Green Roof Stormwater Runoff

Green roofs can significantly reduce the amount of rain water that would otherwise run off an impervious roof surface.

Green roof stormwater runoff.

Green roofs have a layer of plant material that absorbs water like a sponge. Their major drawback is the initial cost. A typical extensive green roof of 3 5 inches depth will reduce the volume of runoff by about 55 in central pennsylvania and attenuate the peak runoff rates to the level of the pre development land use. Green roofs are very effective stormwater bmps.

Stormwater runoff that comes from downspouts rushes onto roads picking up copper from brake pads fuel and chemicals. Green roofs aim to help eliminate excess stormwater. Green roofs can help to reduce both storm water volume rate of run off entering the drainage system. Therefore green roofs have an important role to play in the urban realm.

Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems.