Green Infrastructure is a strategically planned network of natural and semi-natural spaces with environmental features that recreate the natural water cycle. Green Infrastructure often uses landscaping technologies to direct localized flooding, and store water in the ground. Green Infrastructure helps manage the impacts of urbanization by increasing the amount of open soil in the urban environment.
Gray infrastructure is traditional stormwater infrastructure in the built environment such as gutters, drains, pipes, retention basins, dams, seawalls, roads, pipes or water treatment plants. Using grey infrastructure, water runs off into the street and storm sewer systems, which then leads to more street flooding and sewer backups, increased pressure on infrastructure, more runoff pollutants entering waterways, and increased subsidence.
Although popular during the urbanization of the United States, the country is now seeing unintended consequences from paving and reshaping the environment including heat island effect, flooding, noise pollution, and mental health issues. Challenges surrounding grey infrastructure include funding and public investment, maintenance, and increased urbanization.