Desalination and Water Treatment | 2019
Assessment of hydrologic and environmental performances of green roof system for improving urban water circulation
Abstract
This study was conducted to assess the applicability of green roofs as a low impact development (LID) technology to reduce storm water runoff volume and nonpoint source pollutants. Specifically, the water cycle effects and pollutant removal efficiency through six monitoring results were analyzed. Based on the results, the green roof system achieved an average runoff discharge rate of 72% for storage, exhibiting a rainfall outflow reduction rate of about six times greater than that of the ordinary concrete rooftop. The average reduction efficiency of pollutants was 77%, 43%, 74%, 57%, and 43% for TSS, BOD, TOC, TN, and TP, respectively. In addition, the reduction efficiencies for heavy metals, including Cu and Zn, and isomers such as n-H were all greater than 72%. However, this removal efficiency was highly dependent on rainfall, which was observed specifically for nutrients, including TN and TP, which showed a negative removal for a 40 mm rainfall. Therefore, it seems to be better when the green roof system was installed with LID technologies such as infiltration trenches, rain gardens, infiltration planters, and other infiltration facilities.