Runoff and Infiltration Dynamics on Pervious Paver Surfaces

When natural or agricultural land is converted for (sub)urban or commercial use, the addition of impervious surfaces becomes a dominating factor in the new urban hydrologic regime. To help minimize the negative hydrologic effects of this land use change, urban best management practices (BMPs) are continually being developed. Several BMPs have been developed to allow infiltration on certain transportation surfaces. Among others, these include substituting traditional pavement with pervious pavers. Small gaps between paver blocks typically represent about 10% perviousness by area. It is generally accepted that infiltration is maintained on this portion of the surface, resulting in an overall reduction in runoff discharge, versus a traditional pavement. However, surface sealing resulting from silt or clay particles deposited by water, wind, or vehicles may result in reduction or elimination of infiltration. To test the extent to which this phenomenon can influence runoff and infiltration dynamics, a series of laboratory rainfall simulations was performed on 1.0 x 0.6 x 0.2-m boxes a pervious paver surface located down slope from a soil box representing an erodible soil surface area. Rainfall representing a 5-yr return period storm was simulated and timed runoff and infiltration samples were collected to determine discharge rates of water and sediment from each 1- m long section. Results indicate that almost all of the rainfall and run-on applied to pervious paver surfaces initially infiltrated. However, infiltration rates decreased and runoff rates increased with successive rainfall events, and after 10 to 11 5-yr rainfall events, siltation and surface sealing between paver blocks prevented infiltration from taking place entirely. This indicates employment of pervious paver blocks requires ongoing maintenance to prevent surface silting and sealing for sustained effectiveness.