A three-dimensional future land use simulation (FLUS-3D) model for simulating the 3D urban dynamics under the shared socio-economic pathways

Existing research on urban dynamic simulations has primarily focused on horizontal aspects, whereas vertical changes have remained relatively unexplored. Although a few preliminary studies have attempted to simulate three-dimensional (3D) urban dynamics, these have generally amounted to rudimentary amalgamations of horizontal urban expansion simulation and vertical height estimation. In this study, we enhanced our original Future Land Use Simulation (FLUS) model into a 3D version (FLUS-3D) to simulate the continuous 3D dynamics of real-world urban development. A distinctive characteristic of the proposed model is its ability to concurrently update 3D information of the developed land grids during the simulation process. The FLUS-3D model was assessed via simulations across three metropolitan regions in China: the Beijing–Tianjin–Hebei, Yangtze River Delta, and Pearl River Delta regions. Satisfactory simulation performances were found across all regions, with Figure of Merit values ranging 0.21–0.35 for horizontal expansion, overall accuracy values of 83 % for the refinement of urban functional types, and root mean squared error values of 5–7 m for built-up height simulations. Comparative experiments further demonstrated a significant outperformance of the FLUS-3D model compared to that of existing models. Subsequently, the proposed model was applied to simulate the future evolution of 3D urban dynamics until 2030 under the Shared Socioeconomic Pathways (SSPs). The simulation results effectively illustrated the influence of each SSPs on 3D urban development. Given that 3D urban structures are fundamental parameters in urban climate modeling, the proposed model can potentially be used in urban-related studies climate change mitigation to achieve future urban sustainability.