Traditional materials used to pave our roads and parking lots absorb more solar radiation than vegetated surfaces resulting in enhanced warming in the built environment. Materials such as asphalt also increase the imperviousness of land surfaces, resulting in increased volumes and rates of stormwater runoff, increased accumulation and distribution of warm polluted water and increased erosion. Climate change is likely to amplify these impacts as future climate projections suggest increases in temperature, precipitation and the frequency of heatwaves and extreme precipitation events.
Various stormwater best management practices have been devised to mitigate these impacts utilizing one or a combination of different treatment processes, such as sedimentation, filtration, infiltration, and bio-degradation. Permeable pavements are unique in that they replace existing hard surfaces. Therefore, they do not require additional space that is either unavailable (e.g. in older developments) or can be alternatively used for greenspace or buildings.
The application of permeable pavement in stormwater management is an example of low impact development (LID), which is meant to mimic natural hydrological processes by increasing infiltration, groundwater recharge and lower surface runoff volumes and flow rates that cause damage to both the natural and built environment.
The main environmental benefits of permeable pavements are:
- Reduction of runoff, which reduces flood risk, stream erosion and damage to downstream infrastructure;
- Removal of contaminants from infiltrated stormwater; and
- Reduction in heat flux from the pavement surface to the atmosphere, which helps to mitigate against the urban heat island effect under a warming climate.