Effect of urban morphology on local-scale urban heat island intensity under varying urbanisation: A case study of Wuhan

• Varying development speeds clarify Local-scale Urban Heat Island Intensity (LUHII). • Contrasting LCZ and landscape impacts on LUHII in three development-speed blocks. • Rapidly expanding blocks show the fastest LUHII growth but not peak intensity. • LCZ2→LCZ5 and LCZ3→LCZ6 transitions effectively reduce LUHII in stable blocks. • Increased Mean Shape Index intensified LUHII in moderately growing blocks. Urban spatial morphology critically impacts thermal environment distribution, essential for urban planning. However, research on the influence of dynamic changes in urban spatial morphology factors on Local-scale Urban Heat Island Intensity (LUHII) under varying degrees of urbanization remains insufficient. This study investigates the spatiotemporal characteristics of LUHII in Wuhan from 2010 to 2020, focusing on three types of blocks with different development speeds. It examines the impact of dynamic changes in Local Climate Zones (LCZs) on LUHII at the Block scale and explores the relationship between landscape pattern indices—namely, Shannon's Diversity Index (SHDI), Mean Shape Index (MSI), Patch Density (PD), and Contagion Index (CONTAG)—and LUHII dynamics using the Geographically and Temporally Weighted Regression (GTWR) model. The findings reveal that rapidly expanding Blocks experienced a sharp decline in natural LCZ types (LCZB-D) from 2016 to 2020, with reductions 12.5 times and 3.13 times greater than those in stable and moderately growing Blocks, respectively. LUHII exhibited significant spatial variations, with rapidly expanding Blocks showing the highest growth rate; however, by 2020, the mean LUHII in moderately growing Blocks surpassed that of stable Blocks by 13 %. LCZ2-to-LCZ5 and LCZ3-to-LCZ6 transitions in stable Blocks led to notable cooling effects, with a relative decrease of 10.25 % and 17.49 %, respectively, while other Blocks showed significant cooling only during LCZ6-to-LCZ9 transitions. From 2016 to 2020, most LCZ conversions resulted in LUHII increases across all Blocks. Among landscape pattern indices, contributions to LUHII followed the order SHDI > MSI > PD > CONTAG. SHDI was strongly positively correlated with LUHII, while PD and CONTAG exhibited mostly negative correlations. MSI showed a positive correlation with LUHII solely in moderately growing Blocks (β=2.779), implying that increasing shape complexity in these Blocks may hinder heat island mitigation. Urban planning should prioritize enhancing landscape fragmentation and connectivity.