Green and low-carbon construction strategies for river regulation projects based on LCA carbon emission accounting and multi-scenario analysis： a case study of Jurong River in Nanjing

The green and low-carbon construction of river regulation projects is an important part of the green transformation of water conservancy projects under the goals of "carbon peaking and carbon neutrality". Aiming at the common problems existing in the green and low-carbon construction of traditional river regulation projects， such as excessive qualitative descriptions of strategies， insufficient life cycle assessment （LCA）， excessive process analysis， and inadequate multi-scenario guidance， this paper took the demonstration section of the Jurong River Regulation Project in Nanjing as a case study. Based on identifying the carbon emission characteristics of river regulation projects via LCA， an environment-economic dual-objective model was adopted to conduct scenario analysis for the selection of green and low-carbon construction technologies under different objectives， and corresponding combined strategies of green and low-carbon technical measures were proposed. The results showed that the carbon emission intensity during the construction period of the Jurong River demonstration section（length 8.46 km） was 2705 t CO2eq/km， among which the raw material production stage accounted for 92.49%， followed by the engineering construction stage （5.75%）， engineering transportation （1.06%）， and engineering preparation （0.70%）. Multi-scenario analysis indicated that the application of measures including low-carbon new energy transportation， fly ash， and recycled concrete could reduce carbon emissions by 4486 t CO2eq and achieve an optimal economic benefit of RMB 1.0814 million. The combination of fly ash， recycled aggregate concrete， and carbon capture and reduction cement （with a replacement rate of 90.32%） could reduce emissions by 7551 t CO2eq， realizing a balance between economic and environmental performance. Implementing all carbon reduction measures could achieve a carbon reduction of 9596 t CO2eq but would require an investment of RMB 1.1337 million. The scenarios of maximum economic benefit and economic-ecological balance present better engineering applicability and can provide a decision-making basis for the green and low-carbon construction of river regulation projects.