Analytical Study for Transient Infiltration of Water in Vegetated Landfill Cover under a Time-Varying Rainfall Scenario

Abstract Vegetated landfill covers (VLC) are extensively applied to block rainwater infiltration and reduce the leachate generation. However, the associated analytical works remain limited. This study, for the first time to our best knowledge, develops analytical solutions for transient infiltration of water in the VLC (consisting of rooted and unrooted layers) under a time-varying rainfall scenario, incorporating the natural evaporation effect. Then, key expressions of an analytical solution under several common rainfall patterns are presented. On this basis, the obtained solutions are validated through two comparisons. Finally, the conducted application study finds that, among the five rainfall patterns with equal total rainfall, the “prepeak” rainfall pattern induces the largest cumulative bottom percolation C Q b . An increase in evaporation rate decreases the C Q b , and such effect gradually grows over time. Among different initial water content forms, the form with a larger bottom water content will lead to a larger C Q b , but this impact mainly occurs in the early stage of the rainfall event. For four classic root architectures considered, the VLC is most effective in blocking bottom water percolation with the uniform root architecture, while it is least effective with the exponential root architecture. Further, the VLC’s effectiveness in blocking bottom water percolation has been observed to become stronger with the increase of rooted layer thickness and transpiration rate, and such function is more effective than that of a soil-based landfill cover with no root. Overall, this analytical investigation can take into account the combined effects of time-varying rainfall feature and natural evaporation and contribute to guiding the application and design of VLCs.