Water management (SDG 6)

The Rajakori lake rejuvenation project aimed at reviving an existing lake using a natural and sustainable treatment system, the "Scientific Wetland with Active Biodigester (SWAB)". SWAB technology uses a two-step process involving (i) a sedimentation tank equipped with a biodigester and (ii) a constructed wetland system. The untreated sewage waste is passed through this two-step process that uses microbes and plants to reduce pollutant levels. The project also involved redeveloping the public space around the lake for community use (Ref 1,2). Before 2017, the lake was overfilled with sewage and waste from nearby neighbourhoods due to a lack of proper sewage management. Initiated by the Delhi Government, the project aimed at using low-cost natural methods rather than conventional techniques involving concretized bases and chemicals to treat water (Ref 1, 4). Due to its success and cost-effectiveness, this project now serves as an excellent example for other projects within Delhi (Ref 5).

Bangladesh is a country prone to floods and waterlogging, which results in two-thirds of this nation's land being transformed into wetlands each year. As such, much land becomes unavailable and the restricted access to it causes food insecurity as well as severe environmental pressure on the flora, fauna and ecosystems. The impact is even more serious as agriculture is one of the most important contributors to Bangladesh's GDP (1).
To respond to most of the climate challenges and food insecurities, in 2007 the International Union for Conservation of Nature (IUCN) and the humanitarian agency Care International, alongside other partners (including the Bangladeshi government), launched floating gardening (artificial islands, that simply rise and fall with the swelling waters) pilot project in the peri-urban area of the Gopalganj and other close by districts (1,2).
Floating gardens known locally as Baira are an old practice of crop cultivation in the wetlands of Bangladesh, the previous agricultural land, which got destroyed by the floods. The practice consists of piling together a number of dense layers of aquatic weeds like water hyacinth, duckweed, or paddy stubs and letting them decay. Afterwards, they're combined with silt and cow dung and inserted with plant/vegetable seeds left to flourish. On these beds, farmers cultivate fruits and vegetables like turmeric and ginger as well as okra, bitter gourd, snake gourd, spinach, and brinjal. In addition to veggies, rice seedlings can occasionally be raised. As a result, floating gardens are available to everyone, affordable, dependable, and completely in harmony with nature. (2,3) Furthermore, this aquatic farming practice has been shown to be highly effective in tackling the consequences of climatic variability and climate change like prolonged water-logging (3). The intervention has benefited approx. 2,000 families in the district of Gopalganj and it has opened the route for further projects that supported the practice of floating gardens (4).

In 2008, Mahidol University in Thailand announced its revised five-year Green Campus master plan titled 'A Promised Place to Live and Learn with Nature' for its main Salaya Campus. The scheme aimed to promote a green conscience and lifestyle for its students and faculty through sustainable campus developments that consider social and environmental aspects. The university's objectives were to achieve energy conservation, environmental sustainability, and social cohesion and well-being. The main features of the master plan included the creation and maintenance of green open spaces covering at least 70% of the campus premises, optimization of land use, transformation of infrastructure to encourage cycling, creation of outdoor learning, recreational and research areas, and enhancement of local biodiversity. The master plan also covered guidelines and targets for energy consumption, waste, and water management in the campus buildings. The Siri Ruckhachati Nature Park, the university's arboretum, was also redesigned with green and blue areas playing a role in flood management. Following the 'Green Campus' master plan, Mahidol University developed its existing mission further and became an 'Eco University' in 2012 and a 'Sustainable University' in 2021. These two missions focus primarily on reducing energy consumption and waste management.
(Ref.1,2,3,12)

The new office building of the Council of Engineers is located on one of the busiest streets of Bangkok, Thailand. The building aims to combine new engineering technology with aesthetic and function, while maximizing green area and promoting sustainability. The building's terraced green area lead the people up to the entrance on second floor and continue up to the sky garden on the forth floor. The main features of the garden are lush fauna with tree and shrub species, planters, multi-purpose open spaces and bio-filtration system that use plants to filter and divert rainwater. The project aims to acquire the platinum TREES building rating (a green building certificate in Thailand) and it is in the process of applying for the certificate. (Ref. 1,2,3,5)

Balili River, situated in the province of Benguet, is among the many urban rivers in the Philippines that suffer from severe pollution due to various human activities. Indiscriminate dumping of waste in almost all of its 23 tributaries is a significant contributor to the pollution. Despite this, the river remains a critical source of irrigation for farmers in La Trinidad who primarily grow strawberry and salad crops in the valley. However, the use of contaminated water from the river poses a direct threat to the food safety of consumers of these crops. Moreover, during the summer, the black water of the Balili River is a constant eyesore in the community. To address these environmental concerns, a pilot study was conducted aimed at exploring treatment options for the polluted water in Balili River. The study focused on assessing the use of local plants to restore biodiversity, conserve wildlife habitats, and test the phytoremediation potential of local macrophytes. The pilot area was established within the Organic Farm of Benguet State University near the main stream of the Balili river. The study set up two types of constructed wetlands (CW), a surface flow CW for floating plants and a horizontal subsurface flow CW for emergent plants. The results of the pilot study suggest that constructed wetlands could be an effective solution for cleaning up the Balili River. The implementation of constructed wetlands in Balili River can not only improve the water quality but also benefit the local community and ecosystem. [1,2]

The United Nations High Commissioner for Refugees (UNHCR) and its partners collaborated in 2018 to develop an ecosystem restoration project in the Rohingya Camps of Ukhiya, near Cox's Bazar. The main objective of this project was to mitigate the increased risk of landslides, slope instability, and flooding caused by flash floods and the vicinity of the Bakkhali River. The intervention included the planting of quickly growing native trees, shrubs, and grass species. Additionally, the project encompassed other measures such as vegetable cultivation on stream beds, biological soil stabilization methods, and plant-based wastewater treatments. To ensure the sustainability of the project, a network of future practitioners from the Bangladeshi and Rohingya communities was created. Moreover, environmental education and awareness activities were undertaken to complement the efforts of the project, with a particular focus on engaging young people from both the host and refugee communities to maximize its impact. The area where the project was implemented has been significantly affected by land and forest degradation over the last few decades, which has been exacerbated since the arrival of Rohingya refugees in 2017. Therefore, the project also involved other stakeholders such as the International Center for Conservation of Nature (IUCN), the Danish Refugee Council, the World Food Programme, the International Organization for Migration, and the Bangladesh government, each contributing in various capacities to achieve the project's objectives. (1,2,3,4)

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)

In 2005, a constructed wetland was established in Barangay Villareal, Bayawan City in order to improve a peri-urban settlement and promote domestic wastewater treatment with reed beds. The wetland covers an area of 2680 square metres and comprises two reed beds, with the first bed utilizing perforated pipes beneath a sand and gravel substrate for vertical flow filtering, and the second bed utilizing horizontal flow for biological filtering. The roots of the Phragmites karka reeds, which are used in the system, act as a natural filter, removing microorganisms and pollutants. The treated effluent is reused for various purposes, such as watering plants, firefighting, and irrigating ornamental plants and agricultural crops. The overarching objective of the initiative is to safeguard coastal waters from pollution caused by domestic wastewater and enhance residents' quality of life by providing safe sanitation and wastewater treatment facilities. Furthermore, the initiative seeks to showcase the effectiveness of constructed wetlands, encourage the use of locally available reeds for wastewater treatment, and conserve water and nutrients by reusing treated wastewater. [1,2].

The "Urban Forest" project focused on the establishment of the Mongolian-Korean Friendship Forest on a 40-hectare land in Dambadarjaa, Sukhbaatar district of the capital city, Ulaanbaatar. Previously known as the Forest Research and Development Center Arboretum Park, this area has a river running through it. The project, with a total cost of over 8 million EUR, was designed specifically to reduce air pollution in the capital, to create a healthy eco-environment for Ulaanbaatar residents to spend their leisure time and to raise awareness of the importance of forests and the benefits of trees in Mongolia. In total, 55,000 trees and shrubs of 36 different species were planted so far and the park boasts five different types of coniferous trees that thrive in Mongolia, including larch, pine, abies, cedar, and spruce, as well as deciduous trees such as birch, aspen, willow, lilac, and maple. The Urban Forest park also includes several facilities, such as a visitor information center, a playground, sport facilities, a natural arboretum and a ground fountain. The park will be operational and accessible to the public in 2023. The project was implemented between 2017 and 2022, as the second phase of the Korea-Mongolia Greenbelt Reforestation Initiative jointly developed by the Mongolian Ministry of Environment and Tourism (MET) and the Korea Forest Service (KFS). The Green Belt initiative was created with the overall aims to mitigate desertification, combat climate change, and reduce yellow dust and sandstorms in Mongolia.
(Ref. 1, 2, 3, 4, 5)

The Bakhawan Eco-Park is a 220-hectare mangrove forest located in Kalibo, Aklan province, Philippines, that started as a reforestation project in 1990. It was a joint project of the local government and a non-government organization, Kalibo Save the Mangroves Association (KASAMA), with the aim of reforesting the muddy shoreline of New Buswang district to protect the community from floods and storm surges [1,2]. Aside from preventing floods, the eco-park also provides locals with livelihood opportunities, mitigates the effects of climate change, and serves as a habitat for various mangrove tree species, birds, and marine life [1,2]. The project's success is largely attributed to the active involvement and support of the local community, with some families playing an integral role in the reforestation program. [2] Notably, the involvement of local women in the NBS initiative has contributed to the success of mangrove conservation. Some women have also taken on the task of policing the mangroves to prevent illegal tree-cutting by trespassers [4]. Today, the eco-park is acknowledged as one of the most successful mangrove reforestation project in the Philippines [1]