Abstract
At the high density urban area where the urban type flood is common, it is difficult to construct a newer rainwater storage and infiltration plants in economically and spatially. As a strategy of saving water volume control, we focused on the storage effect of green roof. It is considered of value for torrential rain countermeasure, such as greening the unused roofs, rooftop terraces and ensuring the saving water volume. In this study, the purpose was to clarify the effictivity of storage-drain boards of green roof for a torrential rain. The obtained results are followings: 1.The storage-drain boards of green roof with a large surface area of two sides are able to delay rainfall runoff. The green roof panel with the largest surface area delayed the rainfall runoff about 1.5 times in runoff velocity. 2.The larger the runoff ratio grows, the more quickly the runoff velocity becomes. Runoff ratio has a relationship with relief structure of the storage-drain boards of green roof.
