Mega-city Regions Research Articles

Multi-view clustering analysis of mega-city regions based on intercity flow networks

With the booming of Big Data and the Internet of Things, various urban networks have been built based on intercity flow data, and how to combine them to learn a more comprehensive understanding of mega-city regions is becoming more and more indispensable. In this paper, we designed a graph-based multi-view clustering method based on graph learning to explore the mega-city region structures from multi-source data. An example of clustering analysis consists of the people flow network, cargo flow network, and information flow network, covering 88 cities from Beijing, Tianjin, Hebei Province, Shandong Province, Henan Province, Jiangsu Province, Anhui Province, Shanghai, and Zhejiang Province in China is used to illustrate the applicability of the idea in super mega-city region scale studies. Utilizing the proposed clustering method, a unified network representation is calculated, and 5 mega-city regions, Beijing-Tianjin-Hebei Cluster, Henan Cluster, Shandong Cluster, Shanghai-Jiangsu-Anhui Cluster, and Zhejiang Cluster, are detected based on intercity flow networks. City-to-city flows, including Luan-Taizhou, Lianyungang-Chuzhou, and Xuzhou-Bengbu of the people network, Shanghai-Hangzhou, Suzhou-Shanghai, and Shanghai-Ningbo of the cargo network, Shanghai-Hangzhou, Bozhou-Jinhua, and Huaibei-Bozhou of the information network, are suggested to be further enhanced to facilitate the ongoing nationwide constructions of urban agglomerations in China. The multi-view clustering method proved to be a helpful calculation framework for mega-city region analysis, which would also be considered as a substantial foundation for further urban explorations with more advanced graph learning techniques.

Revealing multi-scale spatial synergy of mega-city region from a human mobility perspective

ABSTRACT Spatial synergy is strengthened integration and connection between cities in a mega-city region, transcending administrative boundaries. The central flow theory suggests that the mega-city regions are formed by the interconnected flows of people across cities, making the spatial synergy can be measured by assessing the aggregation and intensity of flows and interactions between cities and regions. Human mobility data, such as mobile phone data and social media check-ins, enable the tracking of human movements, thus facilitating the transition of central flow theory from theoretical constructs to empirical research. To this end, this study presents an alternative data-driven framework to reveal the multi-scale spatial synergy of mega-city regions from a human mobility perspective. It uncovers homogeneously spatial communities with high inter-city integration using community detection. Strong internal spatial connections of 2.13 billion mobility are filtered using network backbone extraction. An experiment in the Pearl River Delta (PRD), China, demonstrates a multi-scale and multi-core hierarchical spatial synergy in the PRD region. The detailed findings are as follows: (1) Three cities attract the majority of human mobility. Mobility distance is short in urban centers and long in suburban areas. (2) The spatial integration pattern shows the detected communities reveal the hierarchical integration pattern with three main integrated regions: Guangzhou-Foshan-Zhaoqing, Shenzhen-Dongguan-Huizhou, and Zhuhai-Zhongshan-Jiangmen. (3) The spatial connection pattern illustrates the close ties of 9 cities and three core cities, including Guangzhou, Shenzhen, and Foshan. These results provide a human-centric understanding of urban synergy and deeper insights into central flow theory, which supports cooperative development in mega-city regions.

Identifying the spatio-temporal dynamics of mega city region range and hinterland: A perspective of inter-city flows

Mega city regions (MCRs) have emerged in many countries in the process of urbanisation. Understanding the spatio-temporal dynamics of MCRs is crucial for sustainable urban development. However, the spatial scales and boundaries of these MCRs remain poorly defined, and their temporal dynamics have received limited attention. To address these gaps, we propose a new framework and GSMA algorithm that considers inter-city flows to identify MCRs' central cities, ranges and hinterlands. By utilising comprehensive data of over 30 million inter-city flow records covering 369 cities from Amap and Tencent, calibrated with official data from the Ministry of Transport, we identify 10 MCRs and 16 central cities in China, providing a clearer understanding of the spatial ranges and core areas of MCRs. We find that MCR ranges show relative stability during routine activities and expansions during holiday periods. Compared with previous methods, the proposed framework and algorithm have two prominent advantages. First, our methodology incorporates the directional characteristics of flows into the identification of MCRs' central cities. Second, we strike a balance between enlarging regional influence and tightening the internal connections in MCR delineation. In addition, by incorporating temporal changes in inter-city flows, the study reveals the temporal dynamics of MCRs which reflects the intricate interplay between human activities and urban system dynamics.

FDI and industrial development in a mega-city region: a modelling study on the Pearl River Delta

ABSTRACT Foreign direct investment (FDI) and regional development are mutually interwoven phenomena. This paper introduces an analytical framework to investigate the interaction mechanism between FDI and regional industrial structure. This framework posits first that FDI generally has a significant influence on the industrial structure in the region concerned, specifically through intervening mechanisms such as capital supply, active selection, passive competition, product linkage, imitation and demonstration and employee flows. Secondly, the industrial structure, in turn, also affects FDI flows through mechanisms including market demand, factor supply and policy or institutional factors. Finally, there are bi-directional interactions; using a spatial interaction framework, the present study applies and tests a simultaneous equation model and a spatial Durbin model to analyse empirical data from 15 urban regions in the Pearl River Delta mega-city region (PRD) in China spanning the period 2005–2018. The key findings from this multi-scalar analysis are: (i) there are substantial interactive effects between FDI and industrial structure, with the rationalisation and upgrading of the industrial structure significantly promoting FDI inflows into the PRD; (ii) FDI inflows, in turn, contribute to the reinforcement and upgrading of the industrial structure in the PRD; and (iii) the interactions between FDI and industrial structure exhibit significant spatial-economic growth effects. We also find that moderator factors, including independent R&D level, market size, marketisation level, labour cost, infrastructure and government expenditure, have discernible impacts on FDI inflows and the rationalisation and upscaling of the industrial-economic structure in the area concerned. Finally, we note that, in our study, significant spatial dependence effects among urban areas inside the PRD area are observed and modelled. The discussion of the empirical findings leads to the identification of several important policy implications and lessons for regional development strategies from an FDI perspective.

Spatially resolved air quality index prediction in megacities with a CNN-Bi-LSTM hybrid framework

Monitoring pollution in megacities is challenging due to their vast urban expanses and numerous pollution sources. To address this, cutting-edge deep learning models are proposed for monitoring, managing, and forecasting pollution levels. In this study, data concerning six pollutants (O3, NO2, CO, SO2, PM2.5, PM10) and Air Quality Index (AQI) values were collected over a five-year period from three distinct zones within the Tehran megacity. The gathered data were incorporated into a dataset comprising 37,044 records, encompassing the concentrations of examined pollutants and the related AQI across various study points. The primary aim was to enhance the precision of deep learning models using a regional strategic separation approach. A frequency domain filter method was employed to address data noise. Four models—Long Short-Term Memory (LSTM), Bidirectional LSTM (Bi-LSTM), Convolutional Neural Network with LSTM (CNN-LSTM), and Convolutional Neural Network with Bidirectional LSTM (CNN-Bi-LSTM)—were developed to predict AQI values. Evaluation showed disparities in pollution levels among the studied areas. The CNN-Bi-LSTM model exhibited the highest accuracy at 97 %, but challenges in predicting sudden fluctuations reduced accuracy to 95 % in some cases. However, the model consistently captured the underlying pattern of changes. Segregating megacity regions enhances accuracy in forecasting air pollution conditions.

Prospects for a Megacity Region Transition in Australia: A Preliminary Examination of Transport and Communication Drivers

Australian governments continue to search for a model capable of planning future urban settlements at an extended spatial scale (the mega-metropolitan region) to accommodate high population growth more sustainably. Attempts at decentralisation over the past half century have failed, as state capital cities continue to sprawl in an unsustainable manner and increase their primacy at the expense of regional cities. This paper examines how two technologies, broadband and fast rail—both infrastructures capable of re-shaping space–time relationships—could underpin a transition of Australia’s largest capital cities into megacity regions by functionally integrating regional cities into their core metropolitan agglomerations. With the Melbourne megacity region as a spatial framework, changes in population and economic development are examined for Melbourne and several regional cities in Victoria following the introduction of regional fast rail (RFR) and broadband. The impact of high-speed rail (HSR) for intercity corridors in southeast England is analysed as a possible analogue for future application in Victoria. The results revealed that RFR primarily served to extend capital city suburban development. Only HSR had the capacity to ‘punch through’ and boost growth for ‘basic’ new economy industries in ‘on-line’ urban centres in corridors linked to London. High-speed broadband proved most attractive to Melbourne’s agglomeration of high-skilled information workers. Lower speed broadband services were more uniformly taken up across all centres. This discussion speculates on the impacts of these and other green economy and digitalisation drivers on prospects for a future megacity region transition in Victoria.

Food supply networks in the Pearl River Delta mega-city region: Characteristics, resilience and security strategies

Food supply networks in the Pearl River Delta mega-city region: Characteristics, resilience and security strategies

메가시티 서울 담론을 통한 서울 확대론에 대한 논고

This paper is supposed to review critically the arguments for expanding the administrative area of Seoul City, focusing on the Seoul Megacity initiative sparked recently by the ruling party on Korean Political arena. The nuts and bolts of the initiative are letting Seoul to be a Megacity by enlarging it's administrative area, and to fix up the mismatch problems in living areas and strengthen Seoul's urban competitiveness. And as it's typical models, Tokyo Metropolis, Osaka Prefecture, Greater London, and Grand Paris were frequently brought up. Therefore, the task of this paper is to examine what a megacity is and whether it really means expansion of Seoul's administrative district. In addition, it is discussed whether it is contextually consistent with the cases of Tokyo, Osaka, London, and Paris. As the claimants of “Bigger Seoul” are clamouing for, Megacity as a single large city mainly refers to super large cities in developing countries and is associated with urban problems such as slums. Additionally, Tokyo and Osaka were established through the Prefecture-Abolishing processes of Japan in 19th Century, not the urbanization process. Moreover, Greater London and Grand Paris take charge of only wide range functions while leave the functions for small cities to the many cities and small municipalities under the bigger government. So they have nothing to do with expanding the administrative area of their central cities. For the competitive of large cities, the lingkage-oriented concepts like city-region, mega-city region or megaregion are more suitable, than the size-oriented one like megacity.

Associations between Land-Use Patterns and Cardiovascular Disease Mortality in the Beijing—Tianjin–Hebei Megacity Region

Megacity regions where human activities are intensive are key areas for CVD prevention and control in China. Optimizing land-use patterns has been widely recognized as an important public health intervention. Ecological space, agricultural space, and construction space are three basic management objects in China’s new land-use management system. Given that most existing studies focused on a single type of land use, this study treats them as a whole and not only explores the impact of each type, but also systematically investigates the effects of the interactions between any two types of land use and the whole land-use pattern. Specifically, this study first constructs a hierarchical index system, then uses spatial error models (SEM) to explore the global associations between each index and age-standardized CVD mortality rates (ASMRs) and uses the multiple geographical weighted regression model (MGWR) to explore the spatial heterogeneity of factor effects. The possible association between land-use patterns and CVD mortality is then explored, and recommendations for policy formulation are provided. The analysis results show that the overall pattern of moderately decentralized and organically combined land use can control CVD mortality to a certain extent, but the specific influence mechanisms show significant differences according to different land-use types, relationships, and location conditions. First, in terms of single-type land-use distribution, the concentration of ecological space has positive health benefits, while a too high concentration of agricultural space has negative effects. Second, the combination of different types of land use has a significant association with CVD, in which the mixed layout of ecological and agricultural space helps to suppress CVD, while ecological and construction space need to be appropriately regularized and should not be too interspersed. Third, the same index may have different effects in different regions, suggesting that policy makers need to tailor their policies to local conditions.

Metropolitanization through making ‘new metropolitan plans’ in China

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.

Assessing the Foodshed and Food Self-Sufficiency of the Pearl River Delta Megacity Region in China.

Food self-sufficiency has long been regarded as essential for understanding and managing urban and regional food systems; however, few studies have examined the food self-sufficiency of megacity regions within a comprehensive framework that distinguishes different types of agricultural land (i.e., arable land, horticultural landscapes, and waters). To fill these gaps, we took the Pearl River Delta as a case study and quantified the foodsheds of different types of agricultural land by calculating the land footprint of food consumption. On this basis, food self-sufficiency is defined as the ratio of available and required agricultural area for regional food demand. The results indicated that the self-sufficiency level provided by the arable land in the Pearl River Delta is low and cannot realize self-sufficiency at the regional and urban levels. The horticultural landscapes can provide self-sufficiency at the regional level, whereas the regions with water cannot, as their foodsheds extend over the boundary of the Pearl River Delta. For arable land, establishing a localized regional food system requires expanding the foodshed size. These findings provide evidence that megacity regions may face increasing difficulties in achieving self-sufficiency in the near future. This research can improve policymakers' understanding of the sustainability and resilience of regional food systems in megacity regions.

Roles of accessibility and air-rail intermodality in shaping mobility patterns in mega-city regions: Behavioural insights from China

This paper aims to understand mobility patterns in mega-city regions from perspectives of accessibility and air-rail intermodality. Travellers' preferences for intercity mode and its access and egress modes were simultaneously collected in the context of the Beijing-Tianjin-Hebei mega-city region. The accessibility of transport hubs and destinations was measured to enable interpreting mobility behaviour in three dimensions, i.e., travel mode decisions, departure transport hub decisions, and transport service decisions. The calibrated behavioural model highlights a series of determinants regarding level-of-service attributes, travel characteristics, accessibility, socio-demographics, and their interaction. Based on the behavioural insights, twenty domestic cities were selected as destinations for analysing the dynamics of mobility patterns in terms of the competition within the multi-airport system and air-rail cooperation potential in the long-haul market. The elasticity of shifts in transport demand between the primary and secondary airports in the Beijing multi-airport system was assessed under various pricing strategies, highlighting the vital role of the most accessible airport in air traveller decision-making. Moreover, the results underline the effect of air-rail intermodal service upgrades, e.g., offering baggage handling systems and flexible tickets, on stimulating air-rail intermodal mobility in the mega-city region.

Utilizing a top predator to prioritize site protection for biodiversity conservation

Ongoing global change makes it ever more urgent to find creative solutions for biodiversity preservation, but prioritizing sites for protection can be challenging. One shortcut lies in mapping the habitat requirements of well-established biodiversity indicators, such as top predators, to identify high-biodiversity sites. Here, we planned site protection for biodiversity conservation by developing a multi-scale species distribution model (SDM) for the raptorial Northern Goshawk (Accipiter gentilis; goshawk) breeding in an extensive megacity region of Japan. Specifically, we: (1) examined the determinants of top predator occurrence and thus of high-biodiversity value in this megacity setting, (2) identified the biodiversity hotspots, (3) validated whether they actually held higher biodiversity through an independent dataset, and (4) evaluated their current protection by environmental laws. The SDM revealed that goshawks preferred secluded sites far from roads, with abundant forest within a 100 m radius and extensive forest ecotones suitable for hunting within a 900 m radius. This multi-scale landscape configuration was independently confirmed to hold higher biodiversity, yet covered only 3.2% of the study area, with only 44.0% of these sites legally protected. Thus, a rapid biodiversity assessment mediated by a top predator quickly highlighted: (1) the poor development of biodiversity-friendly urban planning in this megacity complex, an aspect overlooked for decades of rapid urban sprawl, and (2) the extreme urgency of extending legal protection to the sites missed by the current protected area network. Exigent biodiversity indicators, such as top predators, could be employed in the early or late stages of anthropogenic impacts in order to proactively incorporate biodiversity protection into planning or flag key biodiversity relics. Our results confirm and validate the applied reliability of top predatory species as biodiversity conservation tools.

Spatial relationship of city branding strategy adoption in megacity regions: Patterns and influencing factors

With the rapid economic growth of regions, cities have adopted various city branding strategies in competitive and occasionally cooperative relationships with other cities. Intercity connections or regional context influence city branding strategy adoption, a topic that has been neglected by previous research on city branding. The spatial relationships of city branding strategy adoption is a worthy topic due to preliminary signs of the relevance of such connections or relationships. This paper explores the spatial relationship of city branding strategy adoption in megacity regions from two perspectives: patterns and its influencing factors. Regarding patterns, megacities regions have shown spatial relationships in different city branding strategy adoption in both within and cross-regional comparisons. Considering influencing factors, this study finds that city branding strategy adoption in the three megacity regions has spatial correlations by using the spatial analysis method, while city branding strategy adoption in the same region tend to be influenced by economic or urban factors in similar ways. Thus, policymakers need to consider these spatial relationships in city branding designs and pay attention to the factors influencing city branding strategy adoption in their own regions.

Urban Networks in the Yangtze River Delta from the Perspective of Transaction Linkages in Manufacturing Industries: Characteristics, Determinants, and Strategies for Intercity Integration Development

In recent years, manufacturing development has received renewed attention from developing and developed countries alike. As mega-city regions (MCRs) are where manufacturing industries converge, the research on urban networks of MCRs under the dominance of manufacturing transaction linkages is currently insufficient. Based on the buyer–supplier linkages of listed manufacturing firms, this paper investigated the characteristics of the urban network in the Yangtze River Delta region (YRDR) in China using the social network analysis method; explored the determinants of nodal centrality and city dyads of the urban network by the stepwise regression and quadratic assignment procedures, respectively; and proposes a “characteristics-determinants-strategies” technical framework for the analysis and optimization of interurban collaboration in manufacturing transactions within MCRs. The findings were as follows: (1) The characteristics of the urban manufacturing transaction networks differed from those of transaction linkages of advanced producer services (APS) firms, intra-firm organization hierarchies, and innovation cooperation networks; (2) the network and geographical “core-periphery” structure of urban power and the circulation corridor of the urban manufacturing transaction network was formed within the YRDR; (3) cooperation parks, innovation collaboration, high-speed rail (HSR) linkage, and geographical proximity between cities were found to facilitate the formation of urban manufacturing transaction networks, and the similarity of industry structures and driving distance between cities inhibits the network; (4) the number of urban industrial firms, GDP per capita, and city government spending on science and technology contributed to the centrality of a city in urban manufacturing transaction networks, while the urban population in a city had a negative impact. The research provides a complementary perspective to the urban network research of MCRs under the perspective of production factors and product circulation and provides policy and urban planning insights for the synergistic development of interurban manufacturing in MCRs.

Metropolitan governance in the context of dynamic urbanization: the case of Brazil

This study discusses the evolvement of metropolitan governance in Brazil and uses greater São Paulo as an in-depth case study to demonstrate how metropolitan governance is organized in a megacity region in the Global South. This is of interest as many publications in this specific academic field focus on European or North American city regions that are, on average, smaller in size and part of multi-level governance systems. Hence, many theoretical positions that are established in the scholarly debate do not work well in the context of megacities. The study will describe how the metropolitan governance arrangement in greater São Paulo evolved and reflected on the setbacks and success of metropolitan planning and policies in the context of uncertain state support. Metropolitan regions have been established in Brazil by the military regime in the mid-1970s for industrialization and comprehensive top-down planning. After the fall of the regime in the 1980s, the question of metropolitan regions was delegated to the states which created a sort of institutional vacuum and a lack of dedicated policies. In 2018, however, Brazil had 76 institutionalized metropolitan regions but these differ in size and institutional strength. The metropolitan region of São Paulo is the biggest as it comprises 39 municipalities with approximately 20 million inhabitants. However, given the dynamic of expansion, the question of establishing an appropriate scale emerged. Attempts to create a governance arrangement for regional development and strategic planning for the so-called São Paulo Macrometropolis with 172 municipalities and roughly 32 million inhabitants failed. However, in a separate process, over decades, seven metropolitan regions emerged on a smaller scale (the São Paulo Metropolitan Region being one of them). The study is based on a literature review, document analysis (laws in particular), and workshops with Brazilian colleagues that happened within the context of a research project on environmental planning and water governance in the greater São Paulo Metropolitan Region.

Regional Coordinated Development in the Megacity Regions: Spatial Pattern and Driving Forces of the Guangzhou-Foshan Cross-Border Area in China

With globalization and informatization, cross-border areas have become increasingly critical interactive spaces, experiencing rapid development and extensive changes in residents’ cross-border travel, constantly changing the spatial patterns of neighboring cities. However, existing studies lack in-depth discussions of the new spatiotemporal characteristics of human activities, spatial pattern evolution, and the driving factors behind them. Therefore, taking the Guangzhou-Foshan metropolitan area as a case, this paper focus on the analysis of the cross-city travel of residents in these border areas in 2019, and investigated the evolution of spatial patterns and the driving forces in the border area during 1985–2020. We found that, instead of the previous one-way attraction pattern caused by the spread of residence, a large number of cross-city trips for leisure and entertainment purposes emerged, and the one-way unbalanced flow, “Foshan to Guangzhou”, changed to two-way circulation. We also explore the scenario in which the travel behavior of urban dwellers in these two cities considerably interacts with the effect of urban structure to produce the observed mobility patterns. Second, we determined the spatial pattern of the Guangzhou-Foshan region from 1985 to 2020 to be on of spreading expansion, with Liwan District as the central core, connecting to several sub-centers. The cross-border area in the Guangzhou-Foshan region represented a compact, extremely high degree of integration and a well-matched functional space. Third, driven by the forces stemming from the planning guidelines and the improving transportation network construction in the border area, the growth points of the two cities continued to expand toward the borderline regarding integrated development, while the growth axis was mainly in the direction of the city border, urban arterial roads, and subway lines. We concluded with development suggestions for increasing travel interactions and optimizing spatial patterns to build a common vision of the whole Guangzhou-Foshan pattern of integration.

Exploring the relationship between quality of living and green spaces in cities: Evidence from an Indian megacity region of global south

Green space (GS) provides a number of environmental and social benefits to the urban residents and these GS are very crucial for a sustainable urban environment and human well-being. However, spatial distributions of GS are rarely uniform over the space, thus creating green injustice. In this, an attempt has been made to assess the relationship between quality of living (QLI) and GS developing greenness Index (GI) across the urban centers in the Kolkata megacity region (KMR), Eastern India. Eighteen variables under three domains were selected to develop the QLI, and three remote sensing indices were used to develop the quality of GS Correlation anslysis was carried out to assess the relationship between QL and GS. Explanatory factor analysis was used to understand the association between factors affecting QL and GS. The Gini coefficient (GC) was used to measure the spatial equity of GS across urban centers. The findings showed that there was a negative correlation between QLI and GI (−0.278). The urban centers with 'very high' and 'high' QLI were characterized by 'very low' and 'low' GI. Most of the urban centers around Kolkata were characterized by 'very high' and 'high' QLI and 'very low and 'low' GI. GS results showed that there was an inequality of GS distribution across the urban centers in KMR. The findings suggest that GS in the cities should be increased and improved for GS justice by enhancing per capita availability and accessibility.

Revisiting the gravity laws of inter-city mobility in megacity regions

Inter-city mobility is one of the most important issues in the UN Sustainable Development Goals, as it is essential to access the regional labour market, goods and services, and to constrain the spread of infectious diseases. Although the gravity model has been proved to be an effective model to describe mobility among settlements, knowledge is still insufficient in regions where dozens of megacities interact closely and over 100 million people reside. In addition, the existing knowledge is limited to overall population mobility, while the difference in inter-city travel with different purposes is unexplored on such a large geographic scale. We revisited the gravity laws of inter-city mobility using the 2.12 billion trip chains recorded by 40.48 million mobile phone users’ trajectories in the Jing-Jin-Ji Region, which contains China’s capital Beijing. Firstly, unlike previous studies, we found that non-commuting rather than commuting is the dominant type of inter-city mobility (89.3%). Non-commuting travellers have a travel distance 42.3% longer than commuting travellers. Secondly, we developed more accurate gravity models for the spatial distribution of inter-city commuting and non-commuting travel. We also found that inter-city mobility has a hierarchical structure, as the distribution of inter-city travel volume follows Zipf’s law. In particular, the hierarchy of non-commuting travel volume among the cities is more in line with an ideal Zipf distribution than commuting travel. Our findings contribute to new knowledge on basic inter-city mobility laws, and they have significant applications for regional policies on human mobility.

Exploring the factors affecting urban ecological risk: A case from an Indian mega metropolitan region

Assessment of ecological risk (ER) is a key approach to adapting and mitigating ecological deterioration in cities of developing countries. In developing countries, the ecological landscapes such as vegetation cover, water bodies, and wetlands are highly vulnerable due to rapid urban expansion. Therefore, urban ER (UER) assessment and its drivers are crucial to guide ecological protection as well as restoration. This study aims to explore the spatiotemporal pattern of UER and the impact of urban spatial form on UER in the Kolkata Megacity Region (KMR), India. This study developed a UER index and used spatial regression models across the urban centres. The ER has been assessed at city scale as well as grid-scale (2 km × 2 km and 5 km × 5 km) from 2000 to 2020. The results showed that ER has substantially increased over the last 20 years. The urban centres with very high and high ER substantially increased, i.e. from 21.95% in 2000 to 31.70% in 2020. Kolkata and its surrounding urban centres were mostly characterized by very high and high ER. ER was influenced by spatial variables (such as land use and landscapes pattern). However, remote sensing parameters were weakly related to ER. The spatial lag model (SLM) (R2 = 0.8686) was found to be better fit model than spatial error model (SEM) (R2 = 0.8661) and ordinary linear regression model (OLS) (R2 = 0.8641). Thus, the findings of the study can improve research and a comprehensive framework for urban ecological resources and provide a scientific basis for urban ecosystem planning and restoration. In addition to this, it will guarantee the sustainable utilization of urban ecosystems.