Improved water quality

The Ningbo Ecological Corridor is a post-industrial landscape ecological reconstruction project. It is located in the middle of the Eastern New Town in Ningbo, with a total area of 90 hectares [4]. Built upon a typical post-industrial site with degraded ecologies that needs to be healed and would soon become part of a new urbanized district, this project is holistic ecosystem services-oriented, introducing terraced wetland to manage elevation change of the site to slow the flows of urban runoffs from the street down to the river and remove the nutrients [1]. “Before being designed, the site and surrounding areas were fragmented farmland, villages and factories that were planned to be relocated - a typical brownfield in the rural-urban fringe of the southern region of China”[1]. With the implementation of the project, "the original channelized river is transformed into a meandering eco-friendly waterway dotted with tree isles to increase the interface between organisms and water bodies to empower the river’s purification capacity. The project uses productive crops and annual flowers that are rotated to bring seasonal surprise and agricultural vitality to the growing city. Boardwalks are designed to allow visitors to have intimate experience of nature and the nostalgic pastoral landscape. Pavilions made of corten steel floats on wetlands and terraces, giving the ecological corridor a touch of contemporary urban life and art. [1] "As a result, this project demonstrated landscape as an ecological infrastructure that heals the degraded ecological system meanwhile provides social and cultural services to the establishing communities." [1]

St Inez creek was an ecologically functional tidal waterbody in Panaji, Goa. Panaji has been identified as one of the most vulnerable coastal cities from floods due to the predicted sea-level rise. St Inez creek is one of the very important freshwater bodies in the city because of its cultural, social and biodiversity value. Recently, the ecological functionality of the creek was severely compromised through a combination of natural degradation and anthropogenic influences, which includes sedimentation, collapsed embankments, eutrophication, weed growth, pollution, the release of raw sewerage from neighbouring informal settlements and dumping of construction debris. The current intervention is about the restoration of the creek to conserve the urban nature and ecological systems and to increase the resilience of the city. [1, 2]

Touted as a long-term solution to flooding of Mandaue City, establishment of a mangrove eco-park has begun, having received funding from the Department of Budget and Management (DBM) (Ref. 1). Through establishment of mangroves, the eco-park will "perform a significant role in shoreline protection, acting as a buffer against strong winds and waves", which is considered particularly important in light of the anticipated effects of climate change (Ref. 6).

A total 17-hectare plot is to be rehabilitated, as identified in the Mandaue City Government's Comprehensive Land Use Plan (Ref. 3). At present, it is unclear whether nature-based solutions (including mangrove restoration) are to be implemented across the entire 17ha of the site, but initial efforts have been focused on the restoration of a 5-ha section of mangrove forest (Ref. 2). Due to the lack of data on how exactly the remainder of the 17-ha area will be restored, the total NBS area for this project has only been recorded as 5-ha (5000m2) within this case study, rather than the entire 17,000m2 which is encompassed within the site.

The site is situated at the outfall of the Butuanon River which frequently overtops as a result of heavy rain and has been considered "biologically dead" since 1992 (Ref. 7). The site itself comprises a former dumpsite which had been "left derelict and filled with piles of trash", hence in addition to reducing flood risk, its rehabilitation will serve as green space in which "the residents of Mandaue City [can] gather and enjoy a breath of fresh air" (Ref. 2). The eco-park is considered to bring the added benefit of filtering water as it enters the Mactan Channel, in addition to reducing greenhouse gas emissions through carbon dioxide absorption (Refs. 1 & 6).

The Porsuk Stream divides the city of Eskişehir into two with a green corridor running along the shores of the stream. The Porsuk Stream served provisioning services and acted as a recreational area in the first half of the 20th century, however with increased industrial activities discharging untreated wastewater into the river, rapid urbanisation in the city and other settlements, and increased fertilisers and pesticides in the groundwater originated from agricultural practices (upstream of the Porsuk River), it became highly polluted and its ecosystem degraded severely (1,2,4,5). The Organization for Security and Cooperation in Europe (OSCE) identified the stream as one of the highly dangerous rivers in terms of pollution and health, where no living beings except viruses live (1).
Within the framework of the 'Eskişehir Urban Development Project' the 'Natural Disaster Loss Reduction Project (Porsuk Project)' has been initiated focusing on the ecological restoration of the stream, improving water quality, increasing the resilience of the city against natural disasters (as earthquakes and floods) while also reestablishing the stream's environmental and social role in the city (1). A network of natural infrastructure was created along the Porsuk by expanding public green spaces and link the entire corridor with a sustainable public transport network. (4,5)

Kaysone experiences severe flooding events on an annual basis due to its location to the banks of Mekong river, as well as periodic storms, and past responses to these threats have focused on the Savanxay Market and the Southern Flood Gate, but with limited success (Ref. 1). This intervention focuses on the development of an integrated adaptation plan for the area around the market and adjacent to the Mekong canal. This plan includes NBS-specific components considering how the market's parking area provides an important opportunity for bioengineering and green cover, and that there is "an opportunity to use adjoining land as a constructed wetland and park for recreation, flood retention and storm water treatment" (Ref. 1). The adaptation plan comprises seven points overall, focusing on wastewater recycling, walking paths, proper drainage and green space in addition to an educational component related to climate change and its impacts (Ref. 1).

The Gangxia 1980 green roof, a pilot of the Green Cloud project, was launched by The Nature Conservancy (TNC) in collaboration with key partners, including: Zhubo-AAO; Glocal Estate Management; and Urban Planning & Design Institute of Shenzhen (UPDIS) [1]. Located on an old building in Gangxia village in Shenzhen, the project utilizes three-dimensional light steel structures that are simple to construct and have the capacity to hold over 420 plant containers, filled with plants mostly native to Southern China [1, 2]. The original concrete rooftop is transformed by vegetation, which is capable of absorbing and preserving rainwater, creating a nature-based stormwater management system for the residential building, achieving a 65% of run-off control rate [1, 2]. As a result, a living “green cloud” is formed on a rooftop of Gangxia village, showcasing “a model to improve the urban village’s stormwater management system and its living environment” [1. p.33].

Hatirjheel area development project is a wetland restoration project that explores the possibility of reintroducing water edge elements into the city of Dhaka. The project includes both engineered infrastructure and NbS. The restored jheel (wetland) and Begunbari khal have improved storm-water management of Dhaka and made aquatic biodiversity better. It also increased green and open space in the busy capital. The intended objective of the project was to create a bridge between the densely developed old part of the city on the south and the new organised north part of the city. Spreading over 311 acres, this project has endeavoured towards improving connectivity between major urban corridors as well as acting as a retention pond to mitigate the flash flood-prone densely populated part of the area. [1,2]

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).