Integrating carbon and water footprint into nature-based solution (NBS) for urban planning in a highly built-up area in Guangzhou, China.

Stormwater management problems have been deteriorated with the high frequency and intensity of precipitation owing to rapid urbanization and climate variability, especially in urban highly built-up area. Nature-based solutions (NBS) have emerged as a powerful measure for rising these challenges due to their ability to mitigate urban waterlogging and increase carbon sequestration. Identifying optimal locations for NBS implementation remains a critical research focus. This study integrates carbon and water footprint accounting into NBS-based planning for sustainable urban development in central Guangzhou, China, to enhance urban flooding mitigation and carbon sequestration. Through carbon-water footprint analysis and weighting, we prioritized NBS planning. To achieve the objectives of increasing sequestered carbon and reducing urban runoff, three types of NBS-green roofs, permeable pavements, and bioretention systems-were optimized for a high-priority town street. The results showed that the implementation of green roof and permeable pavement reduced the surface runoff by 3.58 %, while the biological retention system reduced the runoff gray water by 27 %. Moreover, the application of green roof and biological retention increased the carbon sequestration by 2.57 million kg CO2-eq (life cycle). The findings of this study provide comprehensive insights into optimization of NBS planning based on carbon-water footprint accounting, facilitating to enhance mitigation of urban flooding vulnerability and carbon sequestration.