Editing IPCC:AR6/WGII/Chapter-12 (section)

===== 12.5.5.3.2 Green and Grey Infrastructure =====

<div id="h4-6-siblings" class="h4-siblings"></div>

Hybrid solutions, combining green and grey infrastructure (GGI), have been adopted for better efficiency in flood control ( [[#Ahmed--2019|Ahmed et al., 2019]] ; [[#Drosou--2019|Drosou et al., 2019]] ; [[#Romero-Duque--2020|Romero-Duque et al., 2020]] ), sanitation, water scarcity, landslide prevention and coastal protection ( ''high confidence'' ) ( [[#12.5.6.4|Section 12.5.6.4]] ; [[#Mangone--2016|Mangone, 2016]] ; [[#Depietri--2017|Depietri and McPhearson, 2017]] ; [[#Leal%20Filho--2018|Leal Filho et al., 2018]] ; [[#McPhearson--2018|McPhearson et al., 2018]] ). The adoption of NbS, which embraces well-known approaches such as GI and EbA ( [[#Pauleit--2017|Pauleit et al., 2017]] ; [[#Le--2020|Le, 2020]] ), has increased (Box 1.3). The Fund for the Protection of Water (FONAG) and the Participative Urban Agriculture (AGRUPAR) are initiatives using NbS in Quito ( [[#12.6.1|Section 12.6.1]] ). An example of GGI is a stormwater detention pond as a water storage solution to flood prevention, allowing multiple uses of an urban space, and adapting and revitalising a degraded area in Mesquita, Rio’s metropolitan region ( [[#Jacob--2019|Jacob et al., 2019]] ). These systemic and holistic solutions still need to overcome governance and sectorial barriers to be more widely adopted ( [[#Herzog--2019|Herzog and Rozado, 2019]] ; [[#Wamsler--2020|Wamsler et al., 2020]] ; [[#Valente%20de%20Macedo--2021|Valente de Macedo et al., 2021]] ).

Managing water in cities in an adaptive way has been central to reducing impacts such as floods and contributes to water security ( ''high confidence'' ) ( [[#Van%20Leeuwen--2016|Van Leeuwen et al., 2016]] ; [[#Okumura--2021|Okumura et al., 2021]] ). Many cities facing frequent heavy storms that impact mostly underprivileged communities, slums and vulnerable areas could benefit from integrated NbS for disaster risk reduction and adaptation ( ''high confidence'' ) ( [[#Sandholz--2018|Sandholz et al., 2018]] ; [[#Ronchi--2019|Ronchi and Arcidiacono, 2019]] ). A study covering 70 Latin American cities estimated that 96 million people would benefit from improving main watersheds with GI ( [[#Tellman--2018|Tellman et al., 2018]] ). In several municipal climate plans, NbSs were introduced mainly to enhance rainwater management, reduce energy consumption and urban heat areas, improve water quality, prevent landslides and set aside green areas ( ''high confidence'' ) ( [[#Gobierno%20de%20la%20Ciudad%20de%20Buenos%20Aires--2015|Gobierno de la Ciudad de Buenos Aires, 2015]] ; [[#Municipio%20del%20Distrito%20Metropolitano%20de%20Quito--2020|Municipio del Distrito Metropolitano de Quito, 2020]] ; [[#Prefeitura%20Municipal%20de%20Curitiba--2020|Prefeitura Municipal de Curitiba, 2020]] ; [[#Alcaldía%20de%20Medellín--2021|Alcaldía de Medellín, 2021]] ; [[#Municipalidad%20de%20Lima--2021|Municipalidad de Lima, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ; [[#Prefeitura%20do%20Município%20de%20São%20Paulo--2021|Prefeitura do Município de São Paulo, 2021]] ). São Paulo’s project for Jaguaré River proposes a large-scale landscape transformation applying innovative multi-functional NbSs instead of exclusively large, expensive and monofunctional hard-engineered solutions to manage stormwater ( [[#Marques--2018|Marques et al., 2018]] ; [[#Herzog--2019|Herzog and Rozado, 2019]] ). In Bogota, the Humedales Foundation has restored wetlands to enhance areas near the Van Der Hammen reserve to improve water quality and quantity, restore habitat for biodiversity and provide flood protection ( [[#Portugal%20Del%20Pino--2020|Portugal Del Pino et al., 2020]] ). In Petrópolis, a medium-sized city in the hills of Rio de Janeiro state, the water service company has implemented 10 NbS multi-functional micro wastewater treatment plants in low-income areas, helping to reduce cascading impacts of storms, floods and epidemics ( [[#Herzog--2019|Herzog and Rozado, 2019]] ). In Costanera Sur, Buenos Aires, a public initiative to protect an auto-regenerated River Plate bank, which had received demolition material to create land, currently offers numerous ecosystem services for residents and attract visitors, activating the tourist industry and helping reducing riverine floods ( [[#Bertonatti--2021|Bertonatti, 2021]] ; [[#OICS--2021|OICS, 2021]] ).

A hybrid solution to water management that merges traditional interventions in urban areas with sustainable urban drainage systems (SUDSs) ( [[#Davis--2017|Davis and Naumann, 2017]] ), considering small-scale low-impact development (LID) measures scattered over the watershed instead of concentrate huge hydraulic grey structures, can help reduce the risk and damage of flooding ( ''high confidence'' ) ( [[#Miguez--2014|Miguez et al., 2014]] , 2015a; [[#Depietri--2017|Depietri and McPhearson, 2017]] ; [[#Da%20Silva--2018a|Da Silva et al., 2018a]] ; [[#de%20Macedo--2018|de Macedo et al., 2018]] ). Quito’s climate plan explicitly cites the strategy for implementing blue and grey infrastructure to reduce risk due to extreme precipitation and its associated impacts such as flooding and landslides and the possible impact of water scarcity ( [[#Municipio%20del%20Distrito%20Metropolitano%20de%20Quito--2020|Municipio del Distrito Metropolitano de Quito, 2020]] ). The Integrated Iguaçu-Sarapuí River Basin Flood Control Master Plan, in Rio’s metropolitan area, combines different solutions to flood protection, focusing on river restoration by retrofitting levee systems combined with adapting land use to provide a multi-functional landscape as an alternative to bring together green and grey solutions, creating urban parks to prevent further paving and avoid irregular occupation of riverbanks and provide storage capacity for damping flood peaks ( [[#Miguez--2015b|Miguez et al., 2015b]] ).

Many cities are implementing adaptation measures on integrated water and flood management systems ( [[#Sarkodie--2019|Sarkodie and Strezov, 2019]] ), improving basic sanitation services ( ''medium confidence: medium evidence, high agreement'' ). The main strategies are established by NAPs periodically focusing on improving water distribution network and reservoir systems, as in Honduras ( [[#Government%20of%20Honduras--2018|Government of Honduras, 2018]] ) and Ecuador ( [[#Mills-Novoa--2020|Mills-Novoa et al., 2020]] ), sewage and effluent treatment, as in Guatemala, Brazil and Paraguay ( [[#Government%20of%20Brazil--2007|Government of Brazil, 2007]] ; [[#Government%20of%20Guatemala--2016|Government of Guatemala, 2016]] ; [[#Government%20of%20Paraguay--2017|Government of Paraguay, 2017]] ), facing water scarcity and environmental degradation. Local authorities follow this guideline in an effort to maintain and upgrade existing drainage systems in Georgetown ( [[#Mycoo--2014|Mycoo, 2014]] ) or in Medellin, focusing on improving drainage systems to prevent landslides or flooding ( [[#Núñez%20Collado--2020|Núñez Collado and Wang, 2020]] ; [[#Alcaldía%20de%20Medellín--2021|Alcaldía de Medellín, 2021]] ). Rio de Janeiro has constructed three large stormwater detention reservoirs to deal with frequent flood, ( [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2015|Prefeitura da Cidade do Rio de Janeiro, 2015]] ), adopting a set of exclusively grey solutions, not combined into a NbS that could improve urban flood resilience ( [[#Rezende--2019|Rezende et al., 2019]] ). The main proposed actions still consider the traditional approach in improving the hydraulic capacity of urban drainage systems as an adaptive measure ( ''high confidence'' ) (Gobierno de la Ciudad de Buenos Aires, 2020; [[#Prefeitura%20Municipal%20do%20Salvador--2020|Prefeitura Municipal do Salvador, 2020]] ; [[#Municipalidad%20de%20Lima--2021|Municipalidad de Lima, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ). In addition to this strategy, several local plans propose actions for the retention and storage of rainwater, both in urban drainage networks on a smaller intervention scale ( [[#Prefeitura%20Municipal%20de%20Curitiba--2020|Prefeitura Municipal de Curitiba, 2020]] ) and along rivers and canals with large-scale works ( ''medium confidence: medium evidence, high agreement'' ) (Gobierno de la Ciudad de Buenos Aires, 2020; [[#Prefeitura%20Municipal%20de%20Curitiba--2020|Prefeitura Municipal de Curitiba, 2020]] ; [[#Alcaldía%20de%20Medellín--2021|Alcaldía de Medellín, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ).

<div id="12.5.5.3.3" class="h4-container"></div>

<span id="mobility-and-transport-system"></span>