Urban-rural fringe identification and spatial form transformation during rapid urbanization: A case study in Wuhan, China

Urbanization and industrialization are widespread in China, but spatial form changes during urban sprawl are not explored in depth. This paper investigated the variation of the local climate zones (LCZs) within urban-rural fringe (URF) from 2010 to 2020 in Wuhan. Based on normalized multi-source data (population density, nighttime light and land use data), the spatiotemporal distribution of the URF was obtained through K-means. LCZ maps for different years were produced by SAGA-GIS. The silhouette coefficient (SC), the sum of the squared errors (SSE), and the consistency ratio (CR) were selected to evaluate the accuracy of clustering and identification. We found that: 1) the identified UC and NUC areas were added up to be consistent with the published developed area and the CR values were all above 70%. 2) the middle region within the URFs has a high average annual growth area (AGA) and annual average area growth rate (AGR), while the urban-rural gradient within URFs near rural areas has become steeper. 3) LCZ 4, LCZ 8 and LCZ 10 were usually distributed in the NUC (nearurban core), LCZ 6 has always been in the NRA, and LCZ D always had the highest proportions in all URFs. 4) LCZ 1, 4, 8 and E continuously increased within all URFs, and with the maximum AGRs of 0.16%, 1.53%, 1.01% and 0.18%, respectively. This study presents the development characteristics of high-rise residential areas and lowrise industries in the URFs in a Chinese mainland city.