Optimal hygric material properties and top layer thicknesses for permeable pavements

Permeable pavements potentially offer a double solution to climate change challenges in increasingly urbanized areas. Unlike common pavements, they simultaneously mitigate flooding by higher moisture absorption and abate the urban heat island effect by promoting moisture evaporation, resultantly lowering surface temperatures. However, practical implementation is hindered by a lack of comprehensive knowledge. This study investigates the influence of the hygric material properties and top layer thicknesses of the permeable pavement on rainwater runoff and surface temperature through hygrothermal simulations. Examining the material properties using the Van Genuchten – Mualem expressions and Sobol sequence sampling reveals the primary factors affecting runoff and temperature. Capillary moisture content and capillary permeability significantly impact both outcomes. Complementarily, a weaker correlation between mean pore radius and rainwater runoff is identified. Additionally, modifying the top layer thickness demonstrates its role in reducing runoff and temperature. The study finally also considers various climates, which confirm the general validity of the findings. Ultimately, this research provides valuable insights on the efficacy of permeable pavements in mitigating the risk on flooding and the urban heat island effect, offering guidance for their optimal implementation.