Shenzhen’s Sponge City Soaks Up Rainwater
Urban villages, 1000 almost, provide affordable housing for about 50% of Shenzhen’s residents, most of who are migrant workers and young graduates. Nearly all of them rent and the high demand for housing means concrete residential buildings take up most of the space leaving little room for parks or gardens. And when it rains, with so few permeable surfaces to absorb rainwater, their homes and living areas are vulnerable to floods.
The Green Cloud project is turning this around. Due to the lack of available space on the ground, in its first pilot the project uses largely unused rooftop space on a residential building. Through a simple, replicable roof renovation that involves planting vegetation, the concrete surface of the pilot building is transformed into a “sponge-like” body capable of absorbing and holding rainwater, while expanding greenery. The three-dimensional light steel structure carries over 410 plant containers filled with indigenous plants from Shenzhen’s coastal region, recreating the original natural habitat of the city and enhancing biodiversity in the area.
This rooftop garden is a prominent example of the “Sponge City” initiative, a Chinese national policy framework that focuses on sustainable urban stormwater management. In 2016, Shenzhen became a pilot city for the initiative, ever since working to help urban communities in Shenzhen become more resilient to urban flooding. The availability of empty rooftops is a largely untapped resource, making them perfect for installing green infrastructure. The rooftop garden includes the installation of a rainwater collection barrel, with the pilot village now retaining over 65% of the rooftops’ rainfall, and absorbing, purifying, storing and reusing the rainwater. The green roofs also help regulate room temperatures within the building, reducing the urban heat island effect, improving air quality, and lowering greenhouse gas emissions.
The initiative has the ambitious goal of absorbing 80% of Shenzhen’s urban areas’ rainwater and re-using at least 70% of it. Despite initial distrust, once residents learned what the rooftop garden was for, their attitudes drastically changed. These days, neighbours are friendly, often asking questions about the plants in the garden, and with some even able to see the little green hill on the rooftop from outside their apartment windows— a rare sight in an urban village.
A simple way to cook beetroot leaves using fennel
- 2 bunches beet greens, stems removed
- 1 tablespoon extra-virgin olive oil, or to taste
- 2 cloves garlic, minced
- ¼ teaspoon crushed red chilli flakes
- 1 tablespoon of toasted white sesame seeds
- A small handful of fennel
- Salt to taste
- Freshly ground black pepper to taste
- 2 lemons, quartered
Steam the beet greens, until tender about 4 minutes. Drain in a colander, then immediately immerse in ice water for several minutes until cold to stop the cooking process. Once the greens are cold, drain well, and coarsely chop.
Toast the sesame seeds until brown, in a small skillet stirring all the time and being careful not to burn. Heat the olive oil in a large skillet over medium heat. Stir in the garlic and red pepper flakes; cook and stir until fragrant, about 1 minute. Stir in the greens until oil and garlic is evenly distributed. Season with salt and pepper, and cook just until greens are hot; serve with lemon wedges and the freshly chopped fennel on top.