Sponge City Is Transforming Urban Flood Management

By Dr. Faith Chan, Dr. Dimple Thadani, Lei Li 24 September, 2021

Dr. Chan, Dr. Thadani & Li explain how Sponge city program (SCP) combat urban flood risks in China & the social media's role

Urban floods in Chinese cities

Urban floods have been a major concern due to climate change and irresistible urbanisation in Chinese cities, which escalate threats to our daily life.

China incurs the highest flood damages only followed by USA and India, more than 351 Chinese cities experienced urban floods in the last decade (from 2008 to 2010). We evidently witnessed severe urban floods in some Chinese megacities recently, such as Beijing (2012), Guangzhou (2014, 2015), Shenzhen (2014), Ningbo (2013) and Wuhan (2016).

China incurs the highest flood damages only followed by USA and India…

…351 Chinese cities experienced urban floods in the last decade

Sponge City Program – transforming urban stormwater management

The Sponge City Program (SCP) was initiated in 2013 by the Central National Government (CNG) during the congress of the 13^th Five Year Plan. The SCP is a new concept addressing urban floods through accumulation, purification, storage, and reuse of rainwater.

SCP aims to improve the urban flood protection for 1-in-30 years floods

The SCP is exploiting soft-engineered measures from Blue-Green Infrastructure (BGI) and Low Impact Development (LID) (e.g., via raingardens, bio-swales, artificial wetlands, ponds, and permeable pavement), aiming to improve the urban flood protection standard reaching at 1-in-30 years return period that aligns with other Asian major cities standard (e.g. Tokyo, Hong Kong and Singapore closely aligned) (See 2 photos below).

30 cities across the country in different climatic zones and regions have been selected as sponge cities including some familiar names such as Ningbo, Hangzhou, Shanghai, Beijing, Shenzhen and Wuhan, etc. have been selected as the Sponge cities.

Diagnose – current progress in SCP

The target of SCP is indeed very ambitious according to national guidelines. By 2020 (last year), it is required that about 20% of urban areas are covered by the SCP infrastructure. Looking forward, we expect that about 80% of urban areas should absorb and re-use at least 70% of rainfall under the CNG’ SCP guideline and targets that expect all 30 Sponge Cities to achieve this towards the end of 2030s.

SCP is very ambitious…

…yet the public has doubts over its effectiveness & cost-benefits

Nevertheless, doubts and uncertainties have been raised regarding the effectiveness of SCP on urban flood control. For example, ‘Pilots of 30 sponge cities nationwide, 19 cities experienced flooding this year’, “Nanfang Daily: We must return to rationality in the face of sponge cities”, “Current Commentary: Wait a minute to criticize the construction of sponge cities”, ‘The SCP must tolerate the doubt to water’. The public started to cast doubts over the program effectiveness, question whether it is cost-beneficial, and worry that the program cannot protect them from stronger and more uncertain floods due to climate change.

In our current research project that led by Dr Chan and Dr Thadani, we aim to explore the perception and understanding of SCP from communities and stakeholders in Sponge Cities, such as Ningbo, Wuhan, Guiyang, Shenzhen, etc. Interestingly, our research team have found that the factors of intellectual elements (including cultural shift and perceptions change) from practitioners, developers and public are related to social acceptance and perceptions of the SCP implementation.

A better perception could help formulate pro-SCP policies

Normally, a better perception of the SCP could help formulate pro-SCP policies and deliver the according practices easier. That will also enhance multiple benefits, such as facilitating updating engineering standards on improving the Sponge City infrastructure and potentially foster markets to establish BGI stewardship system (e.g. SCP performance assessment standard or similar benchmarking/certification systems) to make the program sustainably better towards longer-term.

Social media is effective for the public to understand SCP…

Scientific papers published research findings of SCP, but that could be very challenging for the general public to comprehend. Social media (including new media) thus becomes an effective channel for the public to share information, their personal viewpoints and opinions.

…it also allows stakeholders (e.g. govt planners) to understand what the public is thinking

Social media is also a good outlet for relevant stakeholders (e.g. governmental planners, water engineers, environmental officers, urban forest engineers, civil engineers, etc.) to recognise and understand the expression and concern by the communities and public in the Sponge cities (via sharing and commenting on reports, newspapers, on-line blogs, etc.) so as to improve and better transform the SCP practice.

For the Chinese culture, we are fully aware our ways of communication are slightly different from the Western world, which is normally affected by the great affection by Confucius (Kofuzi/Kongzi) thinking. Therefore, understanding mindsets, behavioral actions and reactions/responses and communications via the influence of social media (e.g., unawareness, misunderstanding, resistance and fear to innovative BGI and SCP facilities) are significant as these are subtle factors influences policymakers, developers, water engineers and public to understand and support the implementation of SCP/BGI.

Govt & experts have communicated SCP at a good level of scientific knowledge via media

In particular, Li and Chan found the government and experts have been digested and communicated the purpose and progress of SCP at a good level of scientific knowledge (of SCP definition, construction, functions, targets, deliveries and future prospects, etc.) via media (e.g. online and offline newspapers, blogs, etc.) through the last few years, after their analyses of over 350 news articles across the country.

Municipality govt of sponge cities are determined to transform & educate the public

That illustrated the municipality governments of Sponge Cities are determined to demonstrate their commitments and intentions, not only addressing urban floods by using environmental friendly measures under SCP, but also hoping to transform and educate the public and according communities. That will be helpful to increase their perception and engagement, prior to improving the social preparedness and responses for better urban flood resilience delivery. In light of the COP 26 upfront, public participation, engagement and involvement seem again the wise and effective choice reducing future urban flood risk in Chinese cities.

Looking ahead

Our research has found that there were some successful SCP projects established in Shenzhen, Wuhan, Beijing, Ningbo, and other Sponge Cities. It is possible to tailor our ideas and approaches to the Chinese cities on improving the urban flood resilience in SCP via better communication and the efforts from social media (include new media such as Tik Tok, WeChat, etc.).

Some municipal govts (e.g. Ningbo) have set up a new media channel for the public to express opinions

No doubted that there are still many technical guidance and management issues for the broadcasting and communication between the stakeholders and non-stakeholders (among all actors) are indeed necessarily to be overcome and improved in the nearly future. But some municipal governments (such as Ningbo) have already positively undertaken the practice setting up the new media channel (e.g. WeChat account and the e-point express site) for the public and communities to express their opinions.

We start to see an increasing policy change driven by the public & media

In fact, the use of social media helps and transforms the public and stakeholders’ perception, in prior facilitates the communication between communities, engineers, decision-makers and developers to improve the effectiveness of current and future SCP implementation. We seem to start to see the rainbow on an increasing policy change driven by the public and media, which is a large step ahead in terms of public participation and engagement in the Chinese way.

We also need to be fully understood that the social-political systems in China is different compare to the Western world, then that could be another question of pushing the Chinese Sponge Cities to achieve very high degree of public participation (e.g. citizen empowerment) whether will cause the best benefits to everybody in terms of better delivery of future practice.

Everything needs time to build and progress, we have evidently seen the municipal government has tried hard to inform, explain and educate about the SCP, but also start to upscale for a better consultation via new ways of thinking, by using social media and new media platforms.

The transformation of urban flood management in Chinese cities is truly significant and more social-concerned compared to decades before only relying on engineering techniques and measures (Chan et al., 2021).

Chinese govt now combines engineering practices & soft measures on flood protection infrastructures

Traditional engineering practices are still vitally important in reducing urban flood risk, but we have seen the Chinese Government moved ahead with the implementation of SCP, delivering multi-functions and inter-disciplinary approaches to address urban environmental issues via soft measures on flood protection infrastructures (e.g. via urban parks, artificial wetlands, ponds and urban lakes). Communities to enjoy these measures by better recreational and environmental benefits (e.g. reducing heat-island effects). Now also start pushing social engagement and involvement with a better communication, which is positive and promising.

Singapore, Berlin, Sydney, & the US are also trying to manage water the eco-friendly way

China isn’t the first to embrace GI, because Singapore, Berlin, Sydney, and the US are trying to manage water the eco-friendly way, except with different names. We expect that SCP could be a new way of thinking about the city of a green future to mitigate climate change and urban floods under similar urban pressures on population growth and urbanisation.

In fact, interestingly, our research also found that some indication of the influence of SCP reflected by media reported from overseas. For example,  “Spongy roads’ to be Slough’s new claim to fame “, “Sponge city making Berlin cooler”, “Sponge City: Berlin plans for a hotter climate”, “Berlin & China Creating ‘Sponge Cities’ — Landscape Architects Help Cities Absorb Water, Cool Down”, “India cities must become ‘sponge cities’ to tackle urban flooding”, “Kochi may be State’s first ‘sponge city’”, which revealed that Sponge City Program and the cases of Sponge Cities have started influencing globally, and turning to be successful “green brand” name that promotes Blue-Green infrastructure and urban green movement branding as a potential international model.

Sponge City Program & the cases of Sponge Cities have started to become a global phenomenon

Acknowledgement:

The research was funded by the Institute of Asia Pacific Studies (IAPS) Research Grant 2019-2021; and the Faculty of Science and Engineering Postgraduate Research Grant 2018/21– University of Nottingham Ningbo China. We appreciate the support obtained from the National Natural Science Foundation of China (NSFC) (41850410497) and the National Key R&D Program of China (2019YFC1510400).

Further Reading

• Frightening New Extremes from Germany to China Demand Strong Actions – Two back-to-back extreme events occurred in Germany & Zhengzhou – different but share “record breaking”. What are they signaling? What does it mean to the world? CWR’s Yuanchao Xu breaks it down
• Looking for water in China’s 14FYP – The new China is not the old China. CWR’s Xu & Tan went searching for water in the 14FYP and are left feeling optimistic, see why in our review
• Water caps & targets – how has China fared and where is it going? – China has set a 2025 water reduction per unit of GDP target. Is it aggressive enough? To answer this we take a close look on how China has fared on its past targets
• Sponge Cities: An Answer To Floods – Floods have cost China close to RMB2 trn between 2000-2014. Today, with 641 cities prone to flood risk, the Chinese govt has turned to sponge city pilots. Do they work? How much do they cost? CWR reviews
• Counting the Costs of Floods in China – With China in the midst of one of its worst flood episodes in history, Asit K Biswas & Cecilia Tortajada look at the significant social and economic costs of floods, and what can be done about them

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