A Mother River Recovered--the Sanlihe Greenway

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A Mother River Recovered--the Sanlihe Greenway

The Qian'an Sanlihe Greenway is transformed from former garbage dump and sewage drainage. It stands as an example of how a neglected landscape can be recovered as an ecological infrastructure and everyday landscape with restored ecosystem capacity in providing multiple services, including mediating flood and draught, providing habitats for native biodiversity, integrating pedestrian and bicycle paths for commuting and recreational uses, creating spiritual and aesthetic benefits, and catalyzing urban development. Project Narrative The greenway stretches 13.4 km in length and varies 100-300m in width across the city of Qian'an. It covers approximately 135 hectares and benefits a population of approximately 700,000. Qian'an City is located at the south foot of the Yanshan Mountain, at the bank of Luan River, in the northeast of Hebei Province. Although the main city lies near the Luan River to the west, one cannot see the water since Qian’an’s topography is situated below the riverbed with its high embankment blocking the river view. The river is notorious for its unpredictable flooding, and has thus been kept outside of the city for decades through this high embankment. Meanwhile, as the life source of Qian’an, Sanlihe River has shouldered the long history of the city and carried the collective memory of the inhabitants. Before 1973, the Sanlihe River had crystal clear water from the groundwater recharge of Luan River, which ensured that the temperature of the city stayed cool in summer and warm enough to never ice up in winter. Although frequented by storms and heavy rain, Sanlihe River never experienced disasters of drought and flood in its history, which also provides rich water resources for nearby industries and agriculture, as legendary records witness: "reeds flourish, trees shade, and birds inhabit". However, since the 1970s, the river has been badly polluted by sewage and waste which has resulted from the territory’s continuous industrial development and urban population growth. As a consequence, with the depletion of regional water sources, the Sanlihe River became subsequently dried up and its channel blocked by solid waste. The life source of the city became festered with sores of urbanism, and the hearts and souls of local residents long for its spiritual landscape reincarnation. The landscape architect was commissioned to recover this mother river. The scope of job included sewage management (the redesign of sewage pipes that had previously discharged directly into the river with a passive natural infiltration system), as well as ecological restoration and the urban design along the greenway (although this submission only focuses on the planning and design of the greenway itself) The design strategies are comprehensive and developed across scales: (1) Clean the site: A sewage management system was planned to separate waste water from the urban storm water runoff. As well, organic garbage from the household was used as material to shape landforms, and industrial waste was cleaned and properly treated. (2) A scenic water byway: the design for the greenway took full advantage of the existing natural elevation change between the Luan River bed and the city. A fountain was made through a pipe that goes under the high embankment, so that a constant controlled amount of water will make its way through the city before running back to the Luan River at the lower reach. This strategy turns the Sanlihe into a “scenic byway” of the larger Luan River and transforms the dangerous natural force into a pleasant amenity. (3) Resilient green river strategy: the existing concrete channel of the river was removed, and a multiple water course riparian wetland system was created, including the creation of emerald-like wetland bubble chains at the edge of the main water course which regulates floods and collects and dissipates urban storm water runoff. When the river’s water level drops to its lowest point, pools of water remain in the emeralds as wetlands, creating a “Green River.” Furthermore, these wetlands work as an ecological purification buffer for urban storm water runoff from both sides. These meandering natural waterways, at various surface levels, becomes diverse habitats for wildlife. (4) Tree islands: The existing trees on the site were saved and the riverbanks were transformed into a number of tree islands connected by boardwalks, creating a unique setting for daily activities of the nearby residents. (5) Pedestrian and cycling paths: Along the greenway are the pedestrian and bicycle routes fully accessible to communities along the channel. (6) Landscape guides Urbanism: The greenway is used as catalyst for urban development. High density residential development was envisioned at both sides of the greenway. Immediately after the greenway was built, an enormous amount of new housing development investment was attracted and completely transformed the urban morphology of the city. (7) Low maintenance: The project used low-maintenance native vegetation, lush wetland species, and self reproductive wild flowers for the undercover. The resilient green river strategy allows the water table to naturally fluctuate over seasons. The contrast between “messy” nature and the minimum design of the boardwalk and waterfront platforms turn the big greenway project into an artful everyday landscape. Through only three years of design and construction, this project has transformed this seriously polluted landscape back to its previous splendor as a scenic urban ecological corridor. The mother river has been recovered and the legendary tale narrated by the grandmothers once again rings true: as a place “where reeds and lotus flourish and water abundant with fish and soft-shelled turtles”.

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