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Tianjin Qiaoyuan Park: The Adaptation Palettes

Landscape Performance Benefits

Environmental

  • Improves soil alkalinity in the dry ponds and water quality in the wet ponds as evidenced by field measurements. Soil pH dropped from 7.7 and now fluctuates around 7.2, and water pH levels dropped from 7.4. to 7 or less.
  • Increased the habitat value of the site, with the number of herbaceous plant species increasing from 5 on the existing site to 58 following park construction to 96 two years after the park opened. Ducks, geese, foxes, hedgehogs, rats, and weasels have been observed on the site.
  • Sequesters an estimated 539 tons of carbon in the trees and plants on the site, a service valued at approximately $7,200.

Social

  • Reduces the noise level from 70dB outside of the park to 50dB in the park as evidenced by field measurements.
  • Improves access to green space for the 20,000 nearby residents who can now walk to a park in less than 15 minutes. The park is also served by 26 bus routes.
  • Is a significant destination within Qiaoyuan Park, which is visited by 350,000 people every year, most of whom come from the surrounding communities. Of these visitors, over 50% are senior citizens and 40% are children.
  • Provides educational opportunities for approximately 500 children from nearby schools, with additional students participating in summer vacation programs and regular activities at the adjacent Bridge Museum.
  • Improves ecological awareness and environmental consciousness of park visitors, with 83% of people surveyed saying they approve of the park’s ecological style.

Economic

  • Saved approximately $25,500 in lumber costs by reusing 84.5 cubic meters of old railroad ties in the construction of the observation platforms and bridges.

At a Glance

  • Designer

    Turenscape

  • Project Type

    Park/Open space
    Wetland creation/restoration

  • Former Land Use

    Greyfield

  • Location

    Kunlun Rd & Weiguo Rd
    He Dong Qu

    Tianjin

    Map it

  • Climate Zone

    Cold semi-arid

  • Size

    54 Acres

  • Budget

    14.1million

  • Completion Date

    2008

Through regenerative design, the natural processes of plant adaptation and succession were introduced, transforming a 54-acre garbage dump into a low-maintenance urban park in the northern coastal city of Tianjin, China. The 21 “bubbles” (wet and dry cavities) manage urban stormwater from offsite, improve the saline-alkali soil through natural processes, and allow rich patches of native vegetation to establish seasonally creating a unique, “messy” aesthetic experience. This elegant, ecology-driven solution proves that an unconventional, continuously evolving landscape can create a successful park with strong visual appeal that requires very little maintenance.

  • The project increased public open space in Tianjin by 54 acres, including the wetland space, upland space, and hydrophilic space.
  • 21 pond cavities were created, ranging from 10-40m in diameter and 1.1-5m in depth, with some cavities below ground level and some above on mounds. As they are fed by rains and groundwater, the resulting “bubbles” are a mix of water ponds, wetlands, seasonal pools, and dry cavities with water levels varying seasonally.
  • Urban stormwater runoff, which drains to the site, is retained in some of the deeper ponds where contaminants can settle. In the dry cavities, soils are improved through the wash and filtration effects of seasonal rain.
  • Total park plantings include 40% perennials in 58 varieties and 34% woody plants in 50 varieties. Of these, more than 99% are native species. Plant communities were allowed to evolve and adapt over time, with patches of unique vegetation establishing seasonally with changes is water level and pH.
  • The soil, plants, and limestone were regionally sourced.
  • Nearly 85 cubic meters of old railroad ties were reused in the construction of the observation platforms and bridges.

  • Almost every pond has an observation platform and interpretive signs that describe natural patterns, processes, and native species. These provide opportunities for people to observe, get closer to nature and to learn basic natural science.

Challenge

The 54-acre site had previously been a military shooting range and then a garbage dump, surrounded by slums and highways. Polluted urban stormwater runoff drained to and ponded on the site, with drainage further complicated by several connections between surface and groundwater. The soil was heavily contaminated and quite saline and alkaline, making it a challenging environment for plants. Historically, this coastal region along the Bohai Gulf was rich with wetlands and salt marshes, most of which have been destroyed by decades of urban development. In response to residents’ calls for clean-up of the site, the Tianjin municipal government set out to create a park that would serve the surrounding residents, improve environmental conditions, and require little maintenance.

Solution

A simple landscape architecture strategy was devised, inspired by the adaptive vegetation communities that dot the landscape: Rather than try to restore the site to some historic natural state, natural functions would be reestablished and the dynamic processes of adaptation and succession allowed to occur. Twenty-one pond cavities of varying sizes and depths were carved out, with some below ground level and some above on mounds. Garbage was removed from the site during the earthwork. The result is a mix of water ponds, wetlands, seasonal pools, and dry cavities, which are fed by rains and groundwater. Soils in the dry cavities are improved through the wash and filtration effects of seasonal rains, while deeper ponds capture stormwater runoff and nutrients. Seeds of mixed ground cover and wetland species were sowed initially, and other native species were allowed to grow wherever they took root. Rich patches of vegetation establish seasonally in response to subtle changes in the water table and PH values, creating a low-maintenance, “messy” native landscape and unique aesthetic. Visitors experience the site following red-colored asphalt paths that weave through the palettes with interpretive signs and wood platforms that extend into the ponds and cavities.

  • When compared to the typical cost of weeding, pruning, irrigating, and fertilizing a traditional park, the low-maintenance “bubbles” (wet and dry ponds) save nearly $19,000 in maintenance costs each year.
  • The design of the ponds and use of native plants maintain water quality, requiring only small applications of water treatment chemicals. This saves nearly $5,000 each year when compared to a traditional park’s spending on water treatment chemicals.
  • The design approach to reestablish natural functions and let the dynamic processes of adaptation and succession occur was successful in creating diverse habitats that require minimal management. Key steps in the design process included: careful planning and plant selection, experimentation with species, monitoring of progress during the construction phase as plants became established, and adjusting the design accordingly to achieve the best performance.
  • The interconnected pedestrian paths that surround each of the ponds are a defining feature of the site. However, this dispersed pedestrian network makes circulation, privacy, and group activities challenging compared to a site with more selectively-place trails.

Project Team

Owner/Client: Environment Construction and Investment Co, Ltd, Tianjin City
Landscape Architect:
Turenscape
Architect: Turenscape
Landscape Construction: Tianjin TEDA Eco-Landscape Development Co, Ltd

Role of the Landscape Architect

Led a team of environmental artists and architects from design to construction, unifying the different perspectives into one framework to communicate among the different disciplines.

Case Study Prepared By

Research Fellow: Nancy Rottle, Associate Professor, University of Washington
Research Assistant: Delia Lacson, MLA Candidate, University of Washington
Student Researchers: Peter Cromwell, Ying-Ju Yeh, and Chen Hai, MLA Candidates, University of Washington; Xu Tao and Xiaobing Wang in Beijing
Dec 2011

Topics

Soil creation, preservation & restoration, Water quality, Populations & species richness, Carbon sequestration & avoidance, Reused/recycled materials, Recreational & social value, Educational value, Noise mitigation, Other economic, Educational signage, Local materials, Native Plants, Reused/recycled materials, Wetland, Aging, Placemaking, Restoration

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