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    Measure and distribution of urban elderly in poverty: An empirical study in Beijing
    GAO Xiaolu, WU Danxian, YAN Bingqiu
    Acta Geographica Sinica    2020, 75 (8): 1557-1571.   DOI: 10.11821/dlxb202008001
    Abstract1859)   HTML97)    PDF (1994KB)(526)      

    Poverty among older people in urban areas is growing along with population ageing and urbanization in China, but the absence of proper indices and method to measure urban elderly poverty brings difficulty to the understanding of the spatial pattern of elderly poverty in cities and policy making in poverty reduction. It is necessary to consider the association of elderly poverty with education, health, family relationship and social support levels of older people and set poverty cutoff more appropriately. With a factor analysis method, we develop a resource-based poverty index to identify poor older residents on the basis of survey data in eight typical residential communities in Beijing. Then, the elderly poverty rates for different residential communities are estimated and the spatial patterns of urban elderly poverty are investigated. It is found that, (1) resource, health, independence and age factors interpret the variation of older residents, among which the score of resource factor constitutes an appropriate indicator of urban elderly poverty. (2) Elderly poverty rate differs significantly for different types of residential communities. With the spatial distribution data of various communities being considered, the poverty rate of elderly population in Beijing is estimated to be 9.55%. (3) The elderly poverty rate of town centers away from the central city is the highest and the poverty rate drops down from the outer to inner areas of the central city gradually. The density of the elderly in poverty, on the other hand, goes to the highest in town centers and the inner city areas, followed by outer central city and the fringe of the central city. These results provide evidences for the formulation of urban policies against elderly poverty in the city.

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    Relief degree of land surface and its geographical meanings in the Qinghai-Tibet Plateau, China
    FENG Zhiming, LI Wenjun, LI Peng, XIAO Chiwei
    Acta Geographica Sinica    2020, 75 (7): 1359-1372.   DOI: 10.11821/dlxb202007003
    Abstract1741)   HTML92)    PDF (4161KB)(775)      

    Relief degree of land surface (RDLS) is one of the key indicators in the fields of suitability assessment of human settlements (SAHS) as well as resources and environmental carrying capacity (RECC) evaluation at the regional scale. Currently, there is still a lack of in-depth research on the determination of the optimal window size for the RDLS calculation and evaluation and its correlation analysis with two topographical parameters, e.g., elevation and relative height difference. These issues further affect the effective representation of the RDLS in the delineation of local to regional topographic relief. Therefore, an objective understanding of the RDLS in the Qinghai-Tibet Plateau of China greatly contributes to promoting the construction of national ecological security barrier and regional green development. In this study, based on the 30 m Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM Version 2), the optimal window size for calculating and evaluating the RDLS in the Qinghai-Tibet Plateau was accurately determined using the average change-point method, and the first 30 m RDLS thematic map for the Qinghai-Tibet Plateau was generated accordingly. Next, the interrelation between the RDLS and elevation and relative height difference was quantitatively examined. Based on that, the effective representation or geographical meanings of the RDLS in the plateau were defined. The results/conclusions include: (1) The optimum window size for the RDLS calculation and evaluation in the study area based on the 30 m GDEM is a rectangular neighborhood of 41×41 pixels, equaling to an area of about 1.51 km2. The average change-point analysis approach shows that the optimum window size for regional RDLS analysis is unique. (2) The average RDLS of the study area is approximately 5.06, along with over 60% of the plateau ranging between 4.5 and 5.7. On the whole, the topographic relief increases from the northeast to the southwest and west parts. Gentle to small-relief landforms are mostly seen in the Qaidam Basin, the Southern Tibet Valley, and the Hehuang Valley (Yellow and Huangshui river valleys). Also, the differences in the local surface relief in varied latitudinal sections (along the mountain range) are small, while those at longitudinal level are big, showing hierarchical and regular fluctuations (crossing the mountain trending). (3) Correlation analyses showed that different values of the RDLS in the plateau correspond to geomorphic units with different elevations and relative height differences. The profile characteristics of the mountains in the Qinghai-Tibet Plateau based on different terrain reliefs indicate that the height above sea level of low mountains steadily increases first, then experiences sudden rise and severe fluctuation in surface relief, and finally forms the orderly ups and downs of the extreme mountains, e.g., the Himalayas.

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    Progress of applied research of physical geography and living environment in China from 1949 to 2019
    CHEN Fahu, WU Shaohong, CUI Peng, CAI Yunlong, ZHANG Yili, YIN Yunhe, LIU Guobin, OUYANG Zhu, MA Wei, YANG Linsheng, WU Duo, LEI Jiaqiang, ZHANG Guoyou, ZOU Xueyong, CHEN Xiaoqing, TAN Minghong, WANG Xunming, BAO Anming, CHENG Weixin, DANG Xiaohu, WEI Binggan, WANG Guoliang, WANG Wuyi, ZHANG Xingquan, LIU Xiaochen, LI Shengyu
    Acta Geographica Sinica    2020, 75 (9): 1799-1830.   DOI: 10.11821/dlxb202009001
    Abstract1678)   HTML68)    PDF (3064KB)(878)      

    Physical geography is a basic discipline of natural science. Since its research object is the natural environment, it is closely related to human survival and development. China's natural environment is complex and diverse; therefore, according to national demand and regional development needs, physical geographers have also made remarkable achievements in applied foundation and application, making important contributions to the planning of national major economic construction and social development, protection of macro-ecosystem and resources and environment, and regional sustainable development. This paper summarizes the practice and application of physical geography in China in the last 70 years (1949-2019), differences between the natural environment and natural zoning, land use/cover change, natural disasters and risk prevention and control, the process of desertification and its administration, lower-yield field transformation of Huang-Huai-Hai Plain, engineering construction of permafrost areas, geochemical element abnormity and endemic disease prevention and control, positioning observation of natural geographical factors, geographical spatial heterogeneity identification, and geographical detector. Finally, it proposes the future application research directions of physical geography.

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    Modern agricultural geographical engineering and agricultural high-quality development: Case study of loess hilly and gully region
    LIU Yansui, FENG Weilun, LI Yurui
    Acta Geographica Sinica    2020, 75 (10): 2029-2046.   DOI: 10.11821/dlxb202010001
    Abstract1536)   HTML49)    PDF (6060KB)(463)      

    Agricultural geography is the interdisciplinary subject of agricultural science and geographical science, and agricultural geographical engineering is the further deepening and systematic application of the interdisciplinary research of geography and engineering in the field of modern agriculture and rural revitalization, and it is an important material basis to ensure the agricultural high-quality development. With the innovative development of modern agricultural science and technology and human-earth system science, the scientific and technological needs of regional agricultural infrastructure are increasingly strong, and agricultural geographical engineering experiments have become an important task of agricultural engineering technology research and farmland system management. This article expounds the scientific connotation, experimental principles and technical methods of agricultural geographical engineering, and takes the loess hilly and gully region as an example to carry out the experimental research on geographical engineering and discussed the countermeasures for high-quality agricultural development. Results show that: (1) Agricultural geographical engineering experiments mainly include soil and water allocation, soil layer composition, field experiment, ecological protection, geospatial analysis and monitoring for specific regional geographical environment and agricultural development issues, aiming to explore coupling law of resource elements for regional high-standard farmland construction and healthy agricultural ecosystem construction, and establish a sustainable land use system and multifunctional agricultural management model. (2) Agro-ecosystem experiments mainly includes trench slope protection methods, healthy farmland system structure, crop-soil matching relationship, economic analysis of farmland input and output, which aimed to reveals the coupling mechanism and optimal control approach of "crop-soil relationship" by carrying out interactive experiments and field trials for land improvement and crop optimization. (3) Optimization and regulation of crop-soil relationship is the main content of engineering experiment design, which includes six stages: climate-crop optimization, soil-body structure improvement, terrain-crop optimization, soil quality improvement, soil-crop optimization and benefit-crop optimization. (4) The core tasks of the application of agricultural geoengineering technology are to deepen the comprehensive research, reveal the micro-coupling mechanism and establish the engineering test paradigm, and its application path is mainly reflected in three dimensions of time, space, and logic. The geographical engineering experiment of modern agriculture and its application in the new era are conducive to enriching the frontier theories and methodology of agricultural geography, and are of great significance to the advancement of geographical engineering research and the decision-making of agricultural and rural high-quality development.

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    The basic theory and methodology of rural revitalization planning in China
    LIU Yansui
    Acta Geographica Sinica    2020, 75 (6): 1120-1133.   DOI: 10.11821/dlxb202006002
    Abstract1504)   HTML73)    PDF (4130KB)(744)      

    Agricultural and rural modernization is the general goal of the implementation of the rural revitalization strategy. The scientific formulation of the rural revitalization planning is related to the implementation effect of the national rural revitalization strategy. How to establish the basic theory of rural revitalization and develop the methods of rural revitalization planning have become important tasks of academic research and government decision-making. This paper constructed the theoretical model and method system of rural revitalization planning, tried to carry out the main function-oriented zoning, dominant type classification and principal purpose classification of rural regional system, and established the spatial system of rural revitalization planning and its optimal adjustment scheme. This system was applied to the overall rural revitalization planning in Yanchi County of Ningxia. By establishing the principle of rural revitalization planning that sticks to ecological priority, adaptation to local condition, industrial support and urban-rural integration, it put forward that the priority should be given to the development of rural professional cooperation organizations and the mixed economy of villages and towns, and the acceleration of the construction of advantageous industrial system characterized by the industrialization of tan-sheep, day lily, and minor cereals, and highlighted by the wisdom of eco-cultural tourism. Moreover, it was encouraged to give prominence to the position of the central town in space, and form the village organism and housing industry coordination body with the county seat and three key towns as the center of integrated industry development. The typical case study of Yanchi County has shown that the main contents and technical points of rural revitalization planning were embodied in the following four aspects: (1) determining the overall orientation of rural revitalization planning, and clarifying the phased development mode, key areas; (2) developing the county area based on the main function-oriented zoning, leading type classification and main purpose classification system, and exploring the territorial pattern and differentiation rules; (3) establishing the county development mode and industrial system, formulating coordination schemes of different main function-oriented zones, and revealing the spatial configuration and structural relationship of different dominant types; (4) exploring the local association and hierarchical system of each dominant type in its scale and level. The main task of implementing the rural revitalization planning is to promote the formation of a new pattern of urban-rural development with factors gathering, reasonable structure and orderly space in accordance with the objective requirements of "industrial prosperity, ecological livability, rural civilization, effective governance and prosperous life". China is facing great differences in rural development and many problems in transformation. Regional disparities and urban-rural differences determine the complexity, diversity and differences of rural governance and rural revitalization planning. China's rural transformation-urban and rural integration-rural revitalization-high quality development will become the major development logic and new normal in the future. The research on rural revitalization planning in the new era should focus on the overall situation of regional coordination and urban-rural integration, and solve the practical problems of "rural disease", so as to serve the national rural revitalization planning and scientific decision-making.

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    Cited: CSCD(4)
    Evolution processes of the sandbanks in the Zhenjiang-Yangzhou reach of the Yangtze River and their driving forces (from 1570 to 1971)
    YANG Xiao
    Acta Geographica Sinica    2020, 75 (7): 1512-1522.   DOI: 10.11821/dlxb202007013
    Abstract1374)   HTML64)    PDF (5878KB)(473)      

    Under the influence of the changing relationship between the Yellow River and the Huaihe River, the lower reaches of the Huaihe River had gradually drained into the Yangtze River since 1570 AD, and finally became a tributary of the Yangtze River. This transformation added new variations to the evolution of the Yangtze River's fluvial processes by changing the original riverbed features and currents of the Zhenjiang-Yangzhou reach. This article analyzed three surveyed maps, discussed related historical literature and investigated some antique maps to explore the formation and the evolution of the sandbanks outside the estuary of the Huaihe River. Some sandbanks including the Yumin Sandbar and Nanxin Sandbar appeared before the 17th century due to the disintegration of original sandbars such as Tengliao Sandbar,which disappeared during the Chenghua and Hongzhi reigns in the Ming Dynasty (1465-1505 AD). Since the Huaihe River entered into the Yangtze River, the Yumin Sandbar and Nanxin Sandbar had continued to expand and banked to the north along with the newly-formed sandbanks. At last, the northern channel of the Zhenjiang-Yangzhou reach demised and the riverbed transformed from a straightforward bifurcation into a curved one. Accordingly, the formation of meandering flow began to erode Guazhou Town on the upstream concave bank and silt Zhenjiang Town on the convex bank, gradually reshaping the Zhenjiang-Yangzhou reach of the Yangtze River into its current configuration.

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    Geographical missions and coupling ways between human and nature for the Beautiful China Initiative
    GE Quansheng, FANG Chuanglin, JIANG Dong
    Acta Geographica Sinica    2020, 75 (6): 1109-1119.   DOI: 10.11821/dlxb202006001
    Abstract1359)   HTML97)    PDF (1934KB)(598)      

    Beautiful China Initiative (BCI) aims at sustainable development with blue sky and green land, lucid waters and lush mountains, prosperous society and rich people, and harmony between humans and nature. The BCI is a Chinese practice to implement the SDGs 2030 of the United Nations, and an important method to promote the harmonious development between humans and nature and to win the gold and silver mountains by maintaining clear waters and green mountains. Geography, an applied cross-discipline serving the country's socio-economic development, has comprehensive and regional characteristics. Geographers shoulder the historical mission of building a beautiful China, and are duty-bound to take the lead in becoming pioneers and practitioners of the BCI. The theory of pericoupling and telecoupling between humans and nature is the theoretical foundation of the BCI. The interdisciplinary and comprehensive integration of geography is the practical means for the BCI. The complex system simulation and optimization of geography provide a scientific tool for coupling ways between humans and nature of the BCI. The main coupling ways for geography to promote the BCI include: carry out major scientific and technological projects and coupling demonstrations; perform dynamic assessment and monitoring of the coupled human and natural systems for the BCI; draw up the strategic coupling roadmap and the action plan of the 14th Five-Year Plan (2021-2025) for the BCI; build a concept of beautiful land to comply with the objectives of the National Territorial Space Plan of China; develop a comprehensive regionalization of coupled human and natural systems in accordance with local conditions, and build a group of beautiful urban agglomerations and national parks; undertake pilot projects for the construction of Beautiful China and summarize the regional coupling models for the BCI. These coupling paths will ensure that the whole country and each of its provincial-level region are getting closer to the target according to the schedule and roadmap for building a beautiful China, and diverse regions will achieve the overall goals in the competition.

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    Adjustment and optimization of geographical sciences application code of NSFC
    XIONG Juhua, WANG Jia, SHI Yunfei, LI Fei, ZHANG Xinlin, GENG Haopeng, ZHANG Qing, GUAN Dongjie, WANG Tianfu
    Acta Geographica Sinica    2020, 75 (11): 2283-2297.   DOI: 10.11821/dlxb202011001
    Abstract1248)   HTML38)    PDF (2597KB)(185)      

    The adjustment and optimization of discipline application code is an important part and breakthrough point of the task of "science foundation discipline layout reform" of the National Natural Science Foundation of China (NSFC). This paper reviewed the historical evolution of the application code of geography discipline, systematically sorted out the problems existing in the current version of the application code for geography discipline, discussed the framework concept, principles and formation process of the new version (2021 Edition) application code system, and emphatically explained the historical evolution, scientific connotation and discipline orientation of the new application code. Compared with the previous versions, the new version of the application code system has the following four unique features: (1) The logic of the system is more reasonable; the first level code name has been changed from "Geography (D01)" to "Geographical Science (D01)". (2) The disciplines are more integrated by setting the second-level application code instead of the three-level application code, which can better reflect the interdisciplinary integration. (3) The fields are more comprehensive; according to the development trend of disciplines and the needs of economic and social development, codes of emerging disciplines and fields such as "disaster geography", "land science", and "geographic big data and spatial intelligence" have been added to the list. (4) More attention has been given to technology, namely, "geographic observation and simulation tools" are identified to encourage the development of key tools and instruments for the research of geographical issues.

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    Contribution of climatic change and human activities to vegetation NDVI change over China during 1982-2015
    JIN Kai, WANG Fei, HAN Jianqiao, SHI Shangyu, DING Wenbin
    Acta Geographica Sinica    2020, 75 (5): 961-974.   DOI: 10.11821/dlxb202005006
    Abstract1145)   HTML85)    PDF (5439KB)(733)      

    Based on the observed daily temperature and precipitation of the land surface of 603 meteorological stations in China, the Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) 3rd generation dataset, the changing patterns of NDVI in China during 1982-2015 were investigated and the corresponding contributions of the main driving forces, climatic change and human activities, to these changes were distinguished using the methods of trend analysis and multiple regression residuals analysis. The results showed that vegetation recovered in whole China in research period significantly. Shanghai was the single case with a decrease in growing season NDVI in the selected 32 provincial-level administrative regions, while the growing season NDVI in Shanxi, Shaanxi, and Chongqing increased much faster compared with other regions. The climatic change and human activities drove the NDVI change jointly as main forces in China and induced both a rapid increasing trend on the whole and a huge spatial difference. The impacts of climatic change on NDVI change in the growing-season ranged from -0.01×10 -3 a -1 to 1.05×10 -3 a -1, while the impacts of human activities changed from -0.32×10 -3 a -1 to 1.77×10 -3 a -1. The contributions of climatic change and human activities accounted for 40% and 60%, respectively, to the increase of NDVI in China in the past 34 years. The regions where the contribution rates of human activities were more than 80% were mainly distributed in the central part of the Loess Plateau, the North China Plain, and the northeast and the southwest of China. There were 22 provincial-level regions where the contributions of human activities were more than 50%, and the shares of contribution induced by human activities in Shanghai, Heilongjiang, and Yunnan were much greater than those of any other regions. The results suggest that we should focus more on the role of human activities in vegetation restoration in the whole country.

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    Research progress of human-earth system dynamics based on spatial resilience theory
    LIU Yanxu, FU Bojie, WANG Shuai, ZHAO Wenwu, LI Yan
    Acta Geographica Sinica    2020, 75 (5): 891-903.   DOI: 10.11821/dlxb202005001
    Abstract1136)   HTML60)    PDF (1459KB)(578)      

    The concept of human-earth system represents a dynamic structure formed by the interaction between human and earth within a specific region. Considering the complexity of the system, it is necessary to construct a more powerful indicator system to describe the interaction and reflection processes between human and earth systems. The term of spatial resilience can be understood as the overall ability of regional space to absorb, recover or transform natural and social disturbances. Spatial resilience targeted at securing the structural stability of human-earth system, and it also provides a new approach for the shaping of targeted theoretical models and quantifiable indicator system in the study of human-earth system. This study reviews the research progress of spatial resilience from three perspectives, including: ecological policy and ecosystems spatial resilience from a natural perspective; environmental changes and spatial resilience of community production and living from a social perspective and the spatial resilience integrated indicator system from a comprehensive description perspective. Then the article puts forward three important directions of spatial resilience research in China, including understanding the spatial state that guaranteed system sustainability, identifying the spatial thresholds of human-earth system dynamic process, and satisfying the national demands of ecological protection and social development. This study also discusses the spatial resilience indicator system in various human-earth system functional areas from aspects of system structure, function and threshold. By the deepening of the theories and methods of spatial resilience, the human-earth system dynamics can be further understood, so as to improve the regional level accuracy on simulating the socioeconomic, environmental and political paths, and provide key theoretical and methodological support for the decision-making of sustainable development at global, national and regional levels.

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    Characteristics of warming hiatus of the climate change in Northwest China from 1960 to 2019
    LI Zhe, DING Yongjian, CHEN Aijiao, ZHANG Zhihua, ZHANG Shiqiang
    Acta Geographica Sinica    2020, 75 (9): 1845-1859.   DOI: 10.11821/dlxb202009003
    Abstract1103)   HTML49)    PDF (4240KB)(499)      

    The mean global surface air temperature data indicate that there might be a global warming hiatus during 1998-2012. However, whether it existed around the world is still controversial, and the characteristics of the hiatus in Northwest China remain unclear. Based on the in-situ observation data of air temperature from 1960 to 2019, we analyzed the characteristic of hiatus in Northwest China through the cumulative anomaly curve, the Mann-Kendall test, Move-t test, the Yamamoto test and the linear trend estimation. The results showed that the statistically significant change-point of the annual mean air temperature in Northwest China was in 1986, 1996, and 2012, respectively. The air temperature suddenly rose in 1996, and then kept stable from 1998 to 2012. The annual mean air temperature showed an obvious cooling trend by -0.20 ℃ decade-1 in Northwest China from 1998 to 2012. Meanwhile, the annual mean air temperature in winter had the largest decrease rate and that of summer increased. The east of Northwest China displayed the most significant cooling during 1998-2012, and the Tibetan Plateau was still heating up at the same time. The air temperature of Northwest China rose substantially after 2012, especially in winter, and southern Xinjiang experienced the strongest warming during 2012-2019. Generally speaking, the warming hiatus was evident in Northwest China during 1998-2012 except the Tibetan Plateau. Therefore, more attention should be paid to the marked upward trend in air temperature after the hiatus in Northwest China due to the crucial environment.

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    The effects of vegetation coverage changes on ecosystem service and their threshold in the Loess Plateau
    ZHANG Kun, LYU Yihe, FU Bojie, YIN Lichang, YU Dandan
    Acta Geographica Sinica    2020, 75 (5): 949-960.   DOI: 10.11821/dlxb202005005
    Abstract1089)   HTML78)    PDF (3608KB)(631)      

    The Loess Plateau is the core region of the "Green to Grain" Program, which makes it become the most successful example of ecological restoration in China. It is the common demand of both academic research and management practice to analyze the effects of vegetation restoration on ecosystem service and identify the threshold effects of vegetation restoration. However, there still is a research gap in related studies, especially for the thresholds of vegetation in the ecosystem service change at regional scale. In this study, we chose the fractional vegetation cover (FVC) as an index to indicate the vegetation coverage change in the Loess Plateau in 2000-2015, and took soil conservation service, water yield service and carbon sequestration service as indexes to exhibit the ecosystem service changes. The spatiotemporal changes of vegetation coverage and ecosystem services and their interaction were quantitatively analyzed. On such a basis, we further assessed the effects of vegetation coverage change on ecosystem services and quantitatively identified their thresholds. The results indicated that: (1) The vegetation coverage significantly improved in 2000-2015. Meanwhile, the differences of ecosystem service changes were prominent, with the carbon sequestration service getting significant enhancement, soil conservation service getting certain improvements and the water yield service maintaining steady. (2) There are differences among the correlations between vegetation restoration and changes of ecosystem service. The correlation of vegetation coverage-carbon sequestration service was the strongest, followed by that of vegetation coverage-soil conservation service. (3) The vegetation restoration could promote the improvement of the overall level of regional ecosystem service. Furthermore, we revealed the threshold effect in the promotion. The threshold occurrence resulted in the decrease of promotion efficiency of vegetation restoration, with vegetation coverage reaching 44%, 32%, 34% and 34% in forest zone, forest-grass zone, grass zone and grass-desert zone, respectively.

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    The spatial distribution characteristics and influencing factors of Chinese villages
    ZHOU Yang, HUANG Han, LIU Yansui
    Acta Geographica Sinica    2020, 75 (10): 2206-2223.   DOI: 10.11821/dlxb202010012
    Abstract1083)   HTML51)    PDF (6205KB)(429)      

    Village is the object of rural governance and revitalization. It is of great scientific value to carry out the research on the spatial distribution characteristics and influencing factors for comprehensively promoting the implementation of the rural revitalization strategy. This study systematically integrated the multi-source data such as the longitude and latitude coordinates of the village, geo-environment, traffic conditions and socio-economic level, and comprehensively applied spatial analysis, kernel density estimation and Ripley's K-function to describe the spatial distribution characteristics of Chinese villages and identify the influencing factors of village spatial differentiation. The results demonstrated that the evolution of villages follows the life cycle laws of formation, development, stability, decline, and revitalization, which is affected by the natural geographical environment and human, social, and economic factors. The speed, intensity, direction, and outcome of village evolution vary across regions over time. Further analysis results showed that the distribution density of villages in China is 0.353 per square kilometer. Overall, the number of villages in China is larger in the south than in the north, and larger in the east than in the west, and characterized by agglomeration in the southeast and dispersion in the northwest. Villages are most densely distributed in the middle and lower reaches of the Yangtze River and the Huaihe River Basin. With Hu's line as the boundary, the density of villages in the southeast is higher than that in the northwest. The Moran indexes of the kernel density of villages on the scales of province, county and township are 0.580, 0.861 and 0.910, respectively, showing obvious spatial aggregation characteristics. The spatial distribution of villages in each province presents an inverted U-shaped pattern, and the difference is obvious between provinces. The distribution pattern of Chinese villages is the result of the interactive coupling of geographical environment, location conditions, and social and economic factors. The spatial distribution of Chinese villages is relatively concentrated under the conditions of a slope of 6°-8°, an altitude of less than 200 m, rainfall of 1100-1200 mm, average annual temperature of 15-19 ℃, and anthropogenic soil and cultivated vegetation. The spatial distribution of villages is clustered along roads and rivers. The density of villages in the buffer zone of 100-300 m around roads and rivers is the largest, and gradually decreases as the buffer distance increases. Under the background of comprehensively promoting the strategy of rural revitalization, it is urgent to systematically analyze the causes and dynamic mechanism of rural recession, identify the geographical distribution and types of declining villages, and explore the feasible ways and regional models of rural revitalization.

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    Vertical variation of land cover in the Central Himalayas
    ZHANG Yili, WU Xue, ZHENG Du
    Acta Geographica Sinica    2020, 75 (5): 931-948.   DOI: 10.11821/dlxb202005004
    Abstract1069)   HTML57)    PDF (4104KB)(580)      

    The Qomolangma Mountain region within the Central Himalayas is characterized by obvious altitudinal variation, habitat complexity, and land cover diversity. This region is therefore one of the most sensitive areas to climate change in the world. Besides, because this region has the most complete natural vertical spectrum in the world, it is ideal for studying the vertical structure of alpine land cover. Utilizing land cover data for 2010 (30 m resolution) along with digital elevation model outputs, three division methods were defined that encompass the northern and southern slopes of Qomolangma Mountain. These comprised the ridgeline method, the sample transect method, and the sector method. The study investigated altitudinal distributions, similarities and differences, and changes in the degree of land cover on the northern and southern slopes of the Himalayas area using the software ArcGIS and MATLAB tools and division models. The main results of this analysis are listed as follows:
    Firstly, the distribution of land cover in mountainous areas was characterized by an obvious vertical spectrum structure, with the south-six and north-four pattern of vertical spectrum of land cover in the Central Himalayas marked by the influence of human activities. Secondly, zonal distribution was exhibited by forests, grasslands, sparse vegetation, barren land, glaciers, and snow covers from low to high altitudes. It was markedly different in the composition and structure of land cover vertical spectrum between the northern and southern slopes of this mountain area. The vertical spectrum of land cover types on the southern slope was complete and diverse, but it was relatively simple on the northern slope. The study shows that given the same land cover type, the amplitude of elevation distribution on the southern slope was wide, while that on the northern slope was narrow. The distribution of land cover types on the southern slope was low. Thirdly, the results show that the area distribution ratio of each land cover type varied with elevation according to change mode. Vertical distribution patterns of land cover types on the southern and northern slopes were therefore divided into four categories, with glaciers, snow, sparse vegetation, and grasslands conforming to unimodal distribution patterns. The bare land also followed a unimodal distribution pattern on the southern slope, but it followed a bimodal one on the northern slope. Fourthly, all kinds of vertical belt structures and land cover divisions on the southern slope were similar, but they were different from one another on the northern slope due to division methods. In comparison with field survey data, results reported here for the sector method were more in line with the actual situation.

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    Theoretical analysis of "natural-social-trading" ternary water cycle mode in the inland river basin of Northwest China
    DENG Mingjiang, LONG Aihua, LI Jiang, DENG Xiaoya, ZHANG Pei
    Acta Geographica Sinica    2020, 75 (7): 1333-1345.   DOI: 10.11821/dlxb202007001
    Abstract1063)   HTML67)    PDF (2682KB)(656)      

    The continuous and intense human activities have greatly changed the structure, path and driving force of the natural water cycle evolution, which conversely influences the water security of human being. With the process of globalization and market economy, human activities not only affect the artificial development of water and soil resources, but also extend to the economic field. The "flow" of water trade contained in product has become an important internal factor that drives the evolution of the regional water cycle and affects regional water security. Traditional water cycle research, which focused on the watershed scale, is difficult to reveal the linkage, two-way feedback mechanism and co-evolution dynamic mechanism in water cycle among different regions. Starting from the phenomenon of continuous and water-intensive agricultural products export in Northwest China, this research elaborates the phenomenon, the process, the structure and their driving forces of the unitary natural water circular, nature-human society binary circular, and trading water circular within multi-regional social economic complex systems by theoretical analysis. We explicated the theoretical framework for constructing the "natural-social-trading" ternary water cycle in the inland river basin, including mode of process, driving force of water cycle, conceptual model, influencing factors and ecological environment effects. Furthermore, we discussed the frontier of water cycle research in inland river basin based on ternary water cycle model-social hydrology. We advocated that the future study on water cycle and water resources should focus more on the external forces driving the water cycle of the inland river basin and its two-way mutual feedback and co-evolution, providing theoretical references for the decision-making of water security, ecological environment security and ecological civilization construction in inland river basins.

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    Spatial distribution patterns of Pinus tabulaeformis forest and Pinus massoniana forest in Qinling-Daba Mountains and the boundary of subtropical and warm temperate zones
    YAO Yonghui, KOU Zhixiang, HU Yufan, ZHANG Baiping
    Acta Geographica Sinica    2020, 75 (11): 2298-2306.   DOI: 10.11821/dlxb202011002
    Abstract1038)   HTML34)    PDF (4387KB)(429)      

    Qinling Mountains is not only the geographical boundary between North and South China, but also the boundary between subtropical and warm temperate zones. It plays an important role in the geo-ecological pattern of China. However, there is controversy about the specific location of this geographical boundary in academic community due to the complexity, transition and heterogeneity of the transitional zone, as well as the differences in the delimitation indicators and research purposes. To further reveal the characteristics of the North-South transitional zone and clarify the specific location of the geo-ecological boundary between North and South China, combined with SRTM topographic data, temperature and precipitation data, Pinus massoniana forest and Pinus tabulaeformis forest, which represent subtropical coniferous forests in South China and temperate coniferous forest in North China respectively, were chosen to analyze their spatial distributions in the Qinling-Daba Mountains and the climatic conditions at their boundary with the climatic indexes of annual precipitation, the coldest month (January) average temperature, the warmest month (July) average temperature and the annual average temperatures. The results show that: (1) Pinus massoniana and Pinus tabulaeformis forests and the climate indicators of their boundary can be used as one of the vegetation-climate indicators for the delimitation of subtropical and warm temperate zones. The boundary between the subtropical coniferous forest (Pinus massoniana forest) and temperate coniferous forest (Pinus tabulaeformis forest) in Qinling-Daba Mountains is located along the south slope of Funiu Mountain to the north edge of Hanzhong Basin (the south slope of Qinling Mountains) at an altitude of 1000-1200 m, where the climatic indictors are stable: the annual precipitation is about 750-1000 mm; the annual average temperature is about 12-14 ℃; the coldest monthly average temperature is 0-4 ℃; and the warmest monthly average temperature is about 22-26 ℃. (2) It could be more scientifically to delimitate the boundary of subtropical and warm temperate zones in China by comprehensively considering the vegetation-climate indicators. Additionally, the boundary between subtropical and warm temperate zones in Qinling-Daba Mountains should be a transitional zone consisting of the boundaries of coniferous forests, broad-leaved forests and shrubs between subtropical and warm temperate zones. The results provide a scientific basis for the selection of delimitation indicators of subtropical and warm temperate zones.

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    Formation processes and influencing factors of freshwater lens in artificial island of coral reef in South China Sea
    HAN Dongmei, CAO Guoliang, SONG Xianfang
    Acta Geographica Sinica    2020, 75 (5): 1053-1064.   DOI: 10.11821/dlxb202005012
    Abstract1019)   HTML40)    PDF (3021KB)(372)      

    The goal of constructing artificial islands on coral reefs in China is to build ecological habitable islands. The seawater in the artificial islands is gradually replaced by rainfall infiltration, and the freshwater lens formed is an important water source supporting the island ecosystem. The double-layer geological structure is widespread in coral reefs in the South China Sea. Considering the fact that there exists a great large difference in the permeability coefficients obtained using different measurement methods, this study established numerical simulation models for a coral reef island in the South China Sea to simulate the seawater refreshing process. The results show that different permeabilities of the double-layer geological structure of the artificial islands have no obvious influence on the formation time of fresh water on the artificial islands. The permeability of the Holocene coral sand sediment is the main factor controlling the freshwater lens of the artificial reef. The volume of the forming freshwater lens decreases logarithmically with the increase of the permeability coefficient, and the volume of the freshwater lens decreases more significantly with the increase of the permeability of the Holocene sediment than the thickness of the freshwater lens. After the freshwater lens crossed the unconformity surface and entered the Pleistocene reef limestone, due to the sudden increase of the permeability coefficient of the aquifer, the freshwater lens expanded to the horizontal direction and formed the mustached-shape freshwater body in the reef limestone.

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    The influence of China-Europe Express on the production system of enterprises:A case study of TCL Poland Plant
    LIU Hui, GU Weinan, LIU Weidong, WANG Jiao'e
    Acta Geographica Sinica    2020, 75 (6): 1159-1169.   DOI: 10.11821/dlxb202006005
    Abstract1019)   HTML65)    PDF (2745KB)(438)      

    The implementation of the Belt and Road Initiative and the increasing frequency of the China-Europe Express have brought new changes to the production system of enterprises along the Belt and Road regions. On the basis of summarizing the evolution of production system of enterprises, this paper takes TCL Poland Plant as an example to conduct an in-depth study on the characteristics of the plant's current production system and its differences from the original production organization mode, and analyzes the impact of the China-Europe Express on its current production system. Some conclusions can be drawn as follows. (1) China-Europe Express had a great impact on the production system of TCL Poland Plant, which is mainly manifested in the following aspects. First, the transportation of raw materials by China-Europe Express Train improves the time efficiency and shortens the whole supply chain. Second, China-Europe Express acts as a "moving inventory", which realizes the flexibility of raw material inventory and "zero inventory" effect based on the punctual transportation. Third, the time and inventory benefits brought by China-Europe Express speed up the response to European market. The comprehensive benefits brought by China-Europe Express lead to a more punctual and lean production system, meet the diversified needs of consumers on account of product quality and diversification, and improve ability to expand European market. (2) On the basis of abandoning the original "Rigid Mass Production" system, we argue that TCL Poland Plant formed a unique production system—"Global Fluid Just-in-Time" which absorbed the essence of Toyota Production System based on the punctual global transportation of China-Europe Express Train. (3) The differences between the current and the original production systems of TCL Poland Plant are mainly focused on the following aspects: the difference of transportation and storage mode of raw materials, and the changes of production line, production mode and quality inspection organization, etc.

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    Terraces development and their implications for valley evolution of the Jinsha River from Qiaojia to Menggu
    LIU Fenliang, GAO Hongshan, LI Zongmeng, PAN Baotian, SU Huai
    Acta Geographica Sinica    2020, 75 (5): 1095-1105.   DOI: 10.11821/dlxb202005015
    Abstract999)   HTML47)    PDF (4796KB)(489)      

    The valley evolution of the Jinsha River is a research hotspot in the geomorphology, but there is a big dispute on the formation time and the evolution process of the river valley. Fluvial terraces and the correlative sediments contain abundant information about the fluvial valley evolution. Through field investigation combined with Optically Stimulated Luminescence (OSL) and Electron Spin Resonance (ESR) dating, we confirmed that 8 fluvial strath terraces were formed, and then preserved, along the course of the Jinsha River near Hulukou. The formation ages of T6-T1 are 1190±154 ka, 1079±118 ka, 942±92 ka, 816±48 ka, 544±82 ka, and 41±5 ka, respectively, corresponding well with the transition period of MIS. Near the Qinggangba, 5 terraces (T5-T1) composed of the dammed lake sediments are preserved on the hillslope, with ages of 629 ka, 88 ka, 71 ka, 49 ka and 20 ka, respectively, indicating that the Jinsha River valley from Qiaojia to Menggu has been repeatedly dammed by the landslide deposits since the mid-Pleistocene epoch. The valley evolution defers to the model of "cut-landslide-dammed-aggradation-cut". We calculated the incision rate based on the formation age and the height of the strath terraces near Hulukou, and found that the incision rate can be separated into two parts: before 0.82 Ma, the incision rate is 0.56 mm/a; from 0.82 Ma to now, it descended to 0.19 mm/a. We think this transition is induced by the frequent landslide events, which can bring a large amount of sediments to the river valley, and then impound a lake and accumulate sediments upstream, inhibiting the river incision. Synthesized studies of the fluvial terraces indicate that the formation of the modern valley of the Jinsha River may have begun in the late Early Pleistocene.

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    Analytical methods and applications of spatial interactions in the era of big data
    LIU Yu, YAO Xin, GONG Yongxi, KANG Chaogui, SHI Xun, WANG Fahui, WANG Jiao'e, ZHANG Yi, ZHAO Pengfei, ZHU Di, ZHU Xinyan
    Acta Geographica Sinica    2020, 75 (7): 1523-1538.   DOI: 10.11821/dlxb202007014
    Abstract973)   HTML64)    PDF (1385KB)(512)      

    Spatial interaction is a critical basis of understanding human processes on the land surface. Together with spatial dependence, it embodies the uniqueness and relatedness of geographical space, as well as the impact on the embedded geographical distribution patterns. Spatial interaction also has distinctive space-time attributes, and thus it is significant to geographical research. Big data bring new opportunities for the studies of spatial interaction, which enables us to sense and observe spatial interaction patterns at different spatial scales, and simulate and predict their dynamic evolution. This provides great support for the research of human activity regularities and regional spatial structures. In this article, we first demonstrated the relationship between spatial interaction and geospatial patterns, and introduced how to sense spatial interaction with big geodata. Then, we generalized the progress of relevant models and analytical methods, and introduced the corresponding applications in fields of spatial planning, urban transportation, public health and tourism. Some key issues were also discussed. We hope this review can provide guidance for the studies of spatial interaction supported by big data.

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    Spatio-temporal pattern and driving forces of urbanization in China's border areas
    SONG Zhouying, ZHU Qiaoling
    Acta Geographica Sinica    2020, 75 (8): 1603-1616.   DOI: 10.11821/dlxb202008004
    Abstract961)   HTML46)    PDF (3955KB)(445)      

    Border area is not only an important gateway for inland opening-up, but also an critical part in the building of a moderately prosperous society and optimizing national urban spatial pattern in China. Due to the location, natural resources endowment, and traffic accessibility, the urbanization development is relatively slow in border areas. Therefore, border area is a special area that should be given close attention, especially under the background of the Belt and Road Initiative and China's regional coordinated development program. Based on the county-level data from 2000 to 2015, this paper tries to analyze the spatio-temporal pattern of urbanization in 134 border counties, and applies the geographical detector method to study the driving forces of urbanization in border areas. Conclusions are as follows: (1) From 2000 to 2015, urbanization rate in border areas was lower than the national average, and the gap was widening. Some border counties in southern Xinjiang, Tibet, northeast of Inner Mongolia, and Yunnan, are even facing the problem of population loss. (2) In the same period, urbanization rate in the northwestern and southwestern borders is low, but it grows relatively fast compared with other border counties; urbanization rate in Tibetan border area is the lowest and grows relatively slowly; urbanization rate in the northeastern and northern border areas is slightly higher, but it grows slowly or even stagnates. (3) Transportation and industry are the important driving forces of urbanization in border areas, while the driving forces of market is relatively weak. And there are obvious mutual reinforcements among the driving forces, while the effort of resource force increases obviously after interaction. (4) Urbanization rate in the northwestern and southwestern border areas grows relatively fast, with industrial power and transportation power, market power and administrative power as the main driving forces. Tibetan border area has the lowest urbanization rate and growth rate, as the driving force of urbanization with strong contribution has not yet formed in Tibet. In the northeastern and northern border areas, the contribution of transportation power to urbanization is greater than that of other forces, and its interaction with market and industry has obvious effects on urbanization.

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    Spatio-temporal changes of cotton production in China from 1950 to 2015
    MA Chunyue, Mamat Sawut, YAO Jie, Gulnur Isak
    Acta Geographica Sinica    2020, 75 (8): 1699-1710.   DOI: 10.11821/dlxb202008010
    Abstract954)   HTML49)    PDF (4412KB)(465)      

    Based on the distribution data of cotton production in China from 1950 to 2015, the study aims to investigate the spatio-temporal changes and gravity center migration path in cotton production, area and yield in China by methods of time-series trend and spatial analysis. Then, contribution rates of cotton area and yield to the changes of cotton production are quantified. The results indicate that: (1) China's cotton production and yield showed an overall upward trend over the past 65 years. Among them, the production increased by 521.44×104 t and the yield increased by 1381.83 kg/hm2. After five periods of violent fluctuations, stable development, and three ups and downs, the cotton area was basically the same compared with the year 1950. (2) There was a large regional gap between cotton yield and cotton area, but the overall trend was increasing. The variation trend of cotton yield per unit area was stable, among which the annual fluctuation of cotton production in the inland cotton area of northwest China was the largest. (3) From 1950 to 2015, nearly 87% of China's cotton-growing regions increased their production, about 63% of the regions decreased cotton area, and more than 70% of the regions increased cotton yield. The production and yield of the three major cotton areas have increased, but the growth rate has been decreasing. The northwest inland cotton area had the smallest shrinkage, and it was also the main area for China's cotton area growth. (4) China's cotton production has formed a "southeast-northwest" pattern. The main production area has changed from the Yellow River basin to the northwest inland; the cotton production and area center of gravity have moved to the northwest, with a total moving distance of 1947 km and 1398 km, respectively. From 2010 to 2015, the moving speed was the highest, reaching 140 km/a and 159 km/a, respectively; the production center of cotton in the northwest inland area moved from Hotan to Aksu. The basin cotton area was moved from Lu'an to Huanggang, and the Yellow River basin cotton area was moved from Handan to Liaocheng. (5) The contribution of national cotton production has gradually changed from yield dominance to area dominance. From the perspective of cotton regions, cotton areas in the Yangtze and Yellow river basins have gradually changed from yield dominance to area dominance, and the northwest inland cotton areas have been driven by area.

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    Urban scaling law and its application
    GONG Jianya, XU Gang, JIAO Limin, QIN Kun
    Acta Geographica Sinica    2021, 76 (2): 251-260.   DOI: 10.11821/dlxb202102001
    Abstract924)   HTML1)    PDF (2438KB)(1)      

    The introduction of complexity science in urban geography has provided a new perspective to understand cities. Urban scaling law is one of the simple rules behind complex urban systems, which describes how urban indicators scale with urban population size within the system of cities. Social interaction-related urban indicators, such as GDP and innovation, super-linearly scale with urban population in a power law form, while infrastructure-related urban indicators, such as roads and gas stations, sub-linearly scale with population. Other urban indicators linearly scale with population, which are related to human individual needs, such as jobs and household electricity consumption. In this study, we first summarize the content and progress of urban scaling law during the past decade (2007-2020) from the following four aspects: the validation of urban scaling law, the explanation on the mechanism of urban scaling law, the application of urban scaling law, and the criticism of urban scaling law. We further compare the fundamental differences between the urban scaling law and urban allometric growth. Urban scaling law describes quantitative relationships between urban indicators and population size across cities, while urban allometric growth emphasizes the temporal growth of individual cities. Our analysis indicates that the cross-sectional urban scaling law cannot be applied to predict temporal trajectories of individual cities. Finally, we introduce the scale-adjusted metropolitan indicator (SAMI) for the evaluation of economic performance and urban land use efficiency in 291 Chinese cities, which is based on the theory of urban scaling law. The conventional evaluation of cities based on per capita indicators ignores the non-linear scaling relationship between urban indicators and population size. For example, the GDP per capita of large cities ranks high thanks to their advantages of population size. SAMI eliminates the influence of city size and can compare urban performance more objectively. Cities with higher SAMIs of GDP experience a higher efficiency in economic output (GDP) and they are concentrated in southeast coastal regions, middle reaches of the Yangtze River, and Xinjiang. On the contrary, cities in the northeastern China and Central China Plains experience a relatively low efficiency in economic output. Future studies are encouraged to focus on the mechanism of urban scaling law, the unified model for the evolving urban system across cities and over time, and the scaling law within cities.

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    Review and prospect of the 80th anniversary of Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences
    GE Quansheng, LIAO Xiaohan, GAO Xing, FENG Zhiming, LIU Weidong, LIAO Xiaoyong, ZHU Yunqiang
    Acta Geographica Sinica    2020, 75 (12): 2537-2546.   DOI: 10.11821/dlxb202012001
    Abstract849)   HTML85)    PDF (1099KB)(219)      

    The year 2020 marks the 80th anniversary of the establishment of Institute of Geographic Sciences and Natural Resources Research (IGSNRR), Chinese Academy of Sciences (CAS). Looking back over the past 80 years, the institute has experienced the initiation of Institute of Geography of China in Beibei, Chongqing in 1940, then the founding of Institute of Geography, CAS in 1953 and Commission for Integrated Survey of Natural Resources, CAS in 1956, and the final merger of the above two institutes into the IGSNRR in 1999. After the endeavour of three generations, IGSNRR innovates geography and resource sciences and has made contributions in different stages to the development of the country and the progress of human civilization. This paper commemorates the 80th anniversary of the IGSNRR by reviewing the development and progress of the institute over the past 80 years, summarizing the classic scientific research achievements and the major science and technology infrastructures, as well as looking forward to the future of IGSNRR.

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    Influencing mechanism of regional ageing in China based on the Structural Equation Model
    AO Rongjun, CHANG Liang
    Acta Geographica Sinica    2020, 75 (8): 1572-1584.   DOI: 10.11821/dlxb202008002
    Abstract833)   HTML44)    PDF (3139KB)(356)      

    Since the 1970s, great progress has been made in research on the spatio-temporal pattern of population ageing at multiple spatial scales by both domestic and foreign scholars. However, the analysis of the process mechanism of regional ageing is still insufficient. Based on the county-scale data in 2000 and 2010 censuses, the spatio-temporal pattern of population ageing is statistically analyzed. Moreover, the Structural Equation Model (or SEM) is developed to explore the path relationship between various variables. Consequently, the influencing mechanism of regional ageing process is thoroughly revealed. The main results are as follows. Firstly, the line from Baotou City of Inner Mongolia autonomous region to Tengchong County of Yunnan province (or BT Line) is a geographical demarcation of regional ageing disparities in China. Southeast of the BT Line witnesses contiguous areas of higher ageing counties which interspersed with lower ageing counties, whereas northwest of the BT Line is a continuous area of lower ageing counties with just one middle-level ageing belt located in the north margin. Secondly, the fitting results of SEM interpret the influencing mechanism of regional ageing disparities in China. Thirdly, life expectancy, fertility and migration are three endogenous factors of regional ageing process. Thereinto, life expectancy has significantly positive effect, while fertility and migration have significantly negative effects on regional ageing. Lastly, geographical environment has significant direct and indirect effects on regional ageing in China. In general, the income increase, social progress, and the improvement of living conditions and natural environmental quality would enhance regional ageing level, otherwise the improvement of urbanization level would decrease regional ageing level.

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    Tri-clustering: Construction and practice of space-time integrated analysis tool
    CHENG Changxiu, SONG Changqing, WU Xiaojing, SHEN Shi, GAO Peichao, YE Sijing
    Acta Geographica Sinica    2020, 75 (5): 904-916.   DOI: 10.11821/dlxb202005002
    Abstract829)   HTML31)    PDF (5193KB)(349)      

    With the improvement of geographic data acquisition capabilities, the volume of geographic data has been growing exponentially, and the data types as well as characteristics have become more diverse. The effective identification and classification of data has become the key to understand spatio-temporal patterns, evolutionary processes, and driving mechanisms of geographic phenomena. However, traditional clustering methods are facing some challenges, such as large amount, high-dimensionality and poor-quality of the data to be dealt with. Therefore, it is necessary to improve clustering methods. This paper first describes the transformation from one-way clustering to tri-clustering. One-way clustering methods perform the clustering analysis along with the samples or the attributes. They played an important role in previous studies, but ignored local features that are very similar. Co-clustering methods perform the submatrix partitioning scheme based on location similarity of elements within the data matrix. They avoid shortages of one-way clustering by realizing the clustering from both rows and columns, making similar elements into the same submatrix and dissimilar ones into different ones. However, they cannot satisfy multiple directions interpretations of geographical research since they do not support 3D panel data body. Then, we develop a new tri-clustering method, presents the workflow of using tri-clustering to spatio-temporal patterns' studies, and summarizes how to construct the 3D data matrix for clustering according to different aspects of 'space-time-scale-attribute' involved in the analysis. Finally, we show some practices of tri-cluster. The results show that: (1) Tri-clustering is an effective method to identify the spatio-temporal differentiation of geographic data in the era of big data by solving problems, i.e. data of high dimensionality and low quality. (2) Tri-clustering is universal in the algorithmic level when facing different geographic topics, but the differences rely on the 3D data matrices constructed according to different aspects of "space-time-scale-attribute" involved in the analysis. And, different data matrices are clustered to different results, which answer different topics. (3) Tri-clustering is able to interpret the spatio-temporal differentiation of geographic data in multiple directions, multiple scales, and multiple hierarchies, and thereby reveal the superposition effects of spatio-temporal scales of geographic features. Finally, we emphasize the significance of constructing 3D data matrices based on different geographic topics and expect that tri-clustering methods can enhance the ability to analyze geographic data with multiple spatial scales and attributes in the future.

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    Urban expansion and form changes along the Belt and Road Initiative
    HAI Kai, WANG Siyuan, MA Yuanxu, YANG Ruixia, TU Ping, LIANG Juanzhu, LIU Weihua, WU Linlin
    Acta Geographica Sinica    2020, 75 (10): 2092-2108.   DOI: 10.11821/dlxb202010005
    Abstract819)   HTML46)    PDF (10319KB)(568)      

    Although more and more people realize the important role of the urbanization process on the economic, political and environmental systems along the Belt and Road, the study on urban expansion and form changes is still limited. Based on the latest 300 m resolution global land cover dataset from 1992 to 2015 released by the ESA Climate Change Initiative project, DMSP/OLS night lighting data from 1992 to 2012, and LandScan population data from 2000 to 2015, in this paper we first analyzed the spatial pattern of urban land growth and dynamics in the ten major sub-regions along the Belt and Road from 1992 to 2015. Then, by analyzing the spatial and temporal changes of urban land density in concentric rings in 1992, 2003 and 2015, the expansion and form changes of 80 cities along the Belt and Road were quantified. Finally, the long-term relationships between urban land area, weighted lighting area and urban population were quantified by using three statistical models, including linear, power-law and exponential function models. The results show that the urban land area along the Belt and Road increased from 0.24% in 1992 to 0.56% in 2015, and developing countries in Africa and Asia are major contributors. The density of urban land in the concentric rings is decreasing from the city center to the urban fringe, and the spatial distribution between cities is completely different. Comparisons among cities in China, Europe, Africa, West Asia, Southeast Asia, and India with populations of more than one million, show that, in addition to the decentralization of China's urban form, the overall urban form of other sub-regions became compact. Further analysis results show that the urban economic vitality and urban population distribution trends will affect the urban spatial expansion and form changes at different levels.

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    Changes of the physical and human geographical environment in China during the past 2000 years
    GE Quansheng, ZHU Huiyi
    Acta Geographica Sinica    2021, 76 (1): 3-14.   DOI: 10.11821/dlxb202101001
    Abstract792)   HTML34)    PDF (1859KB)(206)      

    Understanding the changes of physical and human geographical environment during the past 2000 years in China is beneficial to establish the position, direction, focus areas, and initiatives of "Beautiful China" construction. In this paper, we integrated the results published in research papers, summarized the general characteristics of geographical environment changes in the history, and explored the implications of these changes on the construction of ecological civilization. The results implied that historical changes in China's land surface had been mainly manifested by the multi-scale quasi-periodic fluctuations and regional differentiation of climate, the fragmentation of the Loess Plateau, the expansion of desertified land in the northern regions, the gradual migration of delta coasts, the large scale shrinkage of lake systems especially in the Yellow River and the Yangtze River basins, and the decline in area of forests and the grasslands of northern China. Meanwhile, the economic and social changes were prominently reflected in the population growth and pattern changes, the migration of economic center to the southeast, the expansion of cultivated land to the periphery, and the transportation network evolution. From the above results, we could achieve the following enlightenments: in the future, the deserts in the northern region would still exist, and the lake systems in the middle and lower reaches of both the Yellow River and the Yangtze River were difficult to restore. The grain transportation from the south to the north disappeared in the history. But there was still much room for improvement in the coverage rate of forests, the transportation network could still achieve a higher level, and at the same time, we must mitigate the risk from climate change in the coastal cities.

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    Stages and spatial patterns of urban built-up land transition in China
    QU Shijin, HU Shougeng, LI Quanfeng
    Acta Geographica Sinica    2020, 75 (7): 1539-1553.   DOI: 10.11821/dlxb202007015
    Abstract791)   HTML48)    PDF (5230KB)(403)      

    Since the reform and opening-up in 1978, the morphology of urban built-up land (UBL) has been changed significantly due to the rapid socio-economic development in China. Moreover, this change shows an unbalanced variation over space. Based on the UBL area and census data from 1981 to 2015, we use the moving T-test, kernel density estimation and Gini coefficient to identify the abrupt change points over UBL transition process and present its dynamic spatial pattern. This research exhibits four main results. First, there are three identified stages over the transition process, namely, low expansion rate of UBL-decrease of per capita UBL (1981-2000), moderate expansion rate of UBL-slow increasing rate of per capita UBL(1990-2000) and high expansion rate of UBL-high increase of per capita UBL (2000-2015). Second, the spatial pattern of UBL area transition proceeds slowly over the periods of 1990-2000 and 2000-2015. Cities with a high expansion rate of UBL tend to present a spatial pattern of an agglomeration over the Yangtze River Delta and the Pearl River Delta, and the rest of the regions that tend to show a spatial pattern of an dispersion are provincial capitals in the central and western regions. On the contrary, cities with a high increasing rate of per capita UBL tend to originate from the eastern region to the entire country. Third, the variance of the UBL tends to be smaller during 1990-2000 and then greater during 2000-2015 over space, while the variance of the per capita UBL tends to be smaller during 1990-2000 and then stable during 2000-2015 over space. Lastly, we find that the results correspond to the previous theory of regional land use transition, and the socio-economic transformation phenomenon demonstrates the three identified stages. Moreover, the transition of spatial pattern reveals the fact that the change of national development strategy is from the priority of eastern coastal areas to the regional coordination. This work fills in a gap of quantifying the stage of land use transition, and provide support references to UBL management in the socio-economic transformation in the new era.

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    Impacts of climate and land use/cover changes on runoff in the Hanjiang River basin
    TIAN Jing, GUO Shenglian, LIU Dedi, CHEN Qihui, WANG Qiang, YIN Jiabo, WU Xushu, HE Shaokun
    Acta Geographica Sinica    2020, 75 (11): 2307-2318.   DOI: 10.11821/dlxb202011003
    Abstract789)   HTML27)    PDF (3823KB)(252)      

    As a link between the atmosphere and the geosphere, the hydrological cycle is affected by both climate change and Land Use/Cover Change (LUCC). However, most existing research on runoff response focused mainly on the impact of the projected climate variation, neglecting the influence of future LUCC variability. Therefore, the objective of this study is to examine the co-impacts of both projected climate change and LUCC on runoff generation. Firstly, the future climate scenarios under BCC-CSM1.1 and BNU-ESM are both downscaled and corrected by the Daily Bias Correction (DBC) model. Secondly, the LUCC scenarios are predicted based on the Cellular Automaton-Markov (CA-Markov) model. Finally, the Soil and Water Assessment Tool (SWAT) model is used to simulate the hydrological process under different combinations of climate and LUCC scenarios, with the attempt to quantitatively evaluate the impacts of climate change and LUCC on runoff generation. In this study, the Hanjiang River basin is used as the case study area. The results show that: (1) compared with the base period (1966-2005), the annual rainfall, daily maximum and minimum air temperatures during 2021-2060 will have an increase of 4.0%, 1.8 ℃, 1.6 ℃ in RCP4.5 scenario, respectively, while 3.7%, 2.5 ℃, 2.3 ℃ in RCP8.5 scenario, respectively. (2) During 2010-2050, the area proportions of forest land and construction land in the study area will increase by 2.8% and 1.2%, respectively, while those of farmland and grassland will decrease by 1.5% and 2.5%, respectively. (3) Compared with the single climate change or LUCC scenario, the variation range of future runoff under both climate and LUCC is the largest, and the influence of climate change on future runoff is significantly greater than that of LUCC. This study is helpful to maintain the future water resources planning and management of the Hanjiang River basin under future climate and LUCC scenarios.

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