Forest Park ecological wetland - China

Built in 2001, the Kunshan Forest Park is a National Urban Wetland Park covering an area of 166 hectares in the northwest of Kunshan city in Jiangsu province, China. The Forest Park boasts an array of eco-tourism resources and is characterised by parklands, forests and lakes.

The ecological wetland project aims to improve the water quality of five large park lakes by transforming traditional green space into multifunctional green infrastructure which provides water treatment, water recirculation, and extra flooding storage within a versatile landscape. In addition, an ecological restoration zone is planned to protect and remediate the local aquatic and terrestrial habitat, restoring the ecological values and encouraging flora and fauna back to the area.

Kunshan is a polder (a piece of land in a low-lying area that has been reclaimed from a body of water by building dikes and drainage canals) city, meaning it is a low-lying area enclosed by dikes, with no connection to other groundwater sources, except through diverted rivers or engineered canals. Polder waterway quality can be poor and flooding can be an issue in some areas of the city. A strategy was developed to help address this issue by integrating constructed wetlands into precinct parklands to enhance water quality. Canal water would be recirculated through constructed wetlands for treatment, creating a series of open cells within the polder waterway network. The incorporation of these cells has also been used for greater floodwater protection by connecting them as emergency detention basins. The Forest Park Ecological Wetland has been undertaken as a trial to test this strategy.

• Automatic flood relief: The lake system is hydraulically connected to an adjacent waterway by an active gate. If the polder reaches a critical flood level, the gate opens and allows for the Forest Park Lake system to act as additional storage for flood waters.
• Multifunctional landscapes: Forest Park wetlands have been designed to support both water quality treatment and passive recreation within a broader parkland setting.
• Polder water recirculation: Polder water is recirculated through constructed wetlands for greater waterway health.
• Improved ecological value of open space: The forest plantations within Forest Park were reviewed with the objective of enhancing their ecological value. One area within the park was found to support significantly greater bird life than other areas. This was an island that received no parkland maintenance. Pathway and visitation patterns were reviewed accordingly and areas adjacent to the high ecological value island were zoned for ecological enhancement, forming a large area dedicated to habitat and biodiversity. Pathways for pedestrians were downgraded, buffer planting was established, and any parkland style maintenance ceased to reduce disturbance.
• Fish breeding habitat creation: The lakes in Forest Park are mostly excavated waterbodies. Consequently, there is limited natural habitat diversity. The constructed wetland component of the project was going to result in some tree removal, so an opportunity was taken to use the removed trees as large woody debris in the lakes as enhanced fish habitat. Wood debris was carefully located to improve the littoral zone of the existing habitat island and to reduce wave action on the windward edge of the island.

• Parklands can be designed to become multifunctional water management infrastructure, providing both filtration to improve water quality and flood water storage.
• Cleared trees can be utilised for habitat creation providing an important ecological resource while lowering disposal costs.

The principles of this case study can be applied anywhere.