Perception of sponge city for achieving circularity goal and hedge against climate change: a study on Weibo

Purpose – Global climate change speeds up ice melting and increases ﬂ ooding incidents. China launched a sponge city policy as a holistic nature-based solution combined with urban planning and development to address ﬂ ooding due to climate change. Using Weibo analytics, this paper aims to study public perceptions of sponge city. Design/methodology/approach – This study collected 53,586 sponge city contents from Sina Weibo via Python. Various arti ﬁ cial intelligence tools, such as CX Data Science of Simply Sentiment, KH Coder and Tableau,were applied inthe study. Findings – 76.8% of public opinion on sponge city were positive, con ﬁ rming its positive contribution to ﬂ ooding management and city branding. 17 out of 31 pilot sponge cities recorded the largest number of © Liyun Zeng, Rita Yi Man Li, Huiling Zeng and Lingxi Song. Published by Emerald Publishing Limited. This article is published under the Creative Commons Attribution (CC BY 4.0) licence. Anyone may reproduce, distribute, translate and create derivative works of this article (for both commercial and non-commercial purposes), subject to full attribution to the original publication and authors. The full terms of this licence may be seen at http://creativecommons.org/licences/by/4.0/ legalcodeTheauthors thank Yunyi Mao (Panzhihua University) for his useful contributions and suggestions regarding sponge city.


Introduction
Flooding has become a global natural hazard when climate change speeds up the ice melting in the Antarctic ice sheet (Stokes et al., 2022).It has become a global concern in recent years (Tian et al., 2023).It adversely impacts humans and societies when urbanisation intensifies (Cheng et al., 2022).According to the World Meteorological Organization (WMO) (2022), more than 11,000 water-, weather-and climate-related disasters have been reported, resulting in more than two million deaths, an average of 115 deaths per day and $3.64tn economic losses over the past 50 years.
According to Zha et al. (2021), Zhao et al. (2019) and Nguyen et al. (2019), countries worldwide have implemented various water control measures since the 19th century.France incorporated the urban drainage system into the construction plan in 1852.The UK began to build underground drainage system in 1859.Germany emphasised "zero increase in drainage" in 1990s.Japan promoted the "rainwater retention and infiltration plan" in 1920, and Tokyo built the world's most advanced sewer drainage system since 1992.The USA has constructed large-scale drainage systems since 1972, proposed the low-impact development model in urban construction and enforced "in-situ flood storage".The USA was the first country to research stormwater regulation and storage.Besides, Australia has prevented and controlled urban waterlogging since 1975.In Bangladesh, floating garden generates economic, social and ecological benefits in low-lying areas (Abdullah Al Pavel et al., 2014).
In recent years, China has launched a new national initiative called "sponge city" which enables cities to absorb and save rainwater like sponges (Zhang et al., 2019;Guan et al., 2021) to improve urban resilience.It is a low-impact development rainwater system (Guan et al., 2021) that aims to solve the problem of water storage and waterlogging, reduce water pollution, improve water quality and enhance water ecology (Gu and Cui, 2017;Ji and Bai, 2021).
Although sponge city has become increasingly prominent (Lin et al., 2019), it requires highly collaborative and innovative work (Gu and Cui, 2017).Sponge city construction has many problems and controversies due to high construction costs, a lack of technical guideline, high management costs and low management efficiency (Zhang et al., 2019).Fu et al. (2022) doubted whether sponge cities provided appropriate solutions to China's growing urban flooding problems: it needs all stakeholders' joint efforts (Gu and Cui, 2017).On the other hand, sponge city provides solutions to water hazards and disasters and improves the urban environment and human well-being.Thus, thriving sponge cities enhance urban resilience and city branding (Thadani et al., 2020).Likewise, online social media content reflects the public's perception, content about sponge city affects a city's brand image (Thadani et al., 2020).Thadani et al. (2020) analysed the current application of China's online social media in city marketing and branding based on the sponge city plan.Besides city branding, sponge city construction requires active participation and public support.As Sina Weibo is China's leading social media, public opinion mining could be useful to know more about stakeholders' perception on sponge city.Yet, research on the public perception of sponge city on Sina Weibo is scarce.To fill the research gap, the study analysed data by Python and artificial intelligence (AI) tools to study the public's foci, locations, content and sentiment on Sina Weibo.It provides policymakers with insights regarding the public's main concerns about sponge city.
This paper puts forward the following research questions: RQ1.What are the public's concerns about sponge cities?
RQ2. Are the sponge cities posts optimistics?
RQ3. Has the sponge city concept been efficiently communicated among the public?
The study's objectives are as follows: to visualise and analyse the popular topics and content about sponge city on Sina Weibo; to study the sentiment of Weibo's sponge city posts and the possibility of sponge city to enhance city branding; and to explore the beneficial strategies for government and enterprise about sponge cities based on the public's perception.
This paper offers valuable information to monitor sponge city development policies to address water scarcity and climate change challenges.Besides, it proposes that government departments to address public opinions in social media, which helps them formulate policies, spreads the sponge city concept and encourages residents to participate.This article consists of six sections.The literature review is described in Section 2. The research method is in Section 3; Section 4 describes the data analysis; Section 5 describes the results and discussion; and Section 6 gives the conclusion.With big data and social media analytics, this research offers a new perspective on investigating the public perception of sponge cities, providing insight to the government to improve sponge city communication and brand management.

Literature review 2.1 Global water strategies
Water problems brought by climate change is one of the global challenges in pursuing sustainable urban development (Ma and Jiang, 2022).Countries use different measures to control flooding: sustainable urban drainage systems in the UK (Ma and Jiang, 2022) minimise surface water runoff and flooding risk by mimicking natural water systems such as ponds, wetlands, depressions and basins; water-sensitive urban design in Australia (Ma and Jiang, 2022) installs green stormwater infrastructure that uses facilities to reduce the impact of urbanisation and enhance cities' comfort, ecosystem and livability; and the Active, Beautiful and Clean Plan in Singapore aims to create beautiful and clean streams, rivers and lakes and provide postcard-like community spaces by integrating drains, canals and reservoirs holistically with their surroundings (Tan et al., 2019;Nguyen et al., 2019).  1 shows China's sponge city policies since 2014.In 2015, the Ministry of Finance, the Ministry of Housing and Urban-Rural Development and the Ministry of Water Resource of the PRC jointly issued a document to implement the pilot sponge city and explore the best approach that fits China's conditions.Sponge city has received significant attention and a positive response from the local government.In June 2015, the national government conducted sponge city construction performance evaluation and assessment from six aspects:
In 2015 and 2016, pilot sponge city construction took place in 30 cities in China.According to the Ministry of Housing and Urban-Rural Development of the PRC (2017), China's Urban Municipal Infrastructure Construction "13th Five-Year Plan" proposed that over 20% of urban built-up areas must meet the sponge cities' requirements in 2020 and reach 80% in 2030.In February 2019, sponge city was required to protect the natural ecological pattern.The goals were achieved through retention, infiltration, storage, purification, emission and utilisation (Ministry of Housing and Urban-Rural Development of the PRC, 2019).In 2022, sponge cities construction was included in the "14 th Five-Year Plan", it included 25 sample cities and the central finance provided subsidies to the pilot cities (Ministry of Finance of the PRC, 2022).
The PRC government and municipal departments attach great importance to sponge city and consider the public's safety and health first.Sponge city policy purifies and beautifies the cities, improves city quality and enhances public people's happiness (WU and QIN, 2019).Table 1 shows the strategic plans in China from 2013 to 2022.

Sponge city for climate change in China
The Chinese government attached great importance to adaptation to climate change and has introduced relevant strategies and policies.Owing to climate change, rapid urbanisation, changes in land use and rapid socioeconomic development, surface water inundation was the most severe water-related problem in many large cities in China (Chan et al., 2018).It included extraordinary precipitation in Beijing, Jinan, Chongqing, Zhengzhou, etc.In sponge city research, scholars have studied the future adaptive countermeasures of different cities regarding climate change, especially urban flooding risk resilience.The analysis included Shanghai (Tong et al., 2022), Beijing, Tianjin, Shenzhen (Shao et al., 2021), Guangzhou, Chongqing, Zhengzhou (Tong et al., 2022), Jinan (Cheng et al., 2022), Xi'an (Luo et al., 2022), Nanjing (Liu et al., 2021), Wuhan (Dai et al., 2018) and Xiamen (Shao et al., 2018).Ma and Jiang (2022)  Perception of sponge city planning approach, Li and Kim (2022) analysed sponge city projects' impact on Harbin, Quzhou and Sanya, China.The results showed that current sponge city projects could improve the urban climate's warmth (Li and Kim, 2022).

Sponge city for enhancing water and resources circularity in China
Sponge city development addresses climate change and the water-related challenges of urbanisation (Ma and Jiang, 2022).It solves urban surface water flooding problems and improves urban water resource management (Wang et al., 2021b).Nature-based solutions for sponge city have been promoted as sustainable solutions for urban stormwater management and addressing the urban flooding problem (Fu et al., 2022).To improve the assessment of the hydrological cycle and sponge city's options, Jiang and McBean (2021) used the concept of "One Water" to demonstrate structured thinking about how each dimension of the hydrological cycle could be used to study the degree of interrelationships.Some scholars discussed the relationship among water elasticity, resources, treatment, ecology, waterscape and management modules based on sponge cities to solve urban water problems and human livability (Wang et al., 2021a).Based on the sponge city plan, six critical processes of water circularity include retention, infiltration, storage, purification, emission and utilisation (Liu et al., 2022) are applied in more than 30 cities in China.The increase in urban greening, urban river and lake wetlands expansion, and rainwater resource utilisation have reduced the city's carbon emissions (Shao et al., 2018).Sponge city can benefit from the circularity issues on water and carbon dioxide.

Social mediaa missing piece in sponge city study
Social media has a considerable global user with a diverse geographic distribution; users can quickly and easily post, comment and repost any message; and information can be found and swiftly shared (Cheng et al., 2019).Thus, natural disaster management and prevention rely heavily on social media analytics.Moreover, four metadata fields in social media dataspace, time, content and networkprovide helpful information to understand the situation better and respond to disasters (Wang and Ye, 2018).This can overcome the problem of traditional approaches like questionnaires and interviews, which suffer from low response rates (Li et al., 2022).

IJCCSM
Research shows that while most people are aware of flooding hazards, they lack awareness and understanding of sponge city initiatives (Zheng et al., 2022).Because the effectiveness of implementing nature-based solutions depends on the participation of a wellinformed public, researchers conducted a survey in Wuhan to identify factors that influence public perception of sponge city plans (Zheng et al., 2022).Previous surveys showed that the public's attention, satisfaction and acceptance of sponge cities differed depending on living environments (Luo et al., 2022).Sponge city residents are satisfied with the travel and living conditions and strongly support the local government (Luo et al., 2022).Fu et al. (2022) believed that bottom-up community-based approaches are essential to transform sponge cities into flood-resistant ones.
The role of social media in affecting public perception of sponge city was remarked to a different degree.Taking Xi'an China as an example to compare awareness differences of sponge city, Zheng et al. (2022) stated that the concept of sponge city was one of the few ways for locals to come across them because it was occasionally mentioned in social media and is not often visible in the streets.Cheng et al. (2019) pointed out that during the flooding, the public questioned the efficacy of sponge city investments on social media (Sina Weibo), negatively impacting the mitigation and recovery stage of the flooding disaster.
Sponge city has received public attention for over 10 years (Yin et al., 2021).Although the above studies highlighted people's perceptions, they adopted offline public and community data.Most focus on sponge city's construction, technical aspect and management method.Research about public perceptions of the semant analysis and foci of sponge city is scarce.Thus, there is a research gap in public perceptions about sponge city's foci and sentiment on social media.

Ecological modernisation city branding and social media
City branding refers to research and management of brands that represent cities which include the research of several branding relevant concept (Molina et al., 2017).A comprehensive understanding of the current city image is the main concern in the first step of city branding (Shirvani Dastgerdi and De Luca, 2019).According to de Jong et al. (2018), the ecological modernisation city labels like resilient city and green city appear widely in the academic research and policy and are frequently adopted for promoting ecological modernisation.Sustainability as an additional dominant city-branding narrative has increased in prominence as a result of the discourse on sustainable development (Rinaldi et al., 2021).Cities reflect imperative of ecological modernisation in the branding practices by responding to the ecological modernisation requirements (de Jong et al., 2018).
The way cities can and should communicate and build their local brands has changed, thanks to the internet and its tools, as social media networks allow users to generate the brand content.Social media platforms may be one of the most visible aspects of online branding strategies (Molina et al., 2017).

Research method
Recent research has shown that social media is increasingly being used to respond to crises.Using big data and social media to improve flooding preparation and prevention significantly reduced flooding impacts (Chan et al., 2022).Social media is used for disaster preparation, response, mitigation and recovery (Tang et al., 2015;Carley et al., 2016;Cheng et al., 2019).Despite there is an increase in research on using social media in times of different disasters, and there is rare relevant research in China (Cheng et al., 2019).
From 1st January 2011 to 17th September 2022, the study collected Sina Weibo users' information about sponge city (in Chinese "海绵城市") via Python 3.10.Then, the KH-Coder and CX Data Science of Simply Sentiment were applied for the semantic analysis of Sina Weibo content.The cluster analysis uses the statistical technique, and the frequency of coword occurrence studies the co-occurrence network and the relationships between various groups.A research field can be inferred intuitively from multidimensional scaling analysis, which determines the topic structure by calculating the distance between topic words (Li et al., 2023).Clustering is accomplished using the KH Coder.This study also reviewed sentiments expressed in the posts via AI into categories like opinions, facts and positive and negative (Song et al., 2022).The method flowchart is shown in Figure 1.
There were 64,693 contents from Sina Weibo's users.After selecting, cleaning and deleting the data not related to "sponge city", 53,586 data were collected.From 2011 to 2016, the government put forward the concept, method and standard of "sponge city".Thus, sponge city microblogs increased and peaked at 8,589 blogs in 2016, with comments recorded high in the same year (data for 2022 is incomplete).The number of likes 151,718 peaked in 2021, which was several times higher than others (Figure 2).

Data analysis 4.1 Keywords analysis
After running pre-processing in KH Coder, there are 53,586 paragraphs and 351,375 sentences.When we selected words to analyse, keywords such as sponge city, city, and sponge cities were deleted to enhance popular topic visualisation.This study also included stop words for keywords like the pronoun, prepositions, etc.
4.1.1Word frequency.This study visualised the top 300 keywords via Tableau 2021.3.Top 50 keywords with higher frequencies are shown in Table 2. From Figure 3, the font size indicates the total number of term frequencies.Among them, water (67,087), construction (66,488), urban (55,944), road (37,952), new (37,925), development (36,049), ecological (28,855), "park" (28,282), "project" (27,752), "green" (27,482), area (27,387), projects (21,906), district  water safety, resource, environment, ecology and culture.These five topics are the main factors affecting the urban water system in the urban water cycle (Table 3).4.1.2Co-occurrence network.Constructing a word co-occurrence network helps analyse the relationship between words and words that appear together in a sentence.The minimum word frequency was set as 5,000, and the minimum document frequency was set as 1.The co-occurrence network is shown in Figure 4. Thirteen clusters focused on three topics: (1) sponge city's construction; (2) ecological environment and urban-rural development; and (3) management by municipal departments and enterprises.
The most significant cluster is water, construction, urban, new, green, area, road, project, district, build, squire, meters, kilometres and space.It is represented by dark blue colour.The largest cluster also links to the cluster in orange, and the second cluster with development, management, promotion, housing, urban-rural and system.The biggest cluster relates to the third cluster with green colour, which includes ecological, park, environment, improve, quality and improvement.4.1.3Parts of speech.Figures 5 and 6 show the most frequent adjectives and verbs.Municipal represents that the many blogs are related to governments' systematic planning, report, commitments, implementation, projects, etc.The word "Natural" were usually mentioned: "Natural resource", "Natural Sponge", "Natural surroundings", "Natural accumulation", "Natural purification", "Natural process", "Natural ecological security", "Natural storage", "Natural ecosystems", "Natural disasters", "Natural aquatic organisms", "Natural cycle of water", etc. Natural methods construct a sponge city, and it is based on "Natural ecological security" and "Natural surroundings".

Content analysis
This study studied the annual most-liked blogs related to sponge city from 2013 to 2022.As abovementioned in Section 3, the most like posts happened in 2021.Sponge city microblogs Water safety "purify water", "water control", "water treatment", "water replenishment", "water storage", "water collection", etc The shortage of drinking water resources and the severe decline of agricultural water and groundwater have issued more serious warnings!For example, User A posted a blog about developing sustainable circular agriculture and sponge city design, as well as vigorously improving the water storage function of reservoirs and canals that are more important in Jinjiang.User B suggested that sponge city refers to a city that is like a sponge and has good ''elasticity'' regarding environmental changes, adaptation and reaction to natural disasters.It absorbs, stores, infiltrates, and purifies water when it rains Water resource "circular water resources", "water resources", "renovation of water supply", "water system", etc User C posted, "Chinese water resources are in short supply, and there is a huge demand for water resources.Rainwater collection and utilisation technology can greatly alleviate the consumption of water resources such as municipal and irrigation water, and can also reduce environmental problems such as urban waterlogging and ecological balance damage".Likewise, another user said that the construction of sustainable and circular water resources is indeed significant Water environment "water accumulation point", "regional water elasticity", "water catchment areas", "water body", etc User D says we should further promote the classification of domestic waste and urban landscaping and eliminate black and smelly water in built-up areas of cities above the prefecture level, making the urban environment more liveable Water ecology "ecological water restoration", "water conservancy", "sustainable water", "water conservation", "water balance", "water permeability", etc User E said there is no water accumulation in summer, and the road surface is bonded with natural stones and colloids, with a water permeability of 70%.There are many green plants in Guixi ecological park, and the design is excellent, which will effectively reduce the heat island effect in the area.You can jog and do morning exercises here.User F said, the project adopts the concept of hydrophilic, living water and good water in Singapore's ABC water plan and combines the advanced experience of Fengxi new town to build according to the local conditions, harmonious human and ecological water restoration, comprehensive management, and implemented by local government divisions (continued) Table 3.

Detailed information about "water"
Perception of sponge city peaked at 100,390 in 2021 (Table 4).Table 4 describes good news about China's Construction Second Bureau Qilu Branch winning one provincial engineering construction method in Shandong Province.The user shared sponge city knowledge and "PDS Anti-siphon Drainage Collection System Construction Method".This kind of knowledge sharing is popular with the public on Weibo and benefits the public, sponge city managers and governments.
On the contrary, some negative blogs attracted many likes (Table 4).Sheng**'s blog, with 2,623 likes, reported that the central investigation team revealed that Zhengzhou spent ¥50bn on the "sponge city" project, but only 32% of it was used in related projects.He added that it did not seem to have any effect during heavy rain.But many experts pointed out that similar views were biased.The severe rain disaster in Henan this time was very rare.One-third of last year's rainfall fell within one day.The amount of rainfall exceeded the ability of the sponge city to deal with it, and it has nothing to do with the sponge city.The recurrence period of the waterlogging prevention and control design in Zhengzhou city matches the city scale.If it is designed according to this extreme situation, it will cause serious waste of resources.Gu**'s blog, with 4,702 likes, mentioned Beijing's rainwater in 2020.It is similar to Zhengzhou's case.A blog with 921 likes was posted in 2016.Since the second half of 2015, due to the sponge city project, rail transit construction and elevated road construction in Jinan City, roads are frequently repaired, resulting in extreme traffic congestion for a long time, and many Jinan citizens have been angry.People suggested that "Jinan should be blown up and rebuilt".Despite controversies, the Jinan Municipal Government did not remove the posts but actively responded to public comments.

Publish location analysis
Among 286 locations, this study selected the top 30 sites with higher frequencies.Thirty popular sponge cities on Weibo are as shown in Figure 7. Beijing (203), Xi'an (157) and Zhengzhou (102) ranked top 3. 17 out of 30 pilot sponge cities recorded the largest number of Weibo posts.Special funds from the central government subsidise these 30 pilot cities. Beijing is the first batch of pilot sponge city in 2016.Besides Beijing, top 30 sponge cities with largest number of Weibo posts include Wuhan (71),

Contents about water Related keywords
Examples from users Water culture "water landscape", "water recreation" User G suggested we "make water conservation a habit in the capital city".User H proposed to include water culture in education."Fine arts and environmental design graduation exhibition: relying on the original pattern for landscaping and functional arrangements, and then extracting the site's history and culture memory, integrated into the design details, it forms a coherent campus ecological network system based on water, and creates a place for teachers, students and residents to watch, rest and play" Source: Created by author; https://m.weibo.cn/Table 3.  24) are all pilot sponge cities in China.

IJCCSM
The other cities with higher frequencies are not the pilot sponge city, such as Xi'an (157) and Zhengzhou (102).These cities have once suffered from severe rain and flood disasters in recent years, including 7.20 Zhengzhou Heavy Rainstorm in 2021 and 7.24 Xi'an Heavy Rainstorm in 2016.Thus, these cities' citizens posted more microblogs about sponge cities.The city with practices and constructions of sponge cities or some cities that occurred rainwater and urban flooding may become popular and influential cities on Weibo in the context of sponge city research.People live in sponge cities publish more blogs about sponge city than people living in traditional cities.

Sentiment analysis
To explore the public's attitude towards sponge city, CX Data Science of Simply Sentiment tools analyses the 53,586 contents from Weibo.A total of 58% were positive (þve) (Figure 8), and only 14% were negative (-ve).Positive sentiment accounted for 76.8%, which was fourth times higher than negative one (18.5%, Figure 9), confirming sponge city might help city branding online.Although Fu et al. (2022) held that there is a limit to how much rainfall sponge cities can absorb, they are unlikely to be a panacea for urban flooding problems.Uncertainty in sponge city design and planning and insufficient funding are the most severe issues that can   IJCCSM lead to the failure of the sponge city concept (Nguyen et al., 2019).Besides, some people post on Weibo about sponge city with negative attitude (Section 5.2).Most public users were optimistic about the sponge city initiative.Positive sentiments included "improve", "comprehensive", "good", "high quality", "beautiful", "support", "improvement", etc. (Figures 10 and 11), while the negative sentiments consisted of "waste", "problems", "pollution", "problem" "epidemic", "disaster", etc. (Figures 10 and 12).These negative sentiments might provide useful insights for future sponge city plans making or strategies.

Results and discussion
The sponge city is closely related to climate issues, especially urban flooding and rainwater hazards.Climate change, Climate change, increased urbanization, and ineffective urban planning regulations have resulted in water-related issues in numerous countries, including flooding hazards, water pollution and water scarcity (Nguyen et al., 2019).Climate change and related issues were frequently mentioned in sponge city.This is related to people's expectations of more hazards will, emerge, cities will face more severe and complex climate change risks, impacting human health, economic development and ecosystem services (Zhai et al., 2019).Likewise, in China, climate change and sustainable urban development are extremely prominent issues (Zhai et al., 2019).Modern urban flood management includes engineering methods like infrastructure construction and public opinion mining to know more about their perception to ensure better public participation via social media and enhance preparation for flooding and response (Lu et al., 2022).
To answer the first research question, the word frequency results indicated that Weibo's users focused on "water".The co-occurrence networks reflected that "water" remained the most critical issue in sponge city construction.A specific urban water management strategy for a sponge city is a complex approach that faces many challenges (Nguyen et al., 2019).It indicated that water is an essential topic related to sponge cities in public perception.The public focuses on five aspects: water safety, resources, environment, ecology and culture.The former four factors are related to urban water circularity.The essence of sponge city construction should be classified into the category of comprehensive improvement of the five elements of urban water.We need to consider the natural water cycle and social cycle as a whole and construct a sponge city based on national conditions.
To answer the second research question, this study analysed the annually published blogs with the most likes from 2013 to 2022, except for the most popular blogs in 2021, to IJCCSM share knowledge about sponge cities.The sentiment results indicated that 76.8% were positive, meaning that sponge city might be helpful in building a positive city image and enhance city branding.Nevertheless, some blogs criticised certain sponge cities (such as Beijing, Jinan and Zhengzhou) per Table 4 and attracted many likes.For example, the user criticised the sponge city in Zhengzhou but ignored that the rainstorm disaster in 2021 was very rare, and the heavy rainfall exceeded the sponge city's capacity.
According to Thadani et al. (2020), given the significant impact of online social media on brand image, PRC has used online social media for urban project promotion like sponge city.That can also encourage public participation in sponge city design and construction and advocate for all stakeholders to work together in water resource cycle and climate change projects.Public involvement in the sponge city design and construction process can be incorporated into the government's strategic planning and city brand building.Besides, while the government might collect public opinion through social media, it is also important to note that some social media content might be biased (Finch et al., 2016).
To answer the third research question, the parts of speech showed that many blogs are related to governments' systematic planning, report, commitments, implementation, projects, etc.The content analysis results reflected that the public and sponge city managers, and governments could benefit from the sponge city's information on Weibo.It proved that the sponge city concept had been communicated to the public.In addition, people who live in sponge cities are more likely to post related blogs.As questionnaires in offline communities were done by Luo et al. (2022), residents of sponge cities are generally satisfied with the travel and living conditions and have strongly supported the local government.The online public's perceptions are affected by the living environment's differences.Many writers, who wrote about sponge cities, are those with frequent and severe rainwater and flooding.They are more likely to learn about or even support the sponger city initiative than people elsewhere.As more young people use social media like Weibo, the results may conclude that young people support the sponge cities movement.Moreover, sponge cities' relevant enterprises may pay attention to Weibo for better branding.

Conclusion 6.1 Theoretical implications
To assess sponge city's limitations and opportunities, this article critically assesses social media Weibo users' awareness and perceptions of sponge cities.It examines sponge city's popular topics, published locations and the public's sentiment about sponge cities on Weibo.The study revealed the popularity of sponge city on Weibo, contrary to experts who pointed out that sponge city lacks public participation (Wang et al., 2022) .Comparing with the traditional research methods like surveys with offline public people and community, it contains more critical reviews which can improve policies and regulations to incorporate social goals and to include the public in the sponge city-building process.

Practical implications
The study supports the public's foci and perceptions, especially the five "water" strategies and circularity (safety, resources, environment, ecology and culture) for online governments and city managers.These results will be beneficial in sponge city's decision-making.Moreover, the shift of scholarly attention from city marketing to city branding opens a new era in the representation and meaning of city branding (Thadani et al., 2020).Government can increase online social media publicity and education to cultivate people's awareness of water conservation and make water conservation everyone's action.Related departments can let the public learn about and participate in the sponge city construction.They can also Perception of sponge city encourage public on Weibo to actively respond to urban climate change issues, strengthen adaptation and mitigation measures and choose development paths to enhance the city's climate adaptation via the sponge city plan.

Limitations and future research directions
Although public opinion collection via social media could be faster than questionnaires, the sample data may mainly focus on young people and miss older people who do not use that.
Further research might focus on senior public's opinion on sponge city by using traditional research methods like delphi interviews.Besides, it may be possible to apply the same approach to study other topics like smart and low-carbon cities and ecosystem projects that lay a solid foundation for improving carbon sink capacity.
Figure 1.Method flowchart Figure 3.The top 300 keywords with high frequencies Shanghai (62), Shenzhen (58), Pingxiang (56), Chongqing (53), Suining (49), Guyuan (48), Tianjin (45), Changde (45), Nanning (40), Qingyang (39), Jinan (38), Hebi (36), Chizhou (35), Baicheng (35) and Zhuhai ( Figure 4. Weibo co-occurrence network in Sponge city Figure 6.Most mentioned verbs in sponge city Figure 8. Net sentiment Figure 11.Positive sentiment on sponge city average, and more than 60,000 deaths from 1991 to 2021.It caused an average annual direct economic loss of about 163.2 billion CNY and approximately ¥5.05tn (Ministry of Emergency Management of the PRC, 2022).China wishes to transform 80% of built-up areas to sponge cities by 2030.China's strategic plan at the national level regarding sponge city includes notices, commitments, systematic planning and implementation.Table According to the Ministry of Water Resources and the Ministry of Emergency Management of the People's Republic of China (PRC), flooding in China caused about 1,974 people die or missing annually on studied China's sponge city's ecosystem-based adaptation to address urbanisation and climate issues.Applying the Geodesign framework as an integrated

Table 2 .
Top Water is the most influential and popular keyword on Weibo.The topic of water in sponge city on Weibo can be classified into five aspects:

Table 4 .
Citizens suggested that "Jinan was blown up and rebuilt" and the Jinan Municipal Government replied] Since the second half of 2015, due to the sponge city project, rail transit construction and elevated road construction in Jinan City, roads have been frequently repaired, resulting in extreme traffic congestion for a long time that made many Jinan citizens angry On 6th Jan., the Municipal Government Public Information Network released the "Implementation Plan for the Improvement of "Clear Water and Green Banks" in the Main Urban Area of Chongqing. ..Meet the requirements of sponge city planning indicators, and the green coverage rate of the green buffer zone will reach more than 80% Shandong Provincial Provincial Engineering Construction Method.The PDS anti-siphon drainage collection system in this construction method collects infiltrated water and uses it as water for garden irrigation to save water, improve the urban ecological environment and improve urban flood control, drainage and disaster reduction. ..Sponge city follows the sixcharacter policy of "infiltration, stagnation, storage, purification, use, and drainage" . . .2022 Sheng** For example, some time ago, the central investigation team revealed that Zhengzhou spent 50 billion yuan on the "sponge city" project, but only 32% was used on related projects.During heavy rain, it did not seem to have any effect