Temperature effects on seepage in vegetated soil cover

The decomposition of municipal solid waste released heat energy, leading to temperature increase in vegetated soil covers and thus changed and even deteriorated the function of rainwater regulation of landfill soil covers at municipal solid waste landfills. To investigate rainfall infiltration in vegetated soil covers under temperature effects, we developed an automatic, multi-point temperature-control system for soil-column tests. Temperature-controlled soil-column model tests were then conducted under rainfall conditions. Using the nonisothermal soil–water retention curve model for rooted soils, we conducted finite-element simulations of nonisothermal seepage in vegetated soil covers through secondary development of COMSOL. Test results and numerical simulations are well consistent and show that temperature significantly affects the spatiotemporal distribution of soil water content. Higher temperature caused deeper positions of wetting front and peak water content as well as reduction in water content of surface layer in vegetated soil covers of municipal solid waste landfills. Derived from the nonisothermal soil water retention curve model of rooted soils, the numerical model of vegetated soil covers shows satisfactory usability and predictability. Ignoring the temperature effect likely induces misleading prediction of leachate pollution and landfill stability in municipal solid waste landfills. This study provides references for the hydraulic-thermal coupling analysis and design of vegetated soil covers for municipal solid waste landfills.