Temporal Evolution and Spatial Differentiation of Urban Solid Waste Policies in Chinese Cities: An LDA-Based Systems Analysis from a Life-Cycle Governance Perspective

Urban solid waste governance has become a key component of sustainable urban development. However, integrated analyses that combine thematic evolution and spatial heterogeneity remain scarce. This study applies an LDA-based systems analysis of USWG policies through a life-cycle governance perspective to examine the evolution of solid waste policies using a corpus of 13,161 policy documents from 35 major Chinese cities covering the period 2000–2025. The analysis compares thematic trends across three predefined policy phases grounded in major national policy milestones: Exploration period (2000–2010), Stabilization period (2011–2019), Transformation period (2020–2025). Six governance themes are identified relating to regulatory enforcement, procedural supervision, construction-site management, waste resource utilization, green innovation, and long-term institutional mechanisms. Based on these themes, the study examines changes in relative thematic shares over time and compares city-level theme intensity across urban tiers. The results show a gradual reconfiguration of policy attention, with pollution control and construction-site management remaining important while resource circulation, green innovation, and institutional coordination become more prominent. Spatially, Tier-1 cities exhibit relatively stronger attention to innovation and institutional coordination, Tier-2 cities show a more balanced profile across resource recovery and operational management, and Tier-3 cities display comparatively closer attention to enforcement and pollution control. By synthesizing temporal patterns, thematic structures, and urban-level differentiation, this study provides a systems-oriented account of policy attention in China’s urban solid waste governance. The findings offer a descriptive basis for understanding differentiated governance priorities across cities with different development conditions.