In mid 2009 Turenscape was commissioned to design a wetland park of 34.2 hectares right in the middle of this new town, which is listed as a protected regional wetland. The site is surrounded on four sides by roads and dense development. As such, water sources into this former wetland were being cut, and the wetland was under the threat. Turenscape’s strategy was to transform the dying wetland into a ‘green sponge’ – an urban stormwater park, which will not only rescue the disappearing wetland, but will also provide multiple ecosystems services for the new urban community.
The challenges are obvious: How can a disappearing wetland be preserved in the middle of the city when its ecological and biological processes have been cut off by the urban context? How can such an urban wetland ecosystem be designed to provide multiple ecosystems for the city? And what is the economic way to deal with such a big landscape? The solution was to transform the wetland into a multi-functional stormwater park that will collect, filtrate, store stormwater and infiltrate to the aquifer, whilst being productive and life supporting, providing new recreational and aesthetic experiences for the city.
The design strategies are multifaceted and multilayered.
1.Leave the nature core alone: The central part of the existing wetland is untouched and left alone for the natural process to domain for evolution and transforming.
2.Cut-and-fill strategy to create an outer ring. The next strategy was to create a necklace of ponds-and-mounds surrounding the former wetland using simple cut-and-fill technique. This pond-and-mound peripheral ring surrounding creates a stormwater filtrating and cleansing buffer zone for the core wetland, and a welcoming landscape filter between nature and city. Stormwater from the newly built urban area is collected into a pipe around the circumference of the wetland, and then released evenly into the wetland after being filtrated and deposited through the ponds. Native wetland grasses and meadows are grown in the ponds of various depths and the natural evolution process is initiated. Groves of native silver birch trees (Betula) are grown on the mounds of various heights that create a dense forest setting.
3.The path and platforms: On the ground level, following the cut-and-fill water filtration land form, a network of paths are built into the pond-and-mound ring allowing visitors to have a walk- through- forest experience. Seats are put into the ponds to allow people to have close contact with nature.
4.The upper layer above the natural landscape: A skywalk links scattered mounds allowing surrounding residents to have an above-the-wetland and in-the canopy experience. Platforms, pavilions and viewing towers are set on the mounds and are connected by the skywalk to allow visitors to have distant views and observe the nature in the center. Through the transformation of this dying wetland, stormwater that frequently causes flooding has now become a positive environmental amenity in the city. The Stormwater Park now has been listed as a national urban wetland park. This project demonstrates an ecosystem services oriented methodology to urban park design, and is a showcase for this water urbanism approach.