Spatiotemporal evolution and influencing factors of carbon stock in the water receiving areas from the perspective of carbon neutrality

Water resources of water transfer projects are not only used to solve the water scarcity problem in the water-receiving area but also to change the regional carbon absorption capacity. Using the water-receiving area of the Jiangsu-Shandong section of the East Route of the South-to-North Water Diversion Project (ER-SNWDP) of China as a case study, this study explored the dynamic variation in carbon stocks in response to water diversion project in the context of carbon neutrality. The results showed that (1) After the ER-SNWDP came into operation, there was a trend of growth in water area. Based on multi-scenario simulation, under the ER-SNWDP scenario, built-up land expansion would be curbed, forest and grassland reductions would be alleviated, and water areas would increase significantly compared to the natural variation scenario. (2) Due to the implementation of the project, the research area had better carbon sequestration capacity. Under the natural variation scenario from 2015 to 2025, the carbon stock would decrease by 1228.35 × 10⁴ t. However, under the ER-SNWDP scenario, there would be an increase of 262.84 × 10⁴ t. In addition, the water resource allocation of ER-SNWDP may affect the spatial distribution of carbon stocks. In the northeast region, particularly in the Binzhou and Dongying areas with large water transfer volumes, the increase in carbon stocks was significant, and the center of gravity of increase also tended to tilt these areas. (3) Land use had the highest explanatory power and driving force for spatial variation in carbon stocks. According to the results of the interaction factor analysis, the strongest interaction factor after 2005 was "land use ∩ nighttime lights", indicating that the interaction between socio-economic factors and land use factors gradually amplified the impact on the spatial variation of carbon stocks. This study provides a scientific basis for future land use planning, promotes the rational and optimal allocation of water and carbon resources, and provides a prospective reference for water resources to cope with climate change and achieve carbon neutrality.