Abstract: In this paper we aim to enhance the theoretical methods for analyzing surface water infiltration processes by focusing on the distinct characteristics of stagnated and reduced infiltration during the infiltration from high-suction soil to low-suction soil. By considering the unsaturated properties of soil near the wetting front, we divided the water infiltration process into three stages: upper soil infiltration, stagnant water infiltration, and subsoil infiltration. We further derived the surface water infiltration model to refelct the water blocking and infiltration reduction effect in layered soil infiltration, and analyzed the sensitivity of model parameters via comparison with existing experimental results and models. Results demonstrate that the model proposed in this paper provides a more accurate description of water retention and infiltration reduction in layered soil infiltration. It offers a better understanding of the infiltration mechanism. Assuming a linear decrease in infiltration rate during the stagnation of wetting fronts aligns with real-world observations. Different soil properties have varying effects on infiltration: the type, burial depth, and ponding depth of the lower layer of low-suction soil significantly influence the infiltration characteristics. The initial water content of the soil primarily affects the infiltration time. Moreover, the proportion of the wetting front transition zone plays a significant role in water retention.

Key words: layered soil, water infiltration, water blocking and infiltration reduction, wetting front, unsaturated characteristics