Stormwater Management - Green Roofs Play a Part

The concept of using green roofs has more been around overall city heat mitigation, reduced heat absorption on concrete roofs, more oxygen in the city, even reuse of waste water.

Recent work has indicated that the 'green roof" may be significant in stormwater management, a slightly different outcome than was expected.

While Australia and many other regions do not have a single stormwater and sewer pipe system, some cities do. There the collection of stormwater on green roofs appears to greatly reduce the amount of stormwater entering the sewer system, and thus reduces the potential overflow, quite a problem for these types of systems.

In the areas with separate storm water and sewer disposal systems, it would seem that the collection of especially higher intensity storm rain, the event that often overloads streets and stormwater disposal designs, would also be enhanced, and less stormwater would flow through the system. And, even if it was partially reduced, it would most likely time shift and reduce the major flows, after the rain had flowed down through the green roof and then out down a drainpipe to the ground. The green roof would also assist with removal of pollutants, often in the rain in cities.

More details of the study here -http://www.enn.com/top_stories/article/42701

Green roofs lend themselves well to regions with some regular rainfall, year round. Has not been much development here in the NT, due to our very strongly seasonal rainfall - wet for half the year, generally totally dry for the other half, so plants require watering then.

There is a good example of a green roof in Singapore, at the Botanical Gardens. It seems to work well.