How green roofs can help prevent flooding
One very important benefit of green roofs is the ability to slow down and reduce storm water runoff – especially useful in cities and built up areas.
Conventionally, removing excess rainwater has been done by underground pipe systems. These systems are designed to transmit water away as quickly as possible to try and prevent localised flooding. However, as development across the country increases, these systems are becoming more overloaded, creating the potential for flooding. Unfortunately, this is something we are starting to see more and more of.
Climate change means that unfortunately the intensity of rainfall is increasing all over our planet. Sewage systems are increasingly incapable of dealing with these large volumes of rainwater, meaning we’re going to have to think of alternative solutions to deal with this. Research shows that a green roof can significantly reduce the amount of water that flows into sewers, even by as much as 70-95% in the summer.
Because rooftops and streets are hard surfaces, the volume and velocity of rainwater runoff increases tremendously, becoming one of the major sources of flooding and pollution. Because of the nonporous surfaces like pavement and rooftops, a typical section of a city generates five times more runoff than a woodland area of the same size. Green roofs work in the same way by absorbing excess rainwater, and in turn significantly lowering the risk of flash flooding and sewer overflows.