Multi-scenario and multi-temporal analysis of carbon storage evolution in waterfront spaces: an integrated assessment and zoning strategy for carbon management in the middle Yangtze region

Carbon storage, a key indicator of terrestrial sequestration, reflects land use impacts on ecological security and is fundamental to regional carbon management and climate change mitigation. To support basin-scale carbon management strategies, this study examines the middle Yangtze River urban agglomeration. We coupled PLUS and InVEST models to analyze historical (2000–2020) and simulate 2030 land use and carbon storage under three scenarios: Natural Development (NS), Ecological Protection (ES), and Urban Development (DS). Using a 1 km shoreline buffer grid and Getis-Ord Gi*, we identified carbon storage hotspot/coldspot changes. Multi-temporal raster analysis first revealed three key waterfront functional units: Stable Core, Continuously Degrading, and Policy Response Areas. Results showed: (1) During 2000–2020, built-up land expanded 61.79%, while cropland and forestland decreased 4.28% and 0.65%, causing ~17.27 Tg net carbon loss. Multi-scenario simulations indicated ES, by curbing built-up expansion and increasing forest/water cover, could sequester ~3.85 Tg more carbon than NS, whereas DS would exacerbate loss. (2) The three zones comprised: Stable Core Areas (27.50% of waterfront space) in western mountains and around Dongting Lake, as carbon-sink bases; Continuously Degrading Areas (0.28%) at urban fringes, indicating persistent sink loss; and Policy Response Areas (0.26%) near Zhelin Reservoir (Jiujiang) and along the Yichang–Jingzhou river section, offering the highest marginal benefits for ecological interventions. (3) Three key lever zones were identified—stable core areas (27.50% of waterfront space), continuously degrading areas (0.28%), and policy response areas (0.26%) and using a dual-indicator assessment framework, differentiated strategies for urban waterfront space management are proposed. This study provides a basis for basin ecological protection through “zoning, targeted measures, and coordinated governance”.