Mapping urban dynamics in Greater Sydney – A scalable multi-decadal local climate zone classification approach

Abstract

Urbanization has significantly altered land surface properties, leading to changes in local micro-climates and impacts on regional climate. To understand these changes, long-term, precise urban land use and land cover (LULC) data are essential. The Local Climate Zone (LCZ) classification has emerged as a high-resolution urban LULC mapping scheme, which classifies urban areas and their natural surroundings into 17 classes. However, previous efforts have primarily focused on single-year LCZ mapping. To address the lack of temporal changes, this study introduces a new approach for multi-year LCZ classification using the World Urban Database and Access Portal Tools (WUDAPT) framework. We generated the first high-resolution, multi-year LCZ maps for the Greater Sydney Region from 1990 to 2020 at five-year intervals, with each map achieving over 65% classification accuracy, surpassing the accuracy threshold set by WUDAPT’s workflow for urban land cover reliability. The LCZ map reveals significant urban expansion and densification across Sydney, particularly after 2005. The total area covered by compact and open mid and highrise LCZ classes (LCZ 1–5) has increased significantly, with growth ranging from about 56% (LCZ 1) to 493% (LCZ 5). Meanwhile, open lowrise (LCZ 6) and sparsely built (LCZ 9) areas declined by 23.84% and 15.44%, respectively. This shift toward denser urban development underscores the utility of multi-year LCZ mapping to track urban dynamics over time. Transferable to any global city, this multi-decadal LCZ mapping approach improves urban land cover accuracy at high-resolution and can enhance the precision of urban simulations. These LCZ maps support application in urban planning, climate adaptation, environmental assessments, and urban meteorological modelling, providing researchers, policymakers, and urban planners with valuable tools to address climate resilience and urban growth management effectively. Future work can integrate these LCZ datasets with climate and hydrological models to assess the long-term impacts of urban expansion on extreme weather, heatwaves, and flood risk, and apply this classification approach to other cities for comparative urban studies.