Urban low-altitude airspace resources: Integrating risk and accessibility through fine-grained analysis

With the rapid pace of urbanization, low-altitude airspace is increasingly recognized as a critical resource for smart and emerging urban systems, supporting applications such as UAV-based logistics and urban air mobility. However, conventional airspace planning methods have not adequately captured the complexity and dynamic variability of urban morphology. In response, this study proposes an innovative, data-driven framework for the fine delineation of low-altitude airspace. By integrating multiple high-precision geospatial datasets and employing the H3 hexagonal grid system as the spatial discretization framework, the framework quantitatively assesses airspace risk and accessibility. Using a case study of airspace below 120 m in Shenzhen, the analysis reveals distinct variations in airspace attributes across different flight altitudes and time periods. Results indicate that risk exhibits a pronounced bimodal distribution with significant differences among functional zones, while, after accounting for uncertainties in UAV performance and flight conditions, the feasible airspace (measured as true altitude) stabilizes above 60 m with a deceleration in growth. Furthermore, the integration of built-up area and local climate zones (LCZ) analyses effectively elucidates differences in risk and accessibility, providing unprecedented data granularity and a computational platform for characterizing the spatiotemporal evolution and attributes of low-altitude airspace. This study offers theoretical support for the sustainable development of the low-altitude economy and introduces new perspectives for the scientific planning and precise management of low-altitude airspace. • Comprehensive analysis of low-altitude airspace risk and accessibility across the urban area. • Spatiotemporal characterization of population exposure risk from UAV operations. • Identification of significant altitude-dependent variations in airspace accessibility. • Exploration of the feasibility of fine-scale airspace management using the LCZ framework. • Recommendations for sustainable urban low-altitude economy development and precise airspace management.