Flood protection

The Chulalongkorn University (CU) Centenary Park was created to provide a green space for the city and celebrate Chulalongkorn University’s 100th anniversary. Located in the centre of shopping and commerce, the park is designed as a multi-functional “urban forest”, which serves as an oasis for the residents and visitors of Bangkok, who can spend quality leisure time in a lush and pleasant environment. The park includes constructed wetlands with rain gardens, retention ponds, an underground water drainage system and green roof areas. Opened in 2017, Chulalongkorn Centenary Park is the first critical piece of green infrastructure in Bangkok to mitigate detrimental ecological issues and disaster risk reduction. Unlike other public parks around the city, this one is the first in Thailand to demonstrate how a park can help reduce urban flood risks and help the city confront climate change, all while offering city dwellers a place to reconnect with nature. Designed with various ecological design components, the park reminds the city of ways to live with water rather than fear it. [1, 2, 4]

The Rioni River basin is the second largest in Georgia, originating in the Greater Caucasus range and flowing into the Black Sea, traversing the town of Samtredia. Samtredia has been affected directly on many occasions by floods that have become a current occurrence in the Rioni River basin as of late. The underlying causes of vulnerability to climate change in the Rioni basin can be categorised into 1) physical factors –direct manifestations of climate change, 2) factors caused by anthropogenic intervention – those related to the harmful ways in which humans have and continue to interact with the environment which has exacerbated vulnerability and 3) Institutional factors – related to the legislative/regulatory barriers placed by government and other institutions, as well as limited capacity (human and resources) to manage climate change vulnerability. Flooding has been harmful not only to the local population but also to the biodiversity of the area, which suffered losses and an ecological imbalance and a disruption in the habitat patterns of local fauna. Many of these issues became the focal point of an activity developed by the Adaptation Fund alongside the Georgian government as early as 2012. The intervention stretched for 4 years and involved several localities in the Rioni River Basin, including Samtredia municipality, consisting of creating bank terracing, vegetative buffers, and tree revetments in order to address floods related to the Rioni River basin and the localities it traverses. (1,2)

The Beddagana Wetland Park is located in Sri Jayawardenapura Kotte, Sri Lanka's administrative capital. The wetland park plays an important role in flood regulation and keeping the city cool during periods of extreme heat. The city is located in the Colombo district and the project contributes to the flood management goals of the Metro Colombo Urban Development Project (MCUDP). It demonstrates how a wetland can be preserved while promoting eco-tourism and improved livability in the city. The target area is located within the Sri Jayewardenapura-Kotte municipality and is a part of Parliament Lake. While focusing on the protection of the wetland habitat as a flood-retention area, the project also supports selecting investments aimed at the protection and landscaping of key areas within the target area to improve livability for local people living in and around the area, while providing access to much-needed recreational space. [2, 7]

The main rivers that cross Lilongwe are the Lilongwe, Lingadzi, Nankhaka and Chankhandwe Rivers, of which the Lilongwe River is the biggest and longest river and the primary source of water for Lilongwe city's residents. At 200 km long, besides its primary function, the river also supports several informal settlements and provides ecological, recreational, cultural and economic benefits. Despite these important functions that the river offers, it is still facing threats such as pollution, urban agriculture, sand mining, climate change effects, and a loss in the biodiversity of fauna and flora that this watercourse hosts. As it sustains a population of approx. 1 mil. inhabitants, the local authorities were interested in finding solutions to address the above threats. As early as 2016, ICLEI ( Local Governments for Sustainability), an international NGO that promotes sustainable development, worked alongside Lilongwe City Council and other stakeholders to protect the river as well as the people depending on it and implemented several actions, with the help of the local community. Eventually, this collaboration led to the issuing of a strategic plan for a sustainable and functional ecological corridor system in the heart of Lilongwe City. The Ecological Corridor aims to transform Lilongwe into a green, clean, prosperous, and resilient city, by ensuring the protection of its urban natural assets, and advancing complementary nature-based solutions. 1,2,3)

The Bluebelt programme in Staten Island was implemented as it "preserves natural drainage corridors including streams, ponds, and wetlands, and enhances them to perform their functions of conveying, storing, and filtering runoff precipitation or stormwater". (Ref. 2). By delivering "stormwater to engineered systems that are designed to mimic natural streams and ponds which...meander or wind back and forth, the water slows down naturally" (Ref. 1). These actions are intended to "help control flooding, pollution and erosion" (Ref. 2), whilst also providing open green areas for both local communities and a "diverse habitat for wildlife" (Ref. 2). Beginning in 1990, the Bluebelt programme has undergone continual expansion, recognising that "as New York City prepares for rising sea levels and heavier rains due to climate change, Bluebelts offer a natural and effective solution for stable and sound stormwater management" (Refs. 2 & 4). The Bluebelt now includes approximately 400 acres of freshwater wetland and riparian stream habitat and 11 miles of stream corridor (Ref. 4).

The project has seen the "installation of rock structures to reduce the energy of the water that is drained by conventional rainwater galleries and the strategic planting of certain plant species that, through phytoremediation, can mitigate the diffuse pollution that affects the body of the river" (Ref. 1). In combination, "these solutions aim to prevent erosion and landslides on the banks, stop the siltation of the river, improve water quality and strengthen the linear park as a leisure space increasingly demanded by the population in its surroundings" (Ref. 1). A demonstration project which occurred under ICLEI's INTERACT-Bio project, the implementation of NBS has also been accompanied by other measures which saw Lake Cabrinha be de-silted, a walking path, benches, and playground be built and LED lighting be installed" (Ref. 1).

Located in the Eastern part of Tanzania's mainland, the city of Dar es Salaam has been a fast urbanising centre in Sub Saharan Africa. A steady population increase represents implications related to increased human activities, such as encroachment of hazardous land, poor urban planning, as well as lack of infrastructure, placing considerable pressure on the good functioning of the city and causing a rapid loss of green areas and of trees. In counterbalancing these aspects, peri-urban agriculture, artisanal fishing, and nature-based tourism contribute substantially to the well being and livelihoods of the inhabitants of Dar es Salaam. Understanding that nature plays a significant role in the sustainable development of the city and to address the issues above, the municipality of Dar es Salaam, alongside several stakeholders, elaborated a so-called "Thematic Atlas of Nature’s Benefits to Dar es Salaam", tailored specifically for the city. One of the aims of the atlas is to tackle climate change effects that are threatening Dar es Salaam by keeping urban and peri-urban ecosystems intact while implementing nature-based solutions. It is a balancing act coupled with the fact that Dar es Salaam is located in a globally important biodiversity hotspot, the ‘East African Coastal Forest’. (1,2,3)

A rain garden has been implemented at the Fazenda Lagoa do Nado Municipal Park in Belo Horizonte. The rain garden has been created as "a solution that contributes to the runoff of rainwater, allowing the water to be filtered through vegetation and infiltrate into the soil", with this type of solution being recognised as a method which "recharge[s] the water table, increases biodiversity, improves the local microclimate and air quality" (Ref. 1). The rain garden has been created as a demonstration project within the wider INTERACT-Bio project which is led by the global Local Governments for Sustainability network, ICLEI (International Council for Local Environmental Initiatives) (Ref. 1). As summarised by President of the Municipal Parks and Zoobotany Foundation of Belo Horizonte, Sérgio Augusto Domingues, “This is an important experiment that enables solutions based on nature. The idea is that it, like other mechanisms, complements macro-drainage interventions, helping the city to be more resilient to extreme events related to climate change" (Ref. 3).
According to the Municipality of Belo Horizonte, the Multiannual Government Action Plan (PPAG) aims to implement 30 rain gardens in the municipality by 2025, each garden having an area of ​​150 square meters (Ref. 7).

Mauritania is one of the Sahelian countries most severely affected by the periods of drought occurring since 1968. The resulting desertification is exacerbated by human activities, which have compounded climatic factors, with direct consequences for an already precarious situation. Environmental degradation, responsible for the dangerous displacement of sand dunes in Mauritania, has wiped out homes, livestock and livelihoods throughout the desert country. In Nouakchott, Mauritania’s capital and biggest city, the coast are protected by a fragile wall of dunes at risk from natural erosion, sand mining, grazing of livestock on dune vegetation, and careless abuse of the landscape for leisure like dune racing. In this scenario, protecting the dunes is a priority, and the government is using World Bank financing to overcome the challenge. From a climate change perspective, the intervention addresses accelerating erosion that allows seawater to wash into the city, assaulting buildings, roads, fresh water supply and public space. From a biodiversity perspective, the intervention aims at sustaining the balance between the food for the livelihoods of the local population and the preservation of the rich coastal biodiversity. (1,2)

Monavale Vlei is an important wetland area within the city of Harare, characterised by miombo woodlands that play an important role in the fragile ecosystem of the Manyame catchment basin, the main supplier of water for the city of Harare and its suburbs. Throughout the years, Monavale has been subjected to a number of threats such as construction developments, dumping of waste, fires, illegal farming, invasive plants, informal agricultural practices and loss of biodiversity. To address some of these challenges the local community organized itself into a group - Conservation Society of Monavale (Cosmo) Trust, to protect the area and, with the help of the municipality of Harare and some international bodies, implemented a series of actions designed to protect the wetland and reduce the loss of biodiversity, among many others. In 2009 the NGO was awarded a United Nations Development Programme Global Environment Facility Small Grant. The intervention had 3 objectives: to restore parts of the wetlands, to advocate with the local and international authorities for the legislative protection of the wetlands, and to engage the scientific community in research regarding the wetlands. This enabled Cosmo to restore Monavale vlei to an almost pristine wetland state, and other UN funding has made possible several training and awareness projects for a wide range of audiences. (1,2,3)