infiltration rate basically tends to be stable, and the cumulative infiltration continues to increase. The Kostiakov infiltration model can characterize the regularity of two-dimensional infiltration of water into sandy loam by the water-retaining agent.

Key words: infiltration rate, cumulative infiltration, wetting front, aspect ratio, Kostiakov model