Visualising Sustainable Development Goals progress of China’s coastal cities using circular-kaleidoscope charts

Cities are the frontiers of the Sustainable Development Goals (SDGs) adopted in the United Nations 2030 Agenda. Although quantitative methods have been applied to assess cities’ sustainability progress, knowledge gaps exist in the differences between inland and coastal cities’ performance and their internal variations against common standards. Using the Voronoi-based kaleidoscope diagram embedded in two circular plots, the article visualises the overall sustainability progress of China’s inland and coastal cities in economy, society, biosphere and partnership. By measuring overall progress with circular length and individual scores with kaleidoscope area size, triple inland-coastal gaps and trifold intracoastal inequalities were highlighted, as well as city types characterised by economy-society balance and land–sea relation. References for implementing sustainable development transformations for coastal cities were derived, along with the circular-kaleidoscope diagram’s potential for checking the pulse of cities’ performances in further uses and finishing the circle.