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

First of all, we would like to thank both reviewers for their careful reviews and insightful comments and suggestions. We have made changes accordingly, and they are highlighted in yellow.

The following are the major areas of change in response to both reviewers:

1. Both reviewers suggested that the meaning and value of tacit knowledge as well as how the knowledge barriers are determined to be tacit are not clear. I have reorganised the section on tacit knowledge, and made it clearer that the knowledge that is explicable but not made explicit, for example, due to the barrier of the “inability to adequately explain”, is still a form of tacit knowledge. A table is added to give a definition and an example for each type and subtype of tacit knowledge. To draw a more direct link between the tacit knowledge and the Sponge City program, I added more direct quotes from the interviews to demonstrate each type of tacit knowledge in the discussion.
2. Both reviewers also commented on the ambiguities regarding the role of urban planners. I agree with both reviewers that although the role of urban planning (planners) is important to projects such as the Sponge City projects, it is not very relevant to the discussion of tacit knowledge, which is the focus of this paper. Therefore, I decided to remove the discussion on urban planning (planners) entirely to keep the paper more streamlined.
3. The conclusions are updated to better reflect the contributions of the paper and introduce the next steps following this paper.

Other specific responses to reviews by Michael McClain:

1. Page 1: We think that stakeholder engagement is a key component that contributes to the sustainability of urban water management, and since this paper is focussing on the difficulties of knowledge communication between actors/stakeholders from different disciplines, we decided to keep the definition of SUWM as it is.
2. Page 10: As the reviewer pointed out, the goal is not to change the culture, but to recognise the differences and the challenges that originated from there, so the sentence highlighted was modified.
3. Page 11: the repeated sentence was deleted.

Other specific responses to reviews by Yixin Cao:

1. Introduction: a paragraph is added to draw a clearer link between Sponge City and tacit knowledge. We think that we have provided a linkage between SUWM and Sponge City, but another sentence is added to aid the clarification.
2. Methods: More details on the case selection and the data collection processes are added. The error in the number of actor groups was fixed.
3. Results: in addition to the changes to the direct quotes and the discussion on urban planning, the comment on the top-down information asymmetry is incorporated into the results.

Sustainable, resilient urban water management is fundamental to good environmental and public health. As an interdisciplinary task, it faces enormous challenges from project complexity, network dynamics, and the tacit nature of knowledge being communicated between actors involved in design, decisions and delivery. Among others, some critical and persistent challenges to the implementation of sustainable urban water management include the lack of knowledge and expertise, lack of effective communication and collaboration, and lack of shared understanding and context. Using the Chinese Sponge City programme as a case study, this paper draws on the perspectives of Polanyi and Collins to investigate the extent to which knowledge can be used and exchanged between actors. Using Collins’ conceptualisation of the terrain of tacit knowledge, the study identifies the use of relational, somatic, and collective tacit knowledge in the Sponge City pilot project. Structured interviews with 38 people working on a Sponge City pilot project provided data that was rigorously analysed using qualitative thematic analysis. The paper is original in using theories of tacit knowledge to explain barriers and pathways for information and messages being communicated between actors in urban water management. The methods and results provide the groundwork for analysing the access and mobilisation of tacit knowledge in the Sponge City pilot project, with relevance for other complex, interdisciplinary environmental projects and programmes.