Rainfall-runoff relations for porous pavements under artificial rainfall.

Three porous pavement systems were investigated to evaluate their infiltration capability for precipitation. Experiments were conducted to simulate different kinds of porous pavements with different sub-base materials in each of the cells, and the discharge volumes from each cell were monitored. The relationship between rainfall intensity, outflow, and outflow duration was analysed. Because of storage in the sub-base, the infiltration forms subsurface flow in the porous concrete block paving and sub-base, which increases infiltration to the subsurface after rainfall. Results show that all porous pavement treatments increased infiltration and decreased runoff. For all treatments, the optimum thickness of the porous pavement was 31 cm, and consisted of a 6 cm top layer of porous concrete and a 25 cm sub-base (10 cm concrete without sand and 15 cm aggregate base). Under a rainfall rate of 59.36 mm/h, the runoff coefficient of the above treatment was 0, while the coefficient of the impervious pavement was 0.85.