Nairobi River Basin Programme (NRBP)
Rapid urbanization and a population density of 6,247 people per km² have placed significant stress on Nairobi's natural resources (Ref 1). The 40-km long Nairobi River Basin, originating from the Ondiri Swamp, serves as a vital water source for the city (Ref 1, 2). However, it has suffered severe pollution from untreated sewage, solid waste, industrial contaminants, plastics, and agricultural runoff (Ref 1, 3). This degradation has had a serious impact on the ecosystem, local residents, and biodiversity (Ref 3).
To address these issues, the Nairobi River Basin Programme (NRBP), sponsored by UNEP, was launched in 1999 (Ref 4). Since then, government and non-state actors have worked together on solid waste management, riparian restoration, and wastewater control (Ref 1). The program was implemented in two phases: Phase I (2003–2006) and Phase II (2006–2009), involving stakeholders from the government, private sector, and civil society (Ref 1, 4, 5). Despite these efforts, a study from 2017 found significant tree removal along the river, and between 1988 and 2014, encroachment into the 30-meter riparian buffer zone dramatically increased, particularly between 2010 and 2014, further degrading the river’s health (Ref 1).
To address these issues, the Nairobi River Basin Programme (NRBP), sponsored by UNEP, was launched in 1999 (Ref 4). Since then, government and non-state actors have worked together on solid waste management, riparian restoration, and wastewater control (Ref 1). The program was implemented in two phases: Phase I (2003–2006) and Phase II (2006–2009), involving stakeholders from the government, private sector, and civil society (Ref 1, 4, 5). Despite these efforts, a study from 2017 found significant tree removal along the river, and between 1988 and 2014, encroachment into the 30-meter riparian buffer zone dramatically increased, particularly between 2010 and 2014, further degrading the river’s health (Ref 1).
Requalification of Viale Trieste
In 2022, the municipality of Cagliari launched a project to revitalize Viale Trieste, one of its avenues, by redesigning its roads and pedestrian areas and adding new green spaces. The project covers approximately 1,300 meters and 36,500 square meters, and will be completed in two phases, each focusing on different sections of the avenue. With a budget of 12 million euros, funded by municipal, national, and EU resources, the aim is to transform Viale Trieste into a vibrant, accessible, and attractive space for everyone.
The renewal will introduce new green spaces and improved drainage systems to enhance soil permeability. As part of this, some trees will be relocated to other areas of the city to address root issues and improve survival rates. Dead or unstable ficus trees will be removed, while 79 new trees will be planted. Older ficus trees will be relocated to city parks, with younger ones planted along the avenue to prevent pavement damage and promote sustainability. The project also includes upgrading water supply and drainage systems to manage stormwater more effectively, reducing the risk of flooding and improving sustainability. Public lighting will be modernized, with new street lamps and dedicated lighting for pedestrian and bicycle paths to make the area safer and more welcoming after dark.
However, the community has expressed concerns about the project, citing safety issues, delays, disruptions, and poor communication from officials. There is also significant opposition to replacing the historic ficus trees, valued for their environmental and historical significance, with Chinese pear trees and younger ficus (Refs. 1, 2, 3, 4, 5, 6, 11, 16).
The renewal will introduce new green spaces and improved drainage systems to enhance soil permeability. As part of this, some trees will be relocated to other areas of the city to address root issues and improve survival rates. Dead or unstable ficus trees will be removed, while 79 new trees will be planted. Older ficus trees will be relocated to city parks, with younger ones planted along the avenue to prevent pavement damage and promote sustainability. The project also includes upgrading water supply and drainage systems to manage stormwater more effectively, reducing the risk of flooding and improving sustainability. Public lighting will be modernized, with new street lamps and dedicated lighting for pedestrian and bicycle paths to make the area safer and more welcoming after dark.
However, the community has expressed concerns about the project, citing safety issues, delays, disruptions, and poor communication from officials. There is also significant opposition to replacing the historic ficus trees, valued for their environmental and historical significance, with Chinese pear trees and younger ficus (Refs. 1, 2, 3, 4, 5, 6, 11, 16).
Green Corridor "Lazaro Cardenas" in New Belgrade
Named after the former Mexican president Lázaro Cárdenas, this green corridor project stretches over 4,5 km throughout one of the most densely populated areas in Belgrade. It was first built in the 1970s, connecting the building blocks 45, 44 and 70 of Novi Beograd, but has deteriorated since then (Ref. 4,9). Given the fact that close to 40.000 people live in the area which its highly vulnerable to climate change, action was taken to fully reconstruct the corridor for the benefit of local and surrounding residents (Ref. 3,4).
The project was implemented in three phases, according to the three blocks adjacent to the construction site starting in 2019. During the third implementation phase in 2022, however, major delays occurred due to disagreements with the local neighbourhood association "Common Action Block 70 and 70a", which demanded to be taken into consideration in the project's design (Ref. 2,5). Despite some cooperation between the responsible authority (Greenery Belgrade) and the association, demands could not be met (Ref. 5). In the end, the project was carried out as originally planned by the authorities, with a delay of approximately one year. Ultimately, the green corridor provides ample amenities for sports (bicycle lanes, basketball courts, playgrounds, etc.) and recreational activities (benches, chess area) as well as low-barrier infrastructure for all age groups (Ref. 9).
The project was initiated by President Aleksandar Vučić and supported by the current mayor of Belgrade, Šapić, who both have roots in the district (Ref. 4,6).
The project was implemented in three phases, according to the three blocks adjacent to the construction site starting in 2019. During the third implementation phase in 2022, however, major delays occurred due to disagreements with the local neighbourhood association "Common Action Block 70 and 70a", which demanded to be taken into consideration in the project's design (Ref. 2,5). Despite some cooperation between the responsible authority (Greenery Belgrade) and the association, demands could not be met (Ref. 5). In the end, the project was carried out as originally planned by the authorities, with a delay of approximately one year. Ultimately, the green corridor provides ample amenities for sports (bicycle lanes, basketball courts, playgrounds, etc.) and recreational activities (benches, chess area) as well as low-barrier infrastructure for all age groups (Ref. 9).
The project was initiated by President Aleksandar Vučić and supported by the current mayor of Belgrade, Šapić, who both have roots in the district (Ref. 4,6).

