Flood detention at Yongchunpi
Walking out of the Xiangshan Metro station, after a stroll of about 20 minutes we arrive at Yongchunpi Wetland Park, beside the Four Beasts Mountains (Leopard Mountain, Elephant Mountain, Tiger Mountain, and Lion Mountain).
Yongchunpi lies in a natural depression alongside the Four Beasts Mountains. In former times it was a pond used for irrigation, but after World War II it was concreted over and turned into a military base. After the base was relocated, Yongchunpi was repurposed as a wetland park with the dual functions of stormwater detention as a means to reduce flooding, and ecological restoration. The first constructed urban wetland environment in Taipei City, it won the top-ranking Outstanding Award for 2020 from the Taiwan Institute of Landscape Architects, as well as an Award of Excellence at the 2020 Africa, Asia–Pacific, and Middle East (AAPME) Awards of the International Federation of Landscape Architects.
Liu Po-hung, founding principal of the consultancy firm Classic Landscape Design and Environmental Planning, says that there were two main guiding principles in designing the wetland park: The first was a desire to extend the ecosystem of the Four Beasts Mountains into the wetland, while the second was to meet the need for a public park.
“Rivers in Taiwan are short and fast-flowing, so environmental engineering is needed at or near the foot of the mountains to catch rainwater. This is in keeping with the concept of the resilient city.” The creation of the wetland park offered an opportunity to do something along these lines. The contractors dug up the large areas of concrete that had prevented water from infiltrating into the soil, and used the waste material to create hills and depressions of various heights into which they routed the water of the Leopard Mountain Creek, creating areas of open water of varying depths. When it rains heavily, the park functions as a basin that stores and absorbs water. Some 86% of Yongchunpi’s surface area is covered by vegetation or water. The park can store nearly 4,900 cubic meters of water, enough to detain sudden torrential rains for 8.77 hours.
Liu Po-hung also recommends that we visit Dagangqian Park, inside the Neihu Technology Park. It was formerly the site of the Taipei Flower Market, but after the market relocated all that remained was a large expanse of concrete surrounded by office buildings. “The site had no natural water sources, so how could we use it to enhance resilience? We turned it into a park that can store water,” says Liu. As with Yongchungpi, they used the spoil from breaking up the concrete that covered the site as infill to create a rolling topography that forms an integrated stormwater detention and drainage system hidden under the park’s lawns. This has a capacity of 2,900 cubic meters, which is six times the water retention index for the site. “It already exceeds the statutory requirements for runoff sharing, so besides covering its own needs, it also serves as a flood detention basin for the surrounding area.”
Liu Po-hung, founder of the consultancy Classic Landscape Design and Environmental Planning, endeavors to incorporate resilience into his designs in order to make this concept part of citizens’ daily lives.
Yongchunpi, a former military base beside Taipei’s Four Beasts Mountains, has been transformed into a park with the dual functions of stormwater detention and ecological restoration. (courtesy of the Geotechnical Engineering Office, Taipei City Public Works Department)
Dagangqian Park, where the former expanse of concrete has been turned into a green urban space, has large flood detention basins below its surface, putting the concept of resilience into practice.