Work

A Multiscale Thermal Environment Network Framework for Urban Agglomerations: Changes from 2000 to 2020 and Planning Insights from the Hangzhou Bay Region

Year: 2026

Type: article

Abstract: Against the backdrop of climate change and rapid urbanization, the urban thermal environment (UTE) in urban agglomerations continues to deteriorate, posing a growing challenge to regional sustainability. Network-based approaches have increasingly been applied to UTE studies, but most studies have focused on a single spatial scale, with limited attention to thermal connectivity at different scales. Therefore, this study used land surface temperature (LST) data from 2000, 2010, and 2020 together with the Patch-generating Land Use Simulation (PLUS) model and circuit theory to construct a multiscale UTE network framework for the Hangzhou Bay urban agglomeration. A cooling network was constructed at the urban-agglomeration scale and a heat network within the national-level urbanized zone, and temporal changes in each scale-specific network were examined across the three study periods. The results showed that: (1) Low-temperature areas remained concentrated in the southwestern mountains and major water bodies but continued to shrink, whereas high-temperature areas expanded and gradually coalesced across areas surrounding Hangzhou Bay, with more pronounced clustering within the national-level urbanized zone. The total area of cold sources decreased from 3249.76 to 2411.50 km2, whereas that of heat sources increased from 1061.32 to 2896.28 km2. (2) At the urban-agglomeration scale, the mean corridor length of the cooling network increased from 12.23 to 17.41 km, while the α, β, and γ indices declined continuously; within the national-level urbanized zone, the mean corridor length of the heat network decreased from 17.85 to 10.30 km, with all three indices reaching their highest values in 2020. (3) Cooling-network barriers spread from cold-source clusters into transitional areas linking cold sources with urbanized areas, whereas heat-network pinch points shifted from established heat-source clusters to emerging ones. This study provides a multiscale network perspective on thermal connectivity in urban agglomerations and offers spatial evidence for cross-regional thermal-environment management and climate-adaptation planning.

Source: Land

DOI: 10.3390/land15101926