‘Sponge Cities’ and urban drainage design in Ancient China
Come along and hear about ingenuity in water management and drainage design on Water Industry Night 2019! It is an international water journey through time and off the beaten track, to countries such as Oman, Peru, Argentina, England, Chile, Italy and Denmark – without having to pack! Register now!
To warm up, let’s fly to China to discover the shining points of its water management actions (with the first records of local flood control dating from thousands of years ago)!
China faces urgent water and environmental issues from urban flooding that is becoming more frequent and severe (Jiang et al., 2017). Massive floods have affected more than thirty cities in China during summer 2016 which killed 300 people, forced more than half a million inhabitants to evacuate, and resulted in losses of at least US$ 44.7 billion (Shepard, 2016).
Many factors contribute to these severe flood disasters in China, including global climate change, rapid urbanization and unsustainable urban development (Jiang et al., 2017).
- More extreme rainfall events, particularly high-intensity and short-duration rainfall, proved to play dominant roles in contributing one third of China’s total precipitation (Sun, 2012);
- China has expanded its urbanized area extensively from 1.3 × 104 km2 to 5.2 × 104 km2 between 1990 and 2015. (NDRC, 2016); and,
- Landscapes in developed areas have dramatically changed: the impervious surface area has increased at an annual rate of 6.5%, with the continuous losses of aquatic ecosystems such as lakes and wetlands. (Ma et al., 2014).
To tackle the issue, China launched a policy initiative termed ‘Sponge Cities’ in 2014.
A Sponge City is designed to improve the capacity of cities functioning like a sponge that absorbs rainwater during rainfall events, via implementing a network of permeable surfaces and ‘green-blue’ infrastructure options, which including vegetated rooftops, raingardens, wetlands, and stormwater re-use systems (SC 2015).
Yanweizhou Park in Jinhua (eastern China), completed in 2014, serves as an example of how city spaces can ‘absorb’ water and serve as engines for tourism, city greening and urban wellbeing (Source: E2Designlab).
Urban drainage design in ancient China
Urban drainage design facilities have a long history in China. From the 13th century Lijiang Town (northwest of Yunnan Province) has built a unique water supply system, with a reservoir, spillway, water distribution network, weirs, gates and sluices, and spring collection works. Lijiang Town was assigned to the UNESCO World Heritage List, noting that it “possesses an ancient water supply system of great complexity and ingenuity that still functions effectively today” (Koenig & Fung, 2010).
Another ancient city Ganzhou, located in a low lying basin, has prevented flooding for thousands years, owing to the presence of an ancient drainage system (Source: Xu et al., 2018). The ancient drainage system consists of:
Ancient city walls: when the river level rises threatening the city safety, a door set inside the wall gate is closed to prevent the intrusion of river (hence the name “water door”).
Fushou ditch: the rainwater first enters the open channels and then the Fushou ditch from the drain holes in the open channels. When the river level is high, the water window is closed automatically because of the river pressure; when the river level is low, the water window is opened under the action of water flow.
Ponds: once the river level is high and water window is closed, the trapped water in the city cannot be drained into the river. At such times, ponds can be used to collect and store the trapped water.
(Source: Xu et al., 2018)
‘Ancient Beijing Soakwell‘
A hidden drainage system in Beijing was first built in 1417, which consists of an underground circular culvert system and inverted trapezoid bricks, contributing to the rapid infiltration of rainwater. During a heavy rain, the water flows into the culvert and infiltrates into the soil through the spaces between the bricks. All surplus water is collected in the culverts and subsequently flows away (it’s very similar to what we have now – groundwater soakwells).
(Source: Zhang et al., 2019)
‘Tang Dynasty drainage system‘
Chang’an Town of Tang Dynasty (619-907) had a unified drainage system. A section of culvert was discovered while a set of water gates were installed every few sections to prevent erosion.
(One section of pottery pipe decorated by beast-head-shape. How cute it is~~~)
(Source: Du and Zheng, 2010)
To sum up, ‘Sponge Cities’ and Ancient Chinese urban drainage design share the same visions with Water Sensitive Urban Design (WSUD) in Australia, low impact development (LID) in the US, and sustainable drainage systems (SuDS) in the UK, through integrating water cycle into urban design yields multiple environmental benefits and builds city resilience!
Du, P., & Zheng, X. (2010). City drainage in ancient China. Water Science and Technology: Water Supply, 10(5), 753-764.
Jian-Qi, S. U. N. (2012). The contribution of extreme precipitation to the total precipitation in China. Atmospheric and Oceanic Science Letters, 5(6), 499-503.
Jiang, Y., Zevenbergen, C., & Fu, D. (2017). Understanding the challenges for the governance of China’s “sponge cities” initiative to sustainably manage urban stormwater and flooding. Natural Hazards, 89(1), 521-529.
Koenig, A., & Fung, S. C. C. (2010). Ancient water supply system of the old town of Lijiang, Yunnan Province, China. Water Science and Technology: Water Supply, 10(3), 383-393.
Ma, Q., He, C., Wu, J., Liu, Z., Zhang, Q., & Sun, Z. (2014). Quantifying spatiotemporal patterns of urban impervious surfaces in China: An improved assessment using nighttime light data. Landscape and Urban Planning, 130, 36-49.
National Development and Reform Commission of China (NDRC), 2016. Strengthening urban drainage and water logging prevention infrastructure development to support transformative urbanization. News Brief. The National Development and Reform Commission, Beijing.
Shepard W. (2016). Massive floods cost China $44.7 billion so far this year; ‘ruthless’ urbanization takes its toll. Forbes, 28 July 2016.
State Council (SC) (2015) The general office of the state council advice on promoting construction of sponge cities. GOSC75. The State Council, Beijing.
Xu, Y. S., Shen, S. L., Lai, Y., & Zhou, A. N. (2018). Design of sponge city: Lessons learnt from an ancient drainage system in Ganzhou, China. Journal of hydrology.
Zhang, L., Yang, Z., Voinov, A., & Gao, S. (2019). Nature-Inspired Stormwater Management Practice: The Ecological Wisdom Underlying the Tuanchen Drainage System in Beijing, China, and Its Contemporary Relevance. In Ecological Wisdom (pp. 89-109). Springer, Singapore.