Hydrologic performance of permeable pavements under extreme and regular rainfall conditions

Permeable pavement (PP) provides stormwater infiltration at source through permeable surface without occupying extra space and receives lots of attention in research and engineering applications worldwide. However, the hydrologic performance of PP under extreme and regular rainfall conditions and their differences have not been well understood, especially through field experiments. This study quantified the runoff mitigation and retention capacity of seven types of PP under different rainfall conditions using artificial rainfall experiments and field monitoring. The results showed that most PP tested in this study generally exhibited good hydrologic performance during extreme and regular rainfall events when they were newly constructed (runoff peak reduction >= 52 %). However, porous blocks showed a significant decay in runoff peak reduction (>= 40 %) after one year of service. Grass cover, resin bound surface, and permeable interlock concrete paver panels performed the best without detectable performance decay. The hydrologic performance of PP can vary in response to different rainfall conditions due to the variation in rainfall-runoff generation mechanisms. Infiltration excess runoff (i.e., permeability of surface layer lower than rainfall input) dominates in events high in intensity and short in duration, while saturation excess runoff (i.e., PP subbase filled up with water) dominates in events low in intensity and long in duration. Based on the mechanisms, the dominant factors that govern the hydrologic performance of PP under different rainfall conditions can be further concisely identified.