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Given the fact that the high frequency of extreme weather events globally, in particular typhoons, has more of an influence on flood forecasting, there is a great need to further understand the impact of typhoon events on design storms. The main objectives of this paper are to examine the magnitude, occurrence, and mechanism of typhoon events in southeast coastal China and their contribution to the design storm study. We take Shanghai, which is a typical metropolitan region in the Yangtze River Delta, China, as an example. The impact of typhoons on the rainfall frequency analysis is quantitatively evaluated using stochastic storm transposition (SST)-based intensity–duration–frequency (IDF) estimates with various temporal and spatial structures under different return periods. The results show that there is significant variability in the storm magnitude within the transposition domain across different durations, highlighting the spatiotemporal heterogeneity over the coastal area. Moreover, the probability of random storm transposition exhibits an uneven distribution. The frequency of typhoon rainfall events within the transposition domain is notably high, and there is considerable variability in the structure of rainfall. Typhoon rainfall amplifies the intensity of design storms, and its contribution increases with return periods. The variability in design storms increases accordingly. Based on the advantages of SST, which retains the spatiotemporal structure of the rainfall in the generated scenarios, the overall framework provides an effective way to examine the impact of diverse characteristics of typhoon rainfall on frequency analysis and facilitate a deeper exploration of the direct impact of various types of extreme storms on the intensity, spatial, and temporal distributions of design storms amidst evolving environmental conditions over this metropolitan region. [ABSTRACT FROM AUTHOR]

The three metropolitan regions, including Jing-Jin-Ji (JJJ), Yangtze River Delta (YRD) and Pearl River Delta (PRD), are the most developed regions of China. This study focuses on these three metropolitan regions and tries to estimate and analyze the structure and influencing factors of CO2 emissions from transport sector, including passenger and freight transport, simultaneously covering road, rail, and water transport. The results suggest that in the period of 2000–2013, the CO2 emissions from transport sector increased from 27.8 to 198.8 Mt in JJJ, from 29.7 to 163.5 Mt in YRD, and from 13.1 to 74.0 Mt in PRD. Comparatively speaking, JJJ had the highest CO2 emission intensity of freight and urban passenger transport as well as highest transport CO2 emissions per capita and per unit GDP, while PRD had the highest transport CO2 emissions per hectare. The main challenge of reducing CO2 emissions from transport sector in these regions stemmed from freight transport and road transport. Based on decomposition analysis, economic welfare was the most important driving force of the CO2 emissions growth in all three regions, followed by transport type mix, transport dependence and modal energy intensities. In the future, low-carbon transport strategies about controlling the growth of transport demand, adjusting the transport modal structure and improving the modal energy efficiency and fuel emission efficiency are needed in all three regions, and each region should have slightly different focus. The JJJ region needs to emphasize adjusting transport modal structure, the YRD region needs to emphasize improving modal energy efficiency, and the PRD region needs to focus more on controlling the growth of transport dependence. [ABSTRACT FROM AUTHOR]

Graphical abstract a. The evaluation and analysis framework of ecosystem health assessment; b. clustering analysis based on the two-dimensional graph theory; c. changes of ecosystem health during 2001–2007, 2007–2013. Highlights • Deterioration of regional ecosystem health diffused from coastal areas to inland. • The regional ecosystem health changes were largely due to the decline in ecosystem vigor. • The landscape fragmentation leads to a drop in local ecosystem organization. • Visualization of ecosystem health changes revealed the impact of central cities/counties. • The evaluation results at different scales offer enlightenment for global and local planning. Abstract The ecosystem health of coastal metropolitan regions is changing, which will exert a negative impact on human survival and development in the future. In this case, it is a novel and effective method to evaluate the regional ecosystem health based on land use/land cover change (LUCC) and landscape ecology theories. This paper constructed an integrated ecosystem health assessment framework (top-down), including objective layer, factor layer and index layer. Comprehensive and detailed analytical methodologies (bottom-up) were employed to explore the process of ecosystem health change in Shanghai and Hangzhou Bay (SHB) at multiple scales. The results showed that, in the two periods of 2001–2007 and 2007–2013, the regional ecosystem health status continued to degrade at city scale, and this decline spread to the surrounding areas from the central cities (Shanghai and Jiaxing). Similar diffusion phenomenon was also observed at county scale (centered on Downtown Shanghai). Notably, the vigor factor was found to make the greatest contribution to the changes of ecosystem health. To conclude, integrated assessment framework and comprehensive/detailed analysis combined with LUCC and landscape patterns are meaningful exploration for ecosystem health assessment, and clustering analysis provides a foundation for government to formulate regional planning and management policies pertinently. [ABSTRACT FROM AUTHOR]

Although mega-city regions have attracted wide attention in China, recent 'metropolitanization' at the multi-city scale is poorly understood. To tackle the void, this paper examines the emergent 'metropolitan plans' (dushiquan guihua) since 2019 and identifies a paradigm shift in metropolitanization from 'territorial urbanization' to 'multi-city regionalism' in China. We find that 1) as a fuzzy and dynamic concept, the metropolitan region has been mainly employed as a policy object for state rationalities and has been upscaled from a city region scale to a multi-city scale; 2) regarding planning practices, the new metropolitan plans function as an overall collaborative framework to support priority tasks for city regionalism in a shorter term rather than formulating long-term spatial strategies; 3) as space of governance, the recent state-orchestrated metropolitan region reflects the newest round of state rescaling process to cope with domestic uneven development and urban issues through 'urban unification', and its materialization heavily relies on concrete cross-boundary projects delivery and coordination through soft governance. These findings not only provide conceptual clarity and relational understandings of the metropolitanization process but also exemplify the distinctiveness of the Chinese metropolitanization approach in terms of scalar logic, planning style, and associated governance mechanisms. This paper furthers the understanding of the divergence and diversity of metropolitan planning and governance practices in different political-economic circumstances. [ABSTRACT FROM AUTHOR]

Abstract Rapid growth of metropolitan regions has become a key issue in relation to urban governance and planning in developing countries. The past decades have witnessed a dramatic spatial restructuring in metropolitan regions in China. Although many studies have been done, conclusions are yet to achieve consensus. Several main arguments still need to be discussed further: how to identify this spatial restructuring process; what is general trend of spatial restructuring; and how the spatial restructuring are affected by a variety of institutional and economic factors. This study aims to address these arguments by scrutinizing the Yangtze River Delta (YRD) of China as a case. We use a new data set, namely, nighttime light data derived from the Operational Linescan System of Defense Meteorological Satellite Program, to explore the spatial restructuring of YRD from 1992 to 2012. Results found that urban growth in YRD has been dominated by a “dispersed” pattern before the 2000s due to local industrialization and political decentralization. However, after the 2000s, a new “clustered” trend evolved in YRD, and inequalities in regional development tend to increase. A few politically or economically (or both) advantaged cities became new growth centres, while other cities grew slowly. These advantaged cities mainly were mega cities and province capital cities. A growth of importance of domestic consumer market gave more economic opportunities to these advantaged cities which had a large population size and a better political capability to adapt new economic situation. In particular, they were enabled to have more powers to make locally privileged policies to attract investments and population in the current process of deeply market-oriented forms in China. Highlights • YRD has experienced an evident spatial restructuring. • A new “clustered” trend evolved and dominated YRD region between 2002 and 2012. • Regional inequalities in development in YRD tend to increase. • The development of YRD exhibited an endogenous process stimulated by political decentralization and marketization. • Globalization plays a crucial role in shaping spatial restructuring in China's mega-city regions. [ABSTRACT FROM AUTHOR]