Comprehensive management of excavated soil and rock: A material flow analysis in Shenzhen, China

China has been experiencing rapid urbanization, resulting in intensive construction activities. Accordingly, massive excavated soil and rock (ESR) have been generated and disposed of yearly, which is detrimental to the natural environment and induces geological disasters. However, current research is insufficient to characterize the ESR compared to other construction and demolition waste. Therefore, this study aims to use Shenzhen, a fast-growing megacity in China, as an example to quantify the generation and flows of ESR. Data was collected from official documents and field investigations between 2015 and 2021. The results indicate that more than 80 million m3 of ESR was generated in Shenzhen annually, primarily from building and rail transit construction projects. Approximately 72% of ESR was transported and traded with other neighboring cities. Meanwhile, recycling activities have digested a minor amount of ESR, with a low weight fraction below 10%. The findings suggest the significance of ESR minimization and recycling in reducing environmental risks. Regional collaboration is also crucial between the cities in the Pearl River Delta to optimize cross-jurisdictional ESR trading. Overall, this research offers references to enhance environmentally sound management of ESR in Shenzhen, which may also be applied to other Chinese cities.