Green infrastructure
Green infrastructure or blue-green infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by building with nature.[1] The main components of this approach include stormwater management, climate adaptation, the reduction of heat stress, increasing biodiversity, food production, better air quality, sustainable energy production, clean water, and healthy soils, as well as more anthropocentric functions, such as increased quality of life through recreation and the provision of shade and shelter in and around towns and cities.[2][3] Green infrastructure also serves to provide an ecological framework for social, economic, and environmental health of the surroundings.[4] More recently scholars and activists have also called for green infrastructure that promotes social inclusion and equity rather than reinforcing pre-existing structures of unequal access to nature-based services.[5]
Green infrastructure is considered a subset of "Sustainable and Resilient Infrastructure", which is defined in standards such as SuRe, the Standard for Sustainable and Resilient Infrastructure. However, green infrastructure can also mean "low-carbon infrastructure" such as renewable energy infrastructure and public transportation systems (See "low-carbon infrastructure").[6] Blue-green infrastructure can also be a component of "sustainable drainage systems" or "sustainable urban drainage systems" (SuDS or SUDS) designed to manage water quantity and quality, while providing improvements to biodiversity and amenity.[7]
Terminology[edit]
Ideas for green urban structures began in the 1870s with concepts of urban farming and garden allotments.[1] Alternative terminology includes stormwater best management practices, source controls, and low impact development (LID) practices.[18]
Green infrastructure concepts originated in mid-1980s proposals for best management practices that would achieve more holistic stormwater quantity management goals for runoff volume reduction, erosion prevention, and aquifer recharge.[19] In 1987, amendments to the U.S. Clean Water Act introduced new provisions for management of diffuse pollutant sources from urban land uses, establishing the regulatory need for practices that unlike conventional drainage infrastructure managed runoff "at source." The U.S. Environmental Protection Agency (EPA) published its initial regulations for municipal separate storm sewer systems ("MS4") in 1990, requiring large MS4s to develop stormwater pollution prevention plans and implement "source control practices".[20] EPA's 1993 handbook, Urban Runoff Pollution Prevention and Control Planning, identified best management practices to consider in such plans, including vegetative controls, filtration practices and infiltration practices (trenches, porous pavement).[21] Regulations covering smaller municipalities were published in 1999.[22] MS4s serve over 80% of the US population and provide drainage for 4% of the land area.[23]
Green infrastructure is a concept that highlights the importance of the natural environment in decisions about land-use planning.[24][25] However, the term does not have a widely recognized definition.[26][27] Also known as “blue-green infrastructure”,[28] or “green-blue urban grids”[1] the terms are used by many design-, conservation- and planning-related disciplines and commonly feature stormwater management, climate adaptation and multifunctional green space.
The term "green infrastructure" is sometimes expanded to "multifunctional" green infrastructure. Multifunctionality in this context refers to the integration and interaction of different functions or activities on the same piece of land.
The EPA extended the concept of “green infrastructure” to apply to the management of stormwater runoff at the local level through the use of natural systems, or engineered systems that mimic natural systems, to treat polluted runoff.[29] This use of the term "green infrastructure" to refer to urban "green" best management practices contributes to the overall health of natural ecosystems, even though it is not central to the larger concept.
However, it is apparent that the term “blue-green infrastructure” is applied in an urban context and places a greater emphasis on the management of stormwater as an integral part of creating a sustainable, multifunctional urban environment.[28] At the building level, the term "blue-green architecture" is used, which implements the same principles on a smaller scale. The focus here is on building greening with water management from alternative water resources such as grey water and rainwater.[30]
Types of green infrastructure[edit]
Urban forests[edit]
Urban forests are forests located in cities. They are an important component of urban green infrastructure systems. Urban forests use appropriate tree and vegetation species, instead of noxious and invasive kinds, which reduce the need of maintenance and irrigation.[53] In addition, native species also provide aesthetic value while reducing cost. Diversity of plant species should also be considered in design of urban forests to avoid monocultures; this makes the urban forests more durable and resilient to pests and other harms.[53]
Examples[edit]
Beijing, China[edit]
A good example of green infrastructure principles being applied at landscape scale is the Beijing Olympic site. First developed for the 2008 Summer Olympics but used also for the 2022 Winter Olympics, the Beijing Olympic site covers a large area of brownfield redevelopment in the northern sector of the city between the 4th and 5th ring roads. The central green infrastructure feature of the Olympic site is the "Dragon-shaped river" – a complex of retention basins and wetlands covering more than a half million square metres configured to look from the air like a traditional Chinese dragon.
Implementation[edit]
Barriers[edit]
Lack of funding is consistently cited as a barrier to the implementation of green infrastructure. One advantage that green infrastructure projects offer, however, is that they generate so many benefits that they can compete for a variety of diverse funding sources. Some tax incentive programs administered by federal agencies can be used to attract financing to green infrastructure projects. Here are two examples of programs whose missions are broad enough to support green infrastructure projects: