Green Infrastructure - there are some traditional, contemporary and evolving synthesized definitions of Green Infrastructure that exist today. However, first; Infrastructure itself may be simply defined as: the delivery of public services; including water, sewage, transportation, utilities, rights of way, parks, etc.
The original definition of Green infrastructure - from the 1990's - pertains more to developments; such as: industrial and commercial parks and larger residential housing projects, etc... wherein Green spaces are preserved, enhanced and/or connected through a series of Hubs, Corridors and Sites, in order to decrease fragmentation for movement of wildlife: mammals, insects, birds, etc... and also to preserve natural hydrologic processes, while designing in systems to help mitigate negative impacts on the environment, and also decrease contaminated storm water runoff - among others.
Storm Water Runoff - SWR: is rain water that falls and flows over surfaces such as parking lots, streets, roofs, sidewalks, etc... and then "runs off" the surfaces. Snow melt can also be considered runoff. Storm Water from intense rain events is natural. Whereas, Storm Water Runoff over man-made impervious surfaces is not natural. In nature, SWR occurs over granite faced mountain sides, icebergs, rock outcroppings dominated by flat stone surfaces and ice, etc... These natural areas are intended for nature to originate the water-borne sources for brooks, streams, creeks and rivers, etc... and eventually , ponds, wetlands, lakes and oceans. SWR is an environmental problem where the runoff transports pollutants along with it. And in heavy rain events this storm water runoff can cause a combined sewer overflow (CSO) into local waterways.