Renaturalization of rivers and other water bodies

The ‘City of 1,000 Tanks’ project offers a holistic solution to the problems of floods, water scarcity and pollution in Chennai (Ref. 1). The project's primary objective is to develop a "Water Balance Model" for the city, which involves collecting rainwater, treating wastewater and runoff pollution with decentralized nature-based solutions, as well as prevent climate-change-induced droughts and saline intrusion due to sea-level rise (Ref. 1, 2). This is achieved through developing various nature-based water management solutions and improving the recharge capacity of traditional temple tanks (Ref 1).
The project began in 2018, following the call for action event of the "Water as Leverage for Resilient Cities Asia" (a bilateral program spanning several Asian countries). The Water Balance Model is developed as a strategy with an incremental implementation process (Ref 1, 2). The project started with pilot projects and then progressed to flagship projects before full city-wide implementation (Ref. 3).

A 7-hectare pilot public project, the Tebet Eco park is located in South Jakarta in a neighbourhood that is densely populated. Previous to the intervention the park was in an acute state of deterioration and prone to floods as well as ecological degradation, as the park is streamed by a river which made it only more susceptible to heavy rains. As such, the municipal authorities of Jakarta planned to revitalize the area by " increasing the hydraulic capacity of existing canal, improving site-wide pedestrian connectivity, and adding new recreation program". This meant that the park was transformed by planting and conserving new and older trees, as well as using vegetation and natural embankments. Furthermore, the implementer planted riparian vegetation to improve water quality by filtering and cleansing surrounding runoff, which also enhanced the site's biodiversity. Besides these elements, a thematic garden, a forest buffer, and a community garden were implemented complementing the entire eco-design that the park aimed for. The park's rehabilitation focused greatly on the human element as it was paramount to provide maximum benefits for park users, the surrounding natural habitats and species, as well as increasing the land value of the area. (2,3,7)

Vinh is the biggest city in north-central Vietnam and is the hub for economic and cultural development in the region. As of 2018, the city has a population of approx. 500,000 inhabitants and is located on the Ca River delta, 160 miles (260 km) south of Hanoi. Flooding and poor environmental sanitation are major impediments to the development of Vinh City. The drainage system of the city is comprised of four catchment basins connected to Rao Dung, Ke Gai, Vinh and Lam Rivers. Among the four, the Vinh River is flowing through the central wards and communes of Vinh City and is one that becomes sensitive to severe flooding events frequently (2,3).
Recently (in 2021), with support from the World Bank, the government initiated a program, the Vinh City Priority Infrastructure and Urban Resilience Development Project (VPIUR), which is expected to bring a new look to the river, reduce the risk of flooding in urban areas and strengthen urban management capacity to adapt to climate change. This project has several sub components and one of them is a river rehabilitation and upgrade under the form of riverbank green, sanitation, and flood risk management (1, 3).
The implementation includes a comprehensive set of structural and non-structural interventions, including flood control systems and nature-based solutions, wastewater collection and treatment infrastructure, and key transport links. The project aims to transform it into green public spaces which are to be constructed under the project. The project also aims to invest in developing green public spaces along the Vinh riverbank and a new regulation lake. (3)

The green infrastructure master plan of Udon Thani aims to prepare the city for the future development challenges by offering a new infrastructure network that can mitigate flood and drought while enhancing community and public space within the municipality. Udon Thani is an important economic city in the northeastern part of Thailand and is growing rapidly. With urbanization and climate change trends, the city is experiencing water supply and flood challenges. The masterplan consists of four main design strategies including canal restoration, green streets, retention parks and wetland areas. All four mains strategies create multi-functional spaces that promote environmental and social benefits together. Aside from slowing water flow which allow infiltration and retaining water, these spaces act as park and community garden which offer passive and active recreational activities. In total, 14 sub-projects were proposed together with cost-benefit analysis. (Ref. 1,2,3,4) Currently, the first project is under construction, which is a canal restoration (Huay Mak Khaeng). The construction is expected to finish in 2024. (Ref. 6,7,8)

Iloilo River Esplanade is a promenade and linear park along the Iloilo River, created as part of the Iloilo River Rehabilitation Project. It is the largest linear park in the Philippines and was designed by the landscape architect Paulo Alcazaren. The esplanade is one of a kind in the country that aims to foster biodiversity, store carbon by mangroves and provide protection from possible flood damages. Furthermore, the project aspires to build a lifestyle hub for the locals and promotes educational eco-tourism. The site was an existing dike road devoid of shade and originally built just as a flood control measure. The redesign has showcased its effect on public amenities, received several recognitions and has become a magnet for tourists in this city. [1, 3, 6, 7]

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 Ras Mekonnen Urban Park is part of a larger intervention developed by ICLEI (an international NGO focused on the promotion of sustainable development) with the Addis Ababa municipality alongside the Shega river that crosses a nearby neighbourhood. The location of the park was initially used by locals as a dumping site affecting not only the quality of life of the inhabitants but also contributing to the environmental degradation of the area. As more and more people discarded their waste here, the small river running through the site, a tributary of the Shega River, became increasingly overgrown and inaccessible, resulting in a derelict, run-down space in an otherwise vibrant urban area. As such, action was needed, which eventually resulted in the rehabilitation of the river and the creation of the park, which now can be enjoyed by all the inhabitants of the Ras Makonnen neighbourhood. (1,2)

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).