Sponge Greenway: Ningbo Eastern New Town Ecological Corridor (Phase III)

The Sponge Greenway was built upon a typical post-industrial site with degraded ecological function that was slated to become part of a new urbanized district. The holistic, ecosystem services-oriented project introduced terraced wetlands to slow the flow of urban runoff and remove pollutants. The original channelized river was transformed into a meandering, ecologically functional waterway dotted with tree-covered islands to increase the interface between organisms and the water bodies, in order to boost the river’s natural purification capacity. Crops and flowers are rotated to create a sense of seasonal surprise and agricultural vitality within the growing city. The project’s boardwalks are designed to bring visitors closer to the natural landscape. Pavilions made of corten steel float on the wetlands and terraces, lending a touch of contemporary style to the ecological corridor. This project demonstrated that an engineered landscape, as a kind of ecological infrastructure, can heal the degraded ecological system while providing social and cultural services to the neighboring communities.

1 Site and Challenges
The Ningbo Eastern New Town Ecological Corridor (Zhongshan Road-Railway) is 1286 meters long from north to south and 434 meters wide from east to west, with a total area of 37.4 hectares. The completed section is between Zhongshan Road and Baizhang East Road, with a north-south length of 470 meters and an east-west width of 470 meters, totaling 12.2 hectares in size.

Located at 29°51′14″N, 121°37′14″E, the site is bounded by Zhongshan Road on the north, railroad tracks on the south, Fuqing Road on the west, and a planned road on the east side. Before being designed, the site and surrounding areas were fragmented farmland with villages and factories that were scheduled for relocation. The terrain was quite flat and the water network was seriously polluted by industry and domestic sewage. The river had been partially straightened and channelized. Factory buildings, together with cement paving and stacking materials left by the rural enterprises, were scattered throughout the site. Domestic and industrial waste filled the river channels. This site was a typical brownfield in the rural-urban fringe of the southern region of China.

2 Objectives and Design Strategies
This is a post-industrial landscape ecological reconstruction project. As part of the larger ecological network in the Ningbo Eastern New Town, this project aims to improve the continuity and integrity of the ecological corridor while fulfilling the needs of the communities surrounding the site. Oriented toward holistic ecosystem services, the landscape is intended to function as a comprehensive ecological infrastructure to systematically solve the existing urban ecological and environmental problems. The project was intended to restore the hydrologic environment, clean local water bodies and rebuild riparian wetlands, while creating a public green space to meet the needs of local residents and help shape the identity of the new urban district. The project is intended to bring vitality and a sense of place to the growing city, and to enhance citizens’ sense of belonging and community. The project is also intended to achieve long-term savings in construction and maintenance costs.
To meet these objectives, the project adopted the following four strategies:

2.1 Preservation, reuse and regeneration: factory buildings, trees and water systems
First, the current factory buildings in the site are preserved to maintain the site's historical context. The existing trees and water system are also retained and integrated into the new design. In the future [or “in a future phase”], the grid structure of the factory buildings will be transformed and interspersed with green planting to form a unique landscape and place for relaxation, making it the landmark of the entire project.

2.2 Terrain design based on hydro-ecological processes: terraces, curved banks and islands
Terrain design aims to improve hydro-ecological processes. It slows the water flow, intercepts contaminants and purifies the water body, and makes full use of plants to absorb nutrients from water bodies. Based on the original path of the river, the corridor is ecologically designed in a curvilinear form. The islands are strategically placed to increase the interface between water and land. With an elevation change of 4 meters between the road and the river’s water level, multi-level terraces are designed to intercept and filter the urban surface runoff before it flows into the river. To strengthen the water purification process, a diversion channel was designed on the west side of the site. Contaminated water from the upper reaches of the river is lifted into the diversion channel, which meanders through the forest, distributing water to each terraced wetland for filtration and purification, before the water is ultimately discharged into the river.

2.3 Diverse vegetation: wetlands, crops and woods
The vegetation design is divided into three types: wetland vegetation, annual crops and meadows, and woods. Low-maintenance aquatic plants and wetland plants are widely used on both sides of the riverbank and in the water. On the side closest to the city, arbor belts dominated by broadleaf trees such as Cinnamomum camphora, Ginkgo biloba, and Elaeocarpus decipiens form a green border between the city and the park while creating a semi-transparent visual connection in between.

On the islands, densely planted Metasequoia and Cyprus groves divide space in the middle of the ecological corridor. The roots of the trees penetrate into water body to absorb nutrients and purify the water.

On the terraces between the wetlands and arbor belts, annual crops and flowers are planted in season, including canola in spring, sunflower in summer and chrysanthemums in autumn. The changing plants bring a seasonal rhythm and sense of change to the city, providing the new generation of urban residents with a chance to reconnect with farming and nature. In contrast with other cities built on stereotyped plans, the urban area in Ningbo Eastern New Town has been refreshed by a pleasant vitality.

2.4 Immersive experiential facilities: boardwalk and pavilions
Continuous footpaths and cycling paths run through the ecological corridor and connect with the city’s broader greenway system. A boardwalk system, connecting the city and going through the wetland, groves and terraces, provides various opportunities for immersive experiences. Several wooden platforms are embedded in the wetlands and terraces, or interspersed with trees. The platforms are also combined with pavilions, embellished on the landscape matrix. The pavilions are made of folded corten steel. They are both art installations and shelters, inviting people to relax and linger. They have become the visual highlight of the ecological corridor.

3. Accomplishment：Providing holistic ecosystem services
Phase III of the Ningbo Ecological Corridor was completed in 2016.The waterway has been revived with rich native habitats, and functions as a flood-resilient green sponge that can cleanse the contaminated water. The seasonal agricultural landscape and rotating meadows provide a sense of surprise to the city’s citizens. Although local residents intensively use the corridor year-round, the high time is when the canola, sunflowers and other flowers are in blossom. Then, hundreds and thousands of local residents and tourists from afar are attracted to the corridor, bringing a sense of infinite vitality to the city. As an important part of the overall ecological corridor, the park was named “Most Beautiful Greenway in Zhejiang Province" by the Urban and Rural Construction Department of Zhejiang Province in 2019.