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Rapid urbanization of the Belt and Road Initiative (BRI) region has undoubtedly led to changes in the scale, form, and pattern of cities to accommodate the expansion of industry, housing, and commerce and to produce sustained impacts on environmental sustainability. However, limited studies have yet to systematically investigate the urban expansion in this area. Based on a systematic research path of "pattern-mode-coordination-sustainability", this study quantified the urban expansion dynamics of BRI countries and 80 representative cities from 2000 to 2018 using multi-source remote sensing data and the Global Atlas of Urban Expansion. The results show that in terms of dynamic rules, the share of urban lands grew from 0.32 % in 2000 to 0.66 % in 2018 (an increase of 250,600 km2) and is estimated to increase to 1.68 % in 2018–2030. Countries in developing regions (i.e., West Asia, North Africa, and Southeast Asia) are predicted to become the new high-value centers of urban expansion intensity (UEI). The UEI of BRI cities showed a significant developing region orientation and "high in the east and low in the west" distribution pattern but would gradually shift towards a spatially homogeneous and discrete distribution. BRI cities can be divided into four expansion modes (center-periphery, double-winged strip, dual-core cluster, and single-winged mutation expansion), each with a different evolutionary dynamic mechanism. Regarding coordination, there is a great demand for land expansion by population and economic growth in BRI cities. This dependence increased as the city's UEI index rose; when the UEI exceeded 3 %, the dependence became more pronounced. The investigations also showed that the adverse ecological effects of urban land expansion are gradually increasing at the urban scale. Furthermore, the ecological impacts of population growth are usually the strongest for BRI's countries and cities, and the intensity showed a synergistic growth trend with the UEI index. This study provides new insights into the dynamic features of BRI's urban expansion from national to urban scales and historical to future periods, while also contributing new perspectives from the BRI to optimal global land management and sustainable urban development. • Provides new insights into BRI' s urban expansion from national to urban scales and from historical to future periods based on the research path of "pattern-mode-coordination-sustainability". • Dependence of population and economic growth on urban land use increased with city's UEI index. • Ecological impacts of population growth are the strongest for BRI region, and showed a synergistic growth trend with the UEI index. [ABSTRACT FROM AUTHOR]

Africa has been undergoing a rapid urbanization process, which is critical to the achievement of the 11th Sustainable Development Goal (SDG11). Using population density data from LandScan, we proposed a population density-based thresholding method to generate urban land and urban population data in Africa from 2001 to 2019, which were further applied to detect the spatiotemporal characteristics of Africa's urbanization. The results showed that urban land and urban population have both grown rapidly in Africa, which increased by about 5.92% and 4.91%, respectively. The top three countries with the most intense urbanization process in Africa are Nigeria, the Democratic Republic of the Congo, and Ethiopia. The coupling relationship index of urban land expansion and population growth was 0.76 in Africa during 2001–2019. Meanwhile, the total proportion of uncoordinated development types at the provincial level was getting higher, which indicated an uncoordinated relationship between urban land expansion and population growth in Africa. Cropland, grassland, rural land, and forests were the most land-use types occupied by urban expansion. The proportion of cropland, grassland, and forests occupied was getting higher and higher from 2001 to 2019. The extensive urban land use may have an impact on the environmental and economic benefits brought by urbanization, which needs further research. [ABSTRACT FROM AUTHOR]