Building water sensitive urban design: modelling of green roof

This project evaluates green roofs as a stormwater management tool. The goal of the project is to develop a computer aided stormwater model incorporating green roof, and evaluate its effectiveness. Specifically, the influence of media type, media depth, duration of rainfall event and average reoccurrence interval are investigated in design rainfall. The finalised model is then validated based on observed rainfall for the months of January and February of 2014. Results indicate that the green roofs are capable of removing 73.5% and 86.9% of the monthly rainfall volumes for January and February 2014, respectively, from a roof through retention. Water retention by green roofs effectively increases the time to reach the peak runoff, and slows the peak flows for a watershed. There are seasonal considerations as more runoff is generated during the month of January (northeast monsoon season) compared with the month of February (normal weather). Green roof is also effective in retaining 100% of several storms of less than 10 mm. The results demonstrate that the proposed extensive green roof for the study area functions as an excellent bio-retention system for stormwater control. The results of this research are in tandem with those of other researches performed throughout the world on hydrologic characteristics of green roof