The statistical definition of migration in China is attached with its unique household registration (hukou) system, the migrants so defined are also called the floating population. A new analytical paradigm is needed to deal with the complexity of sub-flows in the floating population. The paper classifies five types of the floating population in census context by referring the UN migration criteria, and constructs a new paradigm for analyzing the floating population in China. As a particular provincial-level region (hereafter province) is concerned, the inflow and outflow people belong to different hukou groups balanced by their own counter-flow, namely, inflow vs back-inflow (both have no hukou of the province), outflow vs back-outflow (both have hukou of the province). With the clue of inter-census migration cohort, a sub-flows model is constructed to identify the inter-provincial migration based on the retention rate. The annual retention rate of the inter-provincial migration cohort from 2010 to 2020 is 88.7%. Based on the provincial retention rates, an all-increment table of population change by province in China is made by modelling simulation. The paper surfaces new characteristics of population growth and inter-provincial migration: (1) Provincial population changes are divided into five types, among which the inflow-leading increase type is mainly found in municipalities and the eastern coastal areas, while the fertility-leading increase type and the fertility-overriding increase type are mainly in the western provinces and the agricultural provinces in the middle, and the outflow-overriding decrease type and the outflow-leading decrease type in Shanxi, Inner Mongolia, Gansu and the northeastern provinces. (2) The mechanical growth of population can be divided into four types: rapid increase, equilibrium, outflow-overriding decrease and dual decrease (both hukou and non-hukou migration are negative). A "W"-shaped mechanical growth rate profile from northwest to southeast is found with the equilibrium belt standing in its middle. (3) Population floating is divided into three types. The counter-flows are highly-correlated: inflow rate and outflow rate are negatively correlated while the inflow-back-inflow and outflow-back-outflow are significant positively correlated. The analytical paradigm and model of floating population in China can be further extended to the study of "citizenship seeking migration" including international migration, and even further to identity migration including migrations with status changing such as enrollment, employment and marriage.

Evolutionary economic geography has proposed the principle of relatedness. According to the degree of relatedness, the regional industrial development paths can be divided into related diversification and unrelated diversification. However, the current studies neglect the symmetrical nature of relatedness. According to the degree of symmetry between two related industries, related diversification can be divided into symmetrically related diversification and asymmetrically related diversification. Using Chinese industrial enterprises database from 1998 to 2012, this paper investigates symmetrically related diversification and asymmetrically related diversification's relationship with regional economic complexity. The result shows that: (1) The regional industrial development paths are dominated by related diversification rather than unrelated diversification. The number of related new industries in China accounted for about 60%-70% of the total number of new industries from 1998 to 2012. In terms of related diversification, positively asymmetrically related diversification takes the largest part, while symmetrically related diversification takes the second largest part. The number of positively asymmetrically related new industries accounts for about 60% of the total number of related new industries, and the number of symmetrically related new industries accounts for about 35% of the total number of related new industries over the time period from 1998 to 2012. (2) Industries with higher technological complexity show stronger symmetry in their related diversification, while industries with lower technological complexity show stronger positive asymmetry in their related diversification. (3) Regions with higher economic complexity usually have more unrelated diversification and its related diversification shows stronger symmetry. Regions with lower economic complexity usually have more related diversification and this related diversification shows stronger positive asymmetry. This study can contribute to the development of the principle of relatedness in evolutionary economic geography and provide suggestions for policymakers in terms of the industrial upgrading of regions.

Geographic environment has exerted profound effect on the origin and evolution of world civilizations. Chinese civilization budded and evolved on a vast and varied territory between Yellow and Yangtze rivers, and has been thus deeply affected by the local geographic conditions. But it has been hardly seen to explore the origin of Chinese civilization from the perspective of geography. On the basis of integrated scientific investigation in China's north-south transitional zone, geographic analysis of Neolithic culture distribution and interpretation of pre-Qin and Qin-Han ancient literature, the conclusions can be drawn as follows: (1) The early agriculture pattern of "Rice in the south and millet in the north" and the ancient astronomy formed before about 8000 years were the background for Chinese civilization. The geographic distribution of Neolithic Dadiwan, Yangshao, Majiayao and Longshan culture sites showed that the earliest civilization elements appeared in the upper reaches of West-Hanshui and Weihe rivers, with a spatial trend of spreading toward east. (2) The West Qinling Mts. region, located between the Tibetan Plateau and the Jialing River, especially its inner Chenghui and Xili basins, being characterized by superior natural conditions and resources, is closely related to the three major mysteries concerning the origin of Chinese civilization, i.e., the main areas of the ancient Di and Qiang ethnic groups, the location of ancient Kunlun Mts., and the site of Dayu water control. (3) The Qin ethnic group stepped onto the stage of history by assisting Dayu in water control, and in their history of multiple ups and downs, built the grand water control projects in ancient China, such as the Dujiangyan Irrigation Project, Zhengguo Canal, Lingqu Canal, etc., and pioneered the time of "Books with the same text" and "County system", forming the main line of the origin and early evolution of Chinese civilization. (4) The West Qinling areas are still basically a "blind zone" in archaeological and historical research. It is highly recommended to conduct systematic and in-depth archaeological and historical research in this region so as to realize the breakthrough in the exploration of the origin of Chinese civilization as soon as possible.

Thermokarst lakes, as prominent thermokarst landscapes in permafrost regions, significantly influence ecological vegetation, hydrological processes, and carbon cycling in the Arctic. However, the current understanding of the distribution characteristics and change mechanisms of Arctic thermokarst lakes remains limited. To address this gap, this study employs meta-analysis and mathematical statistical methods to investigate the distribution patterns and dynamics of thermokarst lakes. The results reveal a pronounced spatio-temporal heterogeneity in the distribution and changes of Arctic thermokarst lakes. These variations are closely associated with permafrost conditions, lithology, soil types, subterranean ice content, and soil temperatures. Most Arctic thermokarst lakes are located in continuous permafrost area, where subterranean ice content exceeds 10%, average soil temperatures are above -4°C, and there are specific vertical soil temperature gradients. The change trends of thermokarst lakes differ under various environmental conditions. Generally, the development of thermokarst lakes follows three stages: initial formation, mid-term expansion, and late-stage contraction, all influenced by hydrological and thermohydrological balances. As critical indicators of permafrost degradation and climatic environmental changes, thermokarst lakes profoundly impact carbon cycling, hydrological processes, and ecological environmental changes within the Arctic ecosystem.

New quality productive forces are advanced productivity that is freed from traditional economic growth mode and productivity development paths, features high-tech, high efficiency and high quality driven by technological innovation in the new era. From the geographical perspective, developing new quality productive forces is the ability to coordinate new human-earth relationships in the Anthropocene, where human activities dominate, promote the harmonious coexistence of humans and nature, transform green waters and mountains into gold and silver mines, drive high-quality development and layout, and comprehensively implement the construction of a beautiful China. Geography focuses on studying the emergence and development process, formation and evolution characteristics, spatial organization patterns, and regional differentiation laws of new quality productive forces driven by innovation, so as to promote the human-earth system to enter the ecological civilization stage of highly coupled and harmonious coexistence between humans and nature. Compared with traditional industries, the evolution of new quality productive forces has experienced a fluctuating process of evolution from low-quality productivity to medium-quality, medium-high-quality, and then to high-quality productivity, accompanying the emergence of continuous technological revolutions and industrial revolutions. They exhibit basic characteristics such as high coupling, deep integration, super correlation, rapid iteration, and spatial differentiation. The pivotal directions propelled by the drive of new quality productive forces for geographical research encompass the following: re-coordinating human-earth relationships to foster novel harmonious coexistence conducive to the realization of a beautiful China; restructuring industrial systems to align with the new quality productive forces, facilitating profound industrial transformation; reallocating geographical elements to establish a novel mechanism that harmonizes natural, humanistic, and data-driven components; reshaping spatial pattern to engender a fresh spatial paradigm wherein new quality productive forces and traditional industries are integrated deeply; rebuilding ecological environment to leverage them as green engines of productivity, thus enhancing the intrinsic value of ecological capital; revitalizing geographical science through the refinement and updating of theories and methods, thereby constructing a modern disciplinary landscape of geography.

The empowerment of spatio-temporal information fully releases and amplifies its value as a critical factor of production, meeting the need of the era to support the high-quality development across diverse economic and social sections. Currently, foundational research into the empowerment of spatio-temporal information remains undeveloped, predominantly constrained by the perception that empowerment is synonymous with application. The lack of comprehensive understanding and investigation into its mechanism results in ambiguity in both the connotation and extension of spatio-temporal information, as well as the intrinsic mechanism of its empowerment. Such vagueness restricts the empowerment in a scientific and efficient manner. There is an immediate necessity to delineate its fundamental essence, mechanisms of empowerment, and operational modes clearly. To address the aforementioned challenges, this paper defines the foundational concept, explores the rich connotation, and outlines the essential characteristics of spatio-temporal information. It posits that entropy serves as the physical foundation for the empowerment of spatio-temporal information, with entropy decrease acting as its inherent driving force. The empowerment of spatio-temporal information utilizes spatio-temporal information as the medium, driven by the negative entropy flow, marked by the transformation of inherent uncertainty. This process enhances both the system's structure and performance through the dynamic interplay among humans, machines and the external environment. This paper describes three empowerment modes of spatio-temporal information: taking spatio-temporal information as the in-itself information for direct empowerment, employing it as the being-itself information for indirect empowerment, and converting it into spatio-temporal knowledge for enhanced empowerment. Lastly, this paper investigates the pathways through which the empowerment of spatio-temporal information contributes to the high-quality development of natural resources.

Glacial meltwater is a major carrier of nutrients and bioactive compounds, and meltwater chemistry is an important way to study the glacier drainage system and its dynamic characteristics to gain insights into the biogeochemical cycling process and explore the relationship between deglaciation and climate change. With accelerated melting of glaciers and increases in erosion and weathering, meltwater chemistry has undergone significant changes, which may have significant impacts on downstream water quality, the water environment, and ecosystems. In this study, the contents of inorganic chemical components and their spatial and temporal variations, solute sources and their proportions, and the relationship between chemical weathering and carbon cycling in global glacial meltwater were reviewed. The results indicated that meltwater chemistry is affected by various factors, such as the nature of the bedrock, the drainage system, the physical chemistry, and the topography and geomorphology. To provide references for future research on the relationships among the cryosphere, carbon cycle, and climate change, it is essential to strengthen simultaneous and continuous monitoring of hydrometeorological parameters and inorganic and organic chemical components in meltwater, evaluate the ecological and environmental effects of solutes sourced from glaciers, and examine the relationships among the coupled mechanisms of chemical weathering in glacial regions, solute mobilisation, and atmospheric CO₂ balance.

The quality of development is crucial for China to comprehensively build a socialist modern country. Drawing on related concepts of development in quality, the paper conceptualizes a city in high-quality development and proposes a stylish framework with five dimensions to evaluate it, in line with the New Development Philosophy, which is composed of innovation, coordination, greenness, openness and sharing. Using the methods of spatial analysis, club convergence test and spatial Durbin model, the paper identified the spatial evolution of the quality of city development in China and associated determinants during 2005-2020. On average, the level of city development quality increased by 48.4% during the study period. The number of cities at low-level of quality in development decreased dramatically, accompanied by a profound transformation in the spatial pattern of city development quality, which presents significant spatial aggregation. The spatial imbalance remains for cities with different development qualities, and the challenge is still huge to narrow the gap. With significant role differentiation among cities, a "pioneering-catching up" pattern emerges, and the 11 pioneering cities such as Beijing, Shanghai and Shenzhen have become the pioneers of high-quality development in China. Key determinants for cities achieving high quality in development includes urbanization level, public investment, digital economy, environmental regulation and economic growth, while there is inverted U-shaped relationship between city size and development quality. To achieve the goal of high-quality city development in the new era, it is necessary to focus on the development of cities in the central and western regions, making full use of the demonstration role of pioneers, promoting quantitative growth, strengthening environmental regulations, cultivating the new forms of digital economy, and optimizing the city size hierarchy.

County has long been the basic unit of national governance in China. Yet, only limited policy attention has been paid to counties. Recently, the central government proposed to carry out county-level urbanization to further deepen the people-centered new urbanization strategy. In this situation, counties need to provide enough jobs and decent income for rural emigrants. However, this is only the case for a small fraction of counties with prosperous local economies, and most of the rest counties need to enhance their industrial development to absorb the rural emigrants. Since China's industrialization process is largely influenced by the government, boundary adjustment, such as turning counties into urban districts, may also influence the local industrial development in various ways. Relying on the National Annual Survey of Industrial Firms Database (1998-2015), this paper constructs a county manufacturing industry dataset with 1110 counties and 376 four-digit level industries. With an Evolutionary Economic Geography approach, this paper explores the causal impacts of turning counties into districts on counties' manufacturing upgrading by employing difference in differences in differences method (DID). The empirical results show that, first, after turning counties into districts, counties have higher probabilities to enter more complex industries and exit less complex industries. And in both cases, the impacts of turning counties into districts has a time lag. Second, at the macro county level, turning counties into districts could benefit manufacturing upgrading through population agglomeration, economic development, infrastructure construction, and public service improvement; at the micro firm level, turning counties into districts could upgrade manufacturing industries by promoting output, intermediate inputs, profit, innovation, and tax reduction. Turning counties into districts has the largest impact on manufacturing upgrading in the eastern region and has negative impact in the central region. These findings could not only provide empirical support for the future implementation of turning counties into districts, but also enrich the institutional perspective of Evolutionary Economic Geography on regional industrial evolution.

Geography, as part of earth science, is a complicated system composed of multiple disciplines. Interdisciplinary studies are the significant characters of geography. With the rapid development of low-altitude airspace exploitation such as the application of UAV, low-altitude airspace has become a subject of research field of geography. Recently, there are many interdisciplinary studies and integration between geography and aeronautics. However, it is a difficult and innovative task to take the low-altitude airspace as a fixed research object of geography and develop it into a branch of geography named low-altitude airspace geography. In this paper, we consider the low-altitude airspace as a complex giant system, which has two geographical characteristics of synthesis and regionalism. Herewith, low-altitude airspace is a research object of geography in theory, which is the basis of generation of low-altitude airspace geography. The development trend of low-altitude airspace geography is to deeply conduct interdisciplinary studies with aeronautics, physical geography, human geography, information geography. On the basis of analyzing the relationship between low-altitude airspace geography and the above-mentioned disciplines, we tentatively proposed the preliminary layout of the discipline system of low-altitude airspace geography, which is composed of integrated low-altitude airspace geography, departmental low-altitude airspace geography and low-altitude airspace information geography. This paper aims to promote the development of low-altitude geography as a new academic growth point of geography to some extent.

The Hengduan Mountains Region is one of the regions with the most densely distributed and severe flash flood disasters in China. It is also the key area for major engineering projects and beautiful countryside construction in southwest China. However, previous studies have not systematically summarized the development characteristics and formation modes of flash flood disasters in this region, which restricts the development and establishment of flood control theory and technical system in the southwestern mountains. This paper focuses on the physical processes of generation, movement and hazard-formation of flash flood disasters in the Hengduan Mountains. It clarifies the dominant disaster-inducing conditions (multiple humid monsoon circulation conditions, high potential energy conditions and high heterogenous underlying surface conditions) and disaster development characteristics (high spatio-temporal heterogeneity, highly concentrated energy, disaster chain and clustered occurrence) of flash floods in the Hengduan Mountains. Based on the entire processes of flash flood disasters, three major formation modes are summarized: the runoff generation of vegetation-hydrology-soil coupling dominated by high hydraulic gradient in mountainous areas, strong runoff-sediment coupled movement, and serious disaster losses due to high exposure of disaster bearing objects. Finally, based on the issues in previous research, four future research challenges for flash flood disasters in the Hengduan Mountains are proposed. Our work contributes to the development of disaster prevention and reduction research, including basic theoretical system, precise risk assessment of regional disasters, and fine early warning and forecasting of flash floods.

According to the strategic direction of urban-rural integration and rural revitalization, the spatial reconstruction of rural settlement system is the spatial organization foundation of future urban-rural integration development. This paper focused on the hierarchical scale and spatial organization characteristics of the rural settlement system. It comprehensively revealed the evolution process and regional characteristics of rural settlement systems of 111 administrative units in Guangdong province from 1990 to 2020, and discussed their evolutionary mechanism and spatial optimizing and reorganizing regional modes. The results show that: (1) There were significant regional differences in the hierarchical scale distribution of the rural settlement system in Guangdong. The patches of rural settlements show the characteristics of concentric aggregation and distribution centered on the geometric barycenter of each administrative unit. The spatial distribution pattern of the rank cumulative size coefficients of rural settlement system was "high in the southwest, but low in the northeast" and "high in coastal areas, and low in the inland". The decreasing region of the rank cumulative size coefficient was concentrated on the east bank of the Pearl River Estuary and coastal areas of eastern Guangdong, while the increasing region was mainly distributed on the west bank of the Pearl River Estuary. (2) The influencing factors such as natural background, economic development, urbanization development, transportation and location, institutions and policies jointly drove the development and evolution of the rural settlement system. Rural settlement system of urban areas is small in scale in the mature stage of urbanization, which will gradually die out and integrate into the city. Driven by urbanization, industrialization and policies, rural settlement system of suburban areas has experienced survival of the fittest and maintains a stable scale, but the mixed distribution of urban and rural land makes the spatial organization of rural settlements increasingly loose. Driven by the continuous outflow of production factors, exurb rural settlements appear to be "hollowing out". The villagers returning to build new houses and the lack of homestead exit mechanism have led to a continuous and stable growth in rural settlement scale, and their spatial distribution is characterized by more peripheral diffusion. Rural settlement system with poor location in mountainous areas develops slowly under the support of policies, and the aggregation characteristic along the transportation line is significant. (3) Facing the integrated development of urban and rural spaces, four models of spatial optimization and reorganization of rural settlement system are proposed: urban-rural integration development, dual-core-driven development, central place hierarchical system development, and pan-center chain-connecting cluster development.

Population equilibrium development is the valuable guide and ideal pursuit of China's population policy and has significant implications for regional equilibrium development. However, there are still misunderstandings about interpreting population spatial equilibrium, and its scientific connotation requires further explanation and promotion. Population spatial equilibrium gives the meaning of space based on population equilibrium, which can be understood as the spatial equilibrium of population distribution. When other factors remain unchanged, the net migration between regions is zero; that is, the total number of immigrants of each region are equal to its total number of emigrants to achieve the dynamic equilibrium of population distribution among regions. A migration stream will exist between regions in an equilibrium state. Migration and equilibrium can coexist, but the population distribution between regions remains dynamic and stable, and the population spatial distribution structure will not change. Specific conditions cause the inherent stipulation of population spatial equilibrium. The equilibrium point will also change with economic, social, resource, and environmental changes. Equilibrium is a relative concept derived from the instantaneous concept; instantaneous equilibrium is an ideal state in the long term. The population spatial distribution is constantly changing from disequilibrium to equilibrium and from equilibrium to disequilibrium. This paper describes a theoretical model of multi-regional population spatial equilibrium based on the regional wage rate, human climate suitability index, urban crowding degree, and distance. Using the Yangtze River Delta as an example, the study analyzes the equilibrium population spatial distribution under current economic, social, environmental, and population conditions. The study found that the population of the study area is concentrated along the river and the coast, mainly in the south of Jiangsu, along the coast of Hangzhou Bay, and the canal from Nanjing to the north of Jiangsu. By comparing the equilibrium population with the current distribution, the Yangtze River Delta can be divided into quasi-equilibrium, attractive, and repulsive areas. The attractive areas, such as Shanghai, Nanjing, and Hangzhou, have large population agglomeration potential. In contrast, the repulsive areas are mainly located in northern and western Anhui, northern Zhejiang, and other areas close to the quasi-equilibrium area. This suggests that under free migration, the population will further concentrate in the areas of Shanghai, Nanjing, Hangzhou, and southern Jiangsu.

With the increasing global warming over the past three decades, the climatic zones and eco-geographical regions characteristics in China have changed. This study used the climatic data of 641 meteorological stations over the past three decades (1991-2020), as well as the high-precision data of eco-geographical elements to optimize the eco-geographical regions in China. The study updated the map of eco-geographical regionalization in China (2023) and increased the scale to 1:4000000. The new map divided China into 11 temperature zones, 22 dry and wet regions, and 50 natural regions. The results show that compared with eco-geographical regionalization in 2007, the overall pattern of eco-geographical regions in China has not changed significantly over the past three decades, but the boundaries of temperature zones, dry and wet regions, and eco-geographical regions (natural regions) in some areas have changed to some extent. Firstly, the boundary change of temperature zones is more obvious in the east. Particularly, in the middle and lower reaches of the Yangtze River, the northward shift of the temperature zone boundary between the northern subtropical and the mid-subtropical zones is obvious. Secondly, the boundary between dry and wet regions has changed, and that between semi-arid and arid regions in the north of the second-order landform step has shifted slightly to the west. In addition, the boundary between semi-arid and sub-humid regions in the Qinghai-Tibet Plateau has shifted slightly to the southeast, reflecting a slight expansion of the scope of semi-arid regions. Finally, boundary changes in natural regions in some areas vary greatly. This study can provide a macro-regional framework for guiding ecological conservation and restoration in different regions.

Social-Ecological System (SES) is a collection of social subsystems, ecological subsystems, and the interactions between them. It is a common difficulty of cross-multidisciplinary fields to predict the changes in human-earth systems and support the relevant management decisions through clarifying the interaction between the ecological environment and human society. The framework of ecosystem service provides a new perspective for revealing the transmission and the role of various elements in SES. Taking ecosystem service as an entry point, this study follows the context of "Ecological System Supply-Ecological Coupling Human Intervention-Promoting Social Development". And the research progress and trends of existing coupling simulation methods related to SES are summarized. This article argues that in the conduction research of the ecosystem services cascade, the academic cognition has emphasized the "impact of natural ecosystem to social-economic system" rather than the "interaction and feedback mechanisms for ecosystems and social systems". In terms of research content, scholars have trsnsformed their focus from "changes in ecosystems and environmental effects" to "social-economic system and the effect on different groups". The focus of research has shifted from the theoretical inquiry of the "internal mechanism and power mechanism" to the applied practice of "optimization and regulation strategy" among the coupling systems. Future research of SES should strengthen the simulation of social-ecological coupling with equal emphasis on nature and humanities. It is the focus of breakthroughs to comprehensively understand the internal interactions and feedback of complex systems.

Economic globalization has reshaped the world economy's spatial pattern while simultaneously changing the context for developing economic geography theories. This study revisited the changing features of economic globalization and investigated its geographical implications. Next, it summarized the new trends in economic geography studies in response to the changing economic globalization. Lastly, this study proposed a research agenda for domestic economic geography studies by combining the requirements of global trends and national strategies. The main findings include the following: The scale of geographical integration during economic globalization keeps shrinking, leading to a pattern of regionalization. The driving forces of economic globalization have gradually shifted from cost-saving to innovation. Accordingly, the benefits of economic globalization will be reallocated between developed and developing countries. The trade-offs between efficiency and resilience alter the global value chain, shifting outsourcing from off-shoring to re-shoring or near-shoring. The changing economic globalization has witnessed the rising effects of geographical distances, institutions, and resilience on increasing the inequality of the global economic geography. In economic geography, the scalar structures shifted from the global-local to the global-national-local. The relational networks evolved toward a multi-level, multi-agent, and multi-scale one. The role of the nation has been revisited. More attention has been paid to geopolitical hotspots. Overall, economic geography's institutional, cultural, relational, and evolutionary turns exhibit an emerging trend to convergence. In such a setting, domestic economic geography should find a new balance between global trends and national strategies. This study proposed seven research issues, including: (1) the practice of the Belt and Road and the pattern of inclusive globalization; (2) the economic geography of dual circulation; (3) the paths and resilience of regional development in response to the global production network restructuring; (4) the evolution and competitiveness of industrial clusters; (5) the building of multi-level innovation systems; (6) the regional sustainable development within the global environmental governance system; and (7) the impact of geo-economics on national economic security and interests.

Infrastructure construction reflects the interaction between "human" and "land" in the process of transforming and utilizing the natural environment, whose implementation process involves complex interactions between human and land. With the continuous advancement of China's Belt and Road Initiative, the significantly increased cross-border infrastructure activities on different scales, such as the global, regional, national, and urban, as well as the complex interactions between human and land involved in their implementations, have triggered collisions and conflicts between Chinese and foreign scholars on the geography of infrastructure construction. This paper systematically compares the concerns and research contexts of Chinese and foreign geographic research on infrastructure-related issues, and on this basis, it reflects the key issues of infrastructure research based on the perspective of geography. It believes that infrastructure construction reflects the various purposes and methods of how nature is transformed and utilized by human beings. At present, domestic geographical studies have focused on the economic function of infrastructure construction, while international geographical studies have paid more attention to the heterogeneity of the "human" and "land" involved in infrastructure's concern on human-land relationship. This paper insists that this academic boundary is caused by different demands of the various social development stages on infrastructure, and it is essentially a continuous process. On the basis of comparing the differences in infrastructure studies between domestic and international geography, this paper discusses how the infrastructure corrects and regulates human-land relationships from a more dynamic, multidimensional, systematic, and relational ontology perspective, and then explores the core geographical issues involved in infrastructure under the background of this new and systematic infrastructure ontology. From a theoretical perspective, this paper integrates the ontological differences in infrastructure studies within and outside China and constructs a unified conceptual framework and ontological foundation for effective dialogue between domestic and international geographical studies. From the practical perspective, under the background of "Infrastructure Going First" in China's "Going Globally" strategy, this paper also has important reference value for China's overseas infrastructure construction.

On the basis of analyzing urban SDGs monitoring and evaluation, this paper expounds the conceptual connotation of geospatial enabled monitoring and its differences from traditional statistical-based monitoring for urban SDGs. Meanwhile, through document comparison and analysis, the development and latest progress of urban SDGs monitoring and evaluation has been revealed, suggesting a transformation of urban SDGs monitoring and evaluation from traditional statistical-based monitoring to geospatial enabled monitoring. In addition, this paper systematically analyzes the research progress and current situation of geospatial enabled monitoring from the aspects of monitoring index system, geospatial data acquisition for monitoring, and monitoring ideas and methods. Results showed that the number of urban SDGs indicators is too large and the relationship is complex, with the lack of clear core and key indicators, which need to be optimized and improved according to the specific situation. The lack of standard, public and directly available data requires the development of appropriate methods for spatial data generation and multi-source data utilization, and the establishment of data products for urban SDGs monitoring and evaluation. Besides, the lack of scientific and efficient monitoring and evaluation methods is also one of the main problems facing the current urban SDGs studies. Finally, through the analysis of current challenges in urban SDGs monitoring, future research in geospatial enabled monitoring for urban SDGs are proposed, including the establishment of scientific and efficient monitoring and evaluation methods, the establishment of a standardized and unified monitoring index system, the construction of data production sharing and monitoring and evaluation knowledge service platform, and the strengthening of the application research of big earth data and related disciplines support for the monitoring and evaluation of urban SDGs.

This study focuses on the Lower Yellow River (LYR), which has experienced continuous erosion since the operation of Xiaolangdi Reservoir in 1999, and its complex spatio-temporal variation process. Using the single-step mode of the Delayed Response Model (DRM), we derive a calculation formula for the accumulated erosion and deposition volume in the LYR. The coefficient of determination R² between the simulated and observed values from 2000 to 2020 is 0.99. Currently, the LYR is undergoing continuous erosion, but the erosion rate is gradually slowing down, and the difference between the equilibrium value and the calculated value of accumulated erosion and deposition volume gradually decreases, which means that the riverbed erosion is approaching equilibrium. Additionally, we derive a formula for the spatial distribution of main channel accumulated erosion volume per unit river length in the LYR based on the non-equilibrium suspended sediment transport equation. The coefficient of determination between the fitted value and observed value from 2003 to 2015 is about 0.98-0.99, with a relative error of approximately 6.2%. Our findings suggest that under the current conditions of decreasing sediment inflow and continuous scouring, it takes around 3.0 years for the riverbed to achieve half of the erosion and deposition adjustment and approximately 13.0 years to achieve 95% of the adjustment. Moreover, the spatial distribution of accumulated erosion volume in the LYR tends to become more uniform with the continuous development of erosion. These results provide valuable reference for analyzing the complex spatio-temporal variation process of the LYR.

At present, the empirical analysis of regional dual-nuclei structures at the national level is still relatively rare. How to define the provinces with the characteristics of dual-nuclei structures and analyze their impact needs further empirical discussion. In this paper, the spatial Dubin model and the data of 259 prefecture-level cities are used to analyze the distribution characteristics of regional dual-nuclei structure in China and its influence on provincial development. The empirical results show that 11 provincial-level regions (hereafter provinces) in China show the characteristics of dual-nuclei structure. The regional dual-nuclei structure plays a significant role in promoting the economic development of the province, but the northern and southern regions show great differences. The regional dual-nuclei structure has a promoting effect on provincial industrial agglomeration and helps to promote the improvement of local scientific and technological innovation. In general, compared with some single-core provinces with small scale and weak radiation driving force in some provincial capitals, the regional dual-nuclei structure can make up for these shortcomings to a certain extent by virtue of the number of central cities and spatial distribution, which is more conducive to driving local economic development and scientific and technological innovation.