Review of 'Tacit knowledge in water management: a case study of Sponge City'

The study is exploratory research that explores the characteristics of tacit knowledge empirically in China’s Sponge City pilot project by identifying the extent of using three types of tacit knowledge - relational, somatic and collective tacit knowledge, falling along a spectrum of weak to strong. The research analysed qualitative data obtained from semi-structured interviews with different practitioners in the Sponge City project, applying both inductive and deductive coding processes. As the first step in examining interactive communications among a diverse range of water specialists, the results provide groundwork in favour of mobilisation of tacit knowledge in the Sponge City project, which has been gradually upgraded as a national action in China lately, at various locations of Chinese cities. The insights from practitioners also help identify future research needs for sustainable water governance in China.

The manuscript is well-written, timely and relates to an increasing global interest in Nature-based Solutions and a burgeoning concept of China’s Sponge City. I highly appreciate the study's originality and the sociological analysis of knowledge transmission in the Sponge City program. Nevertheless, I believe some revision is still needed; the following concerns should be considered critically to make this review more logical, profound, and straightforward.

Major points

The introduction (1-3) lacks a clear structure. Elements of tacit knowledge, sustainable urban water management, and the Sponge City concept are loosely connected. The reason why the Sponge City project is considered a sustainable urban management practice and the knowledge context of Sponge City is missing. The term “knowledge brokers” described in the results should also be introduced in the introduction.

The methods (4) are not sufficiently clear. Which cases of the Sponge City pilot project were selected? The geographical scope of the manuscript could also be more explicit as Sponge City has been implemented in many Chinese cities; each of them faces different water challenges and has different water governance dynamics. How were interviewees identified? How many were the interviewees in each stakeholder group (U, G, C, P; and no actors from public/civil society?)? How were the three rounds of the coding process carried out? Besides, “the actors interviewed can be divided into five groups based on their professions”, but there are only four (U, G, C, P).

For the results (5), the features and characteristics defined and discussed with the analytical framework were not well illustrated. There is a lack of sample quotes of knowledge exchange between actors regarding site-specific actions in pilot Sponge City (again, which city is chosen?), as Sponge City is an umbrella project that involves a series of engineering and/or non-engineering measures, e.g., river/lake ecological restoration, upgrade of sewage system, rain garden, green roof/wall, etc. Different stakeholders are involved to a different extent in different initiatives (and are all these initiatives top-down?). I failed to find data analysis compelling about how different tacit knowledge is distinguished, identified and categorised in a sweeping statement of “Sponge City”. I suggest breaking down an overarching Sponge City program and adding a summary table composed of each tacit knowledge type (relational, somatic, collective tacit knowledge), keywords (direct quotes from interviews) and features extracted, the corresponding percentage of interviewees’ expression, etc.,

The role of urban planners was described both in 5.2 and 5.4 as vitally important to guide the Sponge City project. I found their position a bit confusing. In China, some urban planning institutes are “public service units” (shiye danwei) providing public services alongside core government, and some are private companies bidding on public construction contracts. Their relationship and interaction with the local government thereby vary, as well as their abilities to play an “integrating role”. With the new national policy of River Chief System (Hezhang zhi) launched in 2016, the newly appointed River Chiefs (He-zhang) tend to take the leading, coordinating and facilitating role of all projects related to surface water bodies under their jurisdiction (but the implementation of River Chief System also depends on locations).

5.3 analysed a collective tacit knowledge rooted in Chinese culture and China’s modern political system. It will be good to add the “top-down information asymmetry”, in which higher authorities in China often strategically issue ambivalent orders or give ambiguous information to their subordinates, which may induce national plans poorly enforced at the local level, but also gives the flexibility of implementation and encourage policy innovation. In addition, it is also worth describing the evolution of Chinese water culture that governs the relationships between water professionals – from overall harmony between humans and nature in ancient times to intensive water-engineering projects to explore water resources for human use after the founding of the People’s Republic of China in 1949, and to (finally) a shifting focus on “ecological civilisation” from 2012.

At the end (6), a more comprehensive conclusion section would be desirable. As the list of pilot Sponge City continues to extend in China, there is a need for guidance on improving the complex governance structure of the Sponge City program. Though remaining a preliminary set and context-specific, the research findings in the manuscript constitute a good base in this regard. Some practical suggestions to resolve the present communication barriers would be helpful. I have no doubt it will be of interest to many researchers and policymakers.