Flood protection

The Kok River which runs through Chiang Rai City is in the process of being ecologically restored (Ref. 1). Having previously been a "lifeline for the city and various communities along its banks", sections of the river ran dry 20 years ago due to the construction of a large scale diversion channel and dredging by a major hotel (Ref. 2). In addition to reestablishing the river flow, restoration efforts are focusing on the opportunity to provide additional water storage, flood reduction and urban greening (Refs. 1 & 4). These improvements are considered particularly important given that the city of Chiang Rai is "expected to be affected by climate-induced drought as a result of changing rainfall patterns; rain which may also be heavy at times leading to excessive runoff into such channels; and flooding" (Ref. 4). To date, wetlands have been restored, and community benefits, such as a walking path, created (Ref. 3).

Improved water circulation and quality are further going to minimise the occurrence of breeding grounds for disease vectors (Ref. 4). Whilst already recognised as a problem, vector-borne and waterborne diseases are anticipated to become more prevalent due to increased temperatures associated with climate change (Ref. 4).

The redevelopment of the Bishan-Ang Mo Kio Park (Singapore) saw the naturalisation of the previously channelised Kallang River, as well as the installation of wetland cells as water cleansing biotopes and creation of butterfly habitats (Ref. 1).

The Kallang River was previously confined to a concrete canal that ran to the southern edges of Bishan-Ang Mo Kio Park (Ref. 1). The channel segregated the two residential areas situated on either side of the park, with the river's 2.7km continuous concrete channel being crossable at only certain defined points (Ref. 3). Following its naturalisation, culminating in 2012, the now 3.2km meandering river is considered the park's highlight, "merg[ing] seamlessly with the park's greenery" (Refs. 1 & 6), and creating a "blue-green recreational network which is well-integrated with nearby residential areas" (Ref. 2).

The Krubong landfill site has been proposed to undergo a "thorough and safe environmental rehabilitation program[me]" so that the site can be developed as a public park (Ref. 1). Following completion of a feasibility study, it is envisaged that significant rehabilitation work to address environmental degradation and restoration of natural habitats will be required, after which the site will be developed into a public park (Ref. 1). The programme remains in its planning stage, but seeks to address Sustainable Development Goals (SGDs) 11.6 and 15.1 through protecting, restoring and promoting sustainable use of ecosystems and reversing land degradation and/or biodiversity loss; and reducing the environmental impact of cities by paying special attention to waste management and providing access to safe, open public spaces (Ref. 1). At a more local level, the programme intends to complement additional programmes laid out in Melaka's Resilience strategy document, including promoting both cycling and pedestrian networks and reshaping public spaces in the city (Ref. 1).

In 2019, the public initiative "Let's return the rivers to the city" campaign united public forces around the Podborenka river, which flows through the territory of Izhevsk along its entire length [1, 4, 5]. In an urbanised environment, the river was abandoned due to water pollution, poor treatment of stormwater, road and industrial runoff, soil erosion, and due to presence of landfills in the valleys [1, 4, 7]. Therefore, the project's primary goal is to increase the efficiency of urban resources and the creation of new scenarios for resource use on the example of the space of the riverbed of a small river [3]. The project implementation contributes to improving the ecological situation of the Podborenka River, its embankment zone and biodiversity [1, 9]. Also, the project implementers paid particular attention to the education of young people, the development of volunteer movements, and raising the level of the ecological culture of the population [1, 2, 6, 7].

The project is part of a bigger initiative aimed at restoring the coastal forest near the city of Mahajanga in western Madagascar. Alongside 2 international NGOs, the community located in the bay next to the city of Mahajanga implemented the intervention with the ultimate goal being to transition the land into a protected area as part of the greater "Mahajanga Green Belt Project". The regrowing forest will form the northwestern end of the greater Mahajanga Green Belt, with the southeast meets the Ankarafantsika National Park. The project also has a gendered aspect as it aimed to employ mostly the women in the suburbs of the city. (1,3)

Quelimane is a port city in Mozambique. It lies below sea level right alongside the Good Signs river (Rio Bons Sinais), and just a few kilometres from the coast. The frequent extreme weather phenomena such as rain and marine flooding render the city extremely vulnerable to climate risks. In 2013, the municipality concluded that one solution involves restoring large areas of mangroves, which act as a nature-based solution against flooding, helping to stem the tide by preventing soil erosion. In the past mangroves were cut down by the locals for building and cooking but now with the help of the municipality and local communities, the trees are restored and used as the first line of defence against climate change (1).

Xalapa is located beneath towering volcanic peaks in the Sierra Madre Oriental, and the city is crossed by at least five minor streams, seven rivers, and it has four man-made lakes and one lagoon in its territory. Its natural ecosystem represents “1% of the national forest area and hosts more than 12% of forest biodiversity” [1]. However, unplanned expansion has resulted in deforestation and the inadequate management of its waterways. In addition, forests, riparian corridors and wetlands have been cleared for agriculture and urban infrastructure. These disruptions to the environment have increased the frequency and intensity of flooding in the city [2]. To meet the environmental challenges, the United Nations Environment Programme (UNEP) and Mexico's Secretariat of Environment and Natural Resources-SEMARNAT launched an initiative as part of UNEP's multi-city CityAdapt Project, backed by the Global Environment Facility (GEF) [3]. The project focuses on four interventions to improve resilience to climate change through NbS: 1) riparian restoration along the Papas urban river; 2) ecological restoration of the Estropajo Hill; 3) installation of rainwater systems within the most vulnerable areas in Xalapa; and 4) implementation of an artificial wetland at schools [2,4].

Since 2008, the City of Portland, Oregon has used various policies and programming to encourage the use of eco-roofs (vegetated roofs) throughout the city to address stormwater management (Ref. 2,3,4). In addition to stormwater management, eco-roofs have the benefits of: saving energy, reducing pollution and erosion in waterways, preserving fish habitats, creating new habitats for birds and insects, absorbing carbon dioxide, cooling urban heat islands, filtering air pollutants, and providing urban green space (Ref. 1,5). From 2008 to 2012, the City of Portland used the Ecoroof Incentive program to encourage property owners and developers to construct ecoroofs (Ref. 4,5,12). In 2018, the City of Portland adopted a mandate for ecoroofs in new buildings (Ref. 2,3,12). These policies and programs led to a growing interest in the use of ecoroofs, and resulted in the construction of over 130 ecoroofs (Ref. 3,4,11).

The Tagabe Riparian Corridor Regeneration Project is an integrated catchment project ‘designed to build resilience into the riparian system to safeguard human wellbeing in the face of current and future climate change challenges and key population/ resources demands’ (Ref. 4). The project is focused on the ‘riparian margins of mid to lower catchment streams in the Tagabe catchment’ (Ref. 4,5). Activities consist of ‘riparian revegetation and stream bank protection; sustainable land management of adjacent farmlands; and point source pollution prevention and remediation’ through a series of 5-year management periods (Ref. 4,5). The project was part of the larger PEBACC (Pacific Ecosystem-based Adaptation to Climate Change) project and is now supported by the Vanuatu Government and various other initiatives like the Pacific R2R – Ridge to Reef programme (Ref. 8,9).

Thammasat Urban Rooftop Farm (TURF) is Asia's largest organic rooftop farm, which unites principles of modern landscape design with traditional agriculture of rice terraces, to transform wasted space into productive land. By mimicking traditional rice terraces, Thammasat University Urban Farming Green Roof has become an all-in-one solution–as a public green space, urban organic food source, water management system, energy house, and outdoor classroom–which serves as an adaptation model for anticipated climate impacts that can be implemented and developed across Thailand and Southeast Asia. Additionally, the mountain-shaped Thammasat University Green Roof utilizes its vast space as an infinite source of clean energy, not only in terms of organic food but also solar power for the community. [1, 2, 3]