Abstract

The Runoff Reduction on Green Roof: Influence of Different Characteristics
Track: Water, Wastewater, and Stormwater
Authors: Sachiko Kikuchi, Hajime Koshimizu

This study simulated the storm water retention on the green roof systems. Simulations were using a rational formula and calculated a peak runoff volume per each building. To quantify the effect that these systems have on storm water runoff delay and retention, peak runoff was analyzed from three different conditions; the conventional roof, a green roof system with water condition in early rainfall phase, and late rainfall phase. The runoff coefficient, based on Kikuchi's research, 0.30 for the early phase and 0.48 for the late phase were used. Additionally, as the runoff delay time, 25 minutes for the early and 6 minutes for the late were applied. Rain event was assumed 4th July, 2000. Then, we calculated the peak runoff reduction effect of green roofs at the same case study area and indicated the differences the runoff velocity and the total runoff volume with water conditions for the torrential rainfall.