Hydrologic Performance of Distributed LID Stormwater Infrastructure on Land Developments under a Changing Climate: Site-Scale Performance Improvements

Abstract

Traditional land development stormwater management replaces natural pervious surfaces with impervious surfaces such as pavements and buildings. This increases the rate of runoff that is typically then managed through drainage systems and controlled at or near the site discharge location. This approach often leads to increases in total runoff volume, which can lead to higher peak flows in downstream stormwater systems. Low impact development (LID) technologies, such as porous pavements and green roof systems, provide an alternate approach to managing site runoff by mimicking the pervious surfaces they replace. However, these technologies are often used alongside traditional stormwater infrastructure because their entire hydrologic benefit has not been fully explored. Herein we examine the reduction in peak discharge and total runoff volume achieved through the use of porous pavements and green–blue roof systems (a green roof with an underlying storage volume) on three land developments located on the coastal plain of South Carolina. Model results show that the inclusion of green–blue roof systems can significantly reduce peak discharge compared to traditional roof systems and common modular green roof systems, although they have negligible impact on the total volume discharged. Porous pavements significantly reduce total volume discharged, even when placed over low infiltration soils, but have less impact on peak flow depending on their design. The implementation of LID technologies has the potential to improve site performance beyond standard design rainfall depths, indicating that the use of LID may offset the impact of climate change–induced increases in extreme rainfall event depth and intensity.