From the policy allowing couples to have a second child if one parent is an only child to universal two-child policy, fertility policy in China had changed in succession, which had caused extensive social concerns and would have an influence on Chinese demographics in the future. This article projects the trend of total population and demographic structure in China after implementing the universal two-child policy by queue group element method from the demographic perspective, and analyzes the influence of the policy on Chinese population spatial distribution from a geographic perspective. The results show that: (1) Implementing a universal two-child policy can reduce the declining trend of the total population, aging of the population, and dropping of working age population. (2) Eastern China has the highest population density, followed by the central, northeastern, and western regions. Implementing a universal two-child policy can increase the population density of the area to the southeast of the Hu Line, but there will be little change to the northwest of the Hu Line. The current population spatial distribution pattern will continue to exist. (3) Based on the provincial-level annual change intensities of population density, China can be divided into rapid population growth zone, medium-speed population growth zone, slow population growth zone, and stable population zone.
Fine spatial scale population distribution has increasingly become a research hotspot yet a difficult question in the field of population geography. It has practical values in application and scientific significance for relevant research, such as disaster risk and impact assessment, resource allocation, and construction of smart cities. Residential building scale is considered an important part of fine spatial scales for population distribution. Research on the spatialization of population data at this scale has increasingly attracted academic attention. In this study, a population distribution vector data set at the residential building scale was established for six residential committees in Xuanzhou District, Anhui Province in 2015 based on residential space attribute data. Data used in the study include residential building patch area, percentage of housing area within residential building patches, building floor number, and public area rate. The method takes residential space attributes as variables for spatializing population data and treats residential building patches as population distribution location in geographical space with town boundary and town-level demographic data as controls. The spatialization method used in this study reveals detailed information about population distribution in urban areas. The results show that: (1) The population distribution data, obtained by using residential space attributes, are proved to be of high accuracy and reliability. The mean absolute relative error for 29 communities (villages) is less than 7%. The absolute relative error of 25 out of 29 communities (villages) is less than 10%. The proportion of patches whose estimated number of people is in reasonable range is higher than 74% in a total of 1102 residential building patches. The proportion of patches whose relative error is in slightly underestimated area (-10%, 0) and overestimated area (0, 10%) is higher than 9%. (2) Building volume , defined by residential building patch area and building floor number, is a key factor to estimate accurately the number of people within a residential building. The percentage of housing area can further improve model accuracy. Public area rate plays an important role to increase estimated number of people in underestimated area and decrease that in overestimated area, but is too weak to adjust the estimated number of people to reasonable range. In conclusion, spatialization based on residential space attributes can be an important method for population spatialization research at the residential building scale.
The study of rural economic development in the Yellow River Basin has an important theoretical and practical significance to revealing the driving mechanism of rural economic differentiation and realizing rapid development of rural areas in the Yellow River Basin. This article developed a comprehensive evaluation index of economic development level by using Analytical Hierarchy Process (AHP). It applied GIS, GeoDA software and combined ESDA-GIS spatial analysis framework to analyze the spatial and temporal differences of rural economy of 332 counties in the Yellow River Basin from 1990 to 2013. The findings show that: (1) The level of rural economic development in the eastern region of the Yellow River Basin was higher than the west. The overall level has gradually increased in the past 20 years. The highest and higher level zones were mainly distributed in the lower Yellow River reach and clustered; the medium level areas were mainly located in the traditional agricultural and pastoral areas of the Yellow River Basin, and the lowest and lower zones were located in the source region and their surrounding areas of the Yellow River. The spatial pattern showed that the high development level area was located in the center and there was a decreasing trend from the center to the surrounding areas. There was also clear spatial stratification among the different development levels; (2) The degree of spatial agglomeration was increasing since 1990. Moreover, areas of significantly high-high and significantly low-low development were dominant, showed a stable distribution, and concentrated in the downstream and upstream areas of the Yellow River respectively. On the other hand, areas of high-low and low-high development did not show a stable distribution and were fewer in number. (3) Factors including location, industrial structure, and development policy were the main causes of the differentiation of rural economy in the Yellow River Basin.
Using weighted mean travel time model, gravity model, principal component analysis, geostatistical analyst, exploratory spatial data analysis, and correlation and regression analysis methods and techniques, this study conducted an in-depth analysis of accessibility and urban spatial connections of 107 county-level administrative units in Shanxi Province. The results are as follows. First, accessibility of cities in Shanxi Province is highest in the highly urbanized area of the Taiyuan Basin and gradually decreases outward, which presents a core-periphery distribution pattern. Locally, accessibility in the eastern part is better than the west, and the south is better than the north. Second, economic connections at the county scale form an one core, one circle, and three groups spatial pattern; the overall linkages of cities differ and show a provincial capital and cities with higher overall strength centric distribution pattern. Peripheral county-level units along the Yellow River in the west present weak connections with other units and the overall linkages are small too. Cities in Shanxi Province have close connections with Beijing, Shijiazhuang, Xi'an, Ji'nan, and Zhengzhou and have weak connections with Yinchuan, Lanzhou, and other western provincial capital cities. Third, economic strength, transportation condition, location, urbanization level, and relief of land surface are the main influencing factors of economic connections at the county scale in Shanxi Province.
With urbanization and the decrease of rural population, a large number of rural schools in China has been merged. How to optimize the layout of schools has become a research hotspot. In 2008, China issued the standards of school size, but the impact of the standards on the layout of schools is yet to be researched. In this study, based on existing location allocation models, constraints of the size of schools were applied to build a model of school layout optimization, which also considered the constraint of maximum distance to school. We chose the primary schools in Yanqing District, Beijing for case study and used the branch and bound algorithm and global optimal solution method to solve the model. The data range from 1995 to 2010, which include 295 primary schools distributed in nearly all villages at the start, and 46 primary schools after the large-scale school merging. The results show that after the school size constraints were applied in the optimization model, 65.22% of the rural schools need to be relocated, which reflects the significant impact of school size constraints. But school spatial distribution pattern remained essentially unchanged at the town and township scale, with the proximity index higher than 1, larger than before. After applying the size constraints, the distribution pattern of schools was still a discrete type. But the degree of dispersion has decreased. The optimal solution with school size constraints can satisfy the national standards. At the same time, the optimal solution results in an increase of schooling distance at 135 m per student, which is acceptable. Finally, this study examined the implications of the results for the school layout optimization policy.
Classification based regionalization is an effective way to analyze geographical national conditions and a basis for studying the regional differences in the classification characteristics, combinations, change, and spatial differentiation of geographical national conditions. The index system of the classification-based regionalization of geographical national conditions is determined through the analysis of the basic statistical data of the geographical national conditions survey. Using multidimensional scaling and cluster analysis, the classification-based regionalization model of geographical national conditions was established. The classification-based regionalization experiment was carried out using the geographical national conditions survey data of Henan Province. The number of regions of geographical national conditions was initially intuitively determined through multidimensional scaling on geographic national conditions data of Henan Province. On this basis, the classification-based regionalization was achieved by K-means clustering. The type of regions is defined and explained according to the cluster centers and the characteristics of index data in each cluster. Finally, the clustering result is spatialized. The experimental results show that the geographical national conditions in Henan province can be divided into four regions: extreme value region, low value region, median value region and high value region. The spatial agglomeration effect of regions of geographical national conditions in Henan Province is significant, and It is mutual tolerance and penetration between each classification-based regionalization and constructed of four southwest to northeast strip. In the overall planning of regional development and realizing regional coordinated and sustainable development, we can make feasible regional balanced development policies according to the geographical national conditions of each region.
Technological progress and institutional change are key drivers for industrial development. The rapid development of information and communication technology has weakened the demand of industrial production for local resources and promoted the free flow of capital, knowledge, labor, and other factors of production in a wider area. The "temporal and spatial compression" formed by technological evolution has further changed the pattern of global interests and led to institutional reform aimed at regional integration and trade liberalization. This loosens the restriction of trade costs on location options for productive activities and provides more possibilities for cross-regional production linkages and the establishment of global production network (GPN). With the formation of GPN, transnational enterprises (TNE) tend to locate in regions with cheaper labor cost, more preferential policies, and greater market potential in order to optimize their cost-benefit of operation on a global scale by means of foreign direct investment (FDI). Under this trend, developing countries become essential destinations for FDI, which in return makes FDI a key factor that affects the industrial change of host countries through spillover and competition effects, for example. Technological proximity between foreign and domestic parts in one industry also contributes to enhancing or weakening the effects of spillover and competition, then influences the interaction between the spatial dynamics of foreign direct investment and domestic industrial change, and further exerts impacts on regional economic growth. Based on the theories of global production network and Evolutionary Economic Geography and using four-digit manufacturing data of China's prefectural-level cities in ASIFs from 1998 to 2008, this study analyzed the interaction between FDI spatial dynamics (including FDI enterprise entry and FDI enterprises exit) and domestic industrial change and the impact of technological proximity on FDI spatial dynamics and domestic industrial change by using qualitative and quantitative analysis methods. The results show that the entry and exit of TNEs both induced change of domestic industries, while the spatial dynamics of FDI demonstrated the most significant effect in central and western China, followed by eastern cities. FDI entry contributed more in promoting domestic industrial change than FDI exit in the Northeastern. Technological proximity between domestic industries and FDI industries mostly weakened the positive effect of different spatial dynamics of FDI on domestic industrial change, except for the entry of FDI during 1998-2003. From a regional perspective, technological proximity in eastern cities showed positive effect on both entry and exit of FDI, suggesting a typical example of "strategic coupling." On the other hand, in middle, western and northeastern cities, higher technological relatedness has become an essential reason that prevents FDI from promoting the development of domestic industries.
High-speed rail as the infrastructure for material and information exchange is important channels in urban agglomerations that connect urban centers and facilitate urban expansion, and urban agglomeration is a greater metropolitan area whose internal separation is reduced by high-speed rail system. This study used passenger flow data of 380 sites in the Yangtze River Delta high-speed railway system to construct a 20 by 20 matrix for examining connections between cities in the Yangtze River Delta Urban Agglomeration and its spatial structure. The results show that: (1) The density of network connection between the core cities in the Yangtze River Delta—Shanghai, Nanjing, Hangzhou, and Ningbo—is higher than between other cities; (2) Connections between the core cities of the Yangtze River Delta and cities along major transportation axes, such as Shanghai to Zhenjiang and Jiaxing, Nanjing to Danyang and Huzhou, and Suzhou to Changzhou and Kunshan, have been strong; (3) In terms of "spatial flow" stratification, the first level city network mainly consists of Shanghai-Suzhou-Wuxi-Changzhou and cites along the transportation routes between these cities; the second level city network is mainly composed of Shanghai and Ningbo and cities along the route; the third level city network is mainly composed of Shanghai-Hangzhou-Ningbo and cities along the transportation routes between them; the fourth level city network is mainly composed of Shanghai Jinhua and Yiwu and cities along the route.
Chinese traditional villages provide the environment where humans live in harmony with nature for thousands of years. They record traditional architectural, folk custom, and residential forms. With the accelerating process of urbanization, the very existence and sustainable development of traditional villages have faced great challenges. To facilitate better protection and utilization of traditional villages, it is particularly important to study them through multiple perspectives. In addition to specific protection measures at the micro-level, we should also strengthen the study of traditional village spatial distribution at the macro-level. Geographic grid is a basic method to express complex geographic phenomena, analyze natural and social data, and simulate the function and behavior of geographic systems. This study extracted the coordinates of villages from Baidu map and remote sensing images for the village location point data. Combined with geographic grid classification method, it analyzed the spatial distribution patterns of the three published batches of traditional villages (total 2555), and found that these villages are mainly distributed in southeastern China: 586 and 781 villages were found in the first-level grids 18 and 19, accounting for 96.6% of these traditional villages. By analyzing the discreteness of village distribution in the second-level and third-level grids, structure of the spatial distribution of these villages became clearer, and this provides the framework and foundation for constructing a traditional village database.
With accurate dating, high resolution, and high continuity, tree-ring data become one of the important sources for reconstructing the climate change. The sampling sites distribute widely, many tree species were selected, and the chronologies are very long for studying the relationship of the tree ring and dry-wet changes in China. Significant progress has been made in analyzing the response of tree radial growth to dry-wet changes and reconstructing historical dry-wet climate change based on various research proxies, such as tree-ring width, density, and stable isotopes. In general, moisture condition, especially in the spring and autumn and annual humidity are the important influencing factors of tree-radial growth in low altitudes of arid and semi-arid areas. For trees in the upper limit of forest vegetation, relatively cold-wet areas, and the subtropical climate zone in China, the correlation between tree growth and precipitation was weak. Dry-wet climate reconstruction based on tree-ring data in China is plentiful. Up to now, many precipitation series of more than 1000a or even over 2000a were reconstructed in a large number of regions. The longest tree-ring chronology is 4500a, and the longest precipitation reconstruction sequence is 3500a. The brief summary of selected tree-ring results in this article will provide references and help for tree-ring sampling and dry-wet climate reconstruction.
Storm surges are a phenomenon of abnormal water-level rises under the influence of strong atmospheric turbulence in coastal areas and are effected by many factors, such as sea-level rise. China has seen frequent storm surges, especially in the southeastern coastal areas where their frequency is high and disaster losses are serious. This article systematically summarized the progress and main problems of storm surge research in China with regard to the hazard, vulnerability, and risk regionalization. Based on the characteristics and risk assessment of storm surges, the impact of climate change and adaptation strategies were further investigated. Especially in the context of climate change, future trend, recurrence periods, and high risk areas of storm surges would be greatly affected by sea-level rise. Thereby, a comprehensive risk assessment incorporating factors such as sea-level rise is urgently needed. Moreover, the changes in natural conditions and socioeconomic development in the coastal areas under global climate change should be taken into account to improve risk assessment with the combination of short-term and long-term views. In order to adapt to the risk of storm surge disasters under climate change, China has continuously improved the capacity building for emergency preparedness, structural defense, and policies and regulations to improve the ability of disaster prevention and mitigation.
Professor Shen Yuchang, as a pioneer and founder of modern river geomorphology research in China and his original idea created a new era of experimental research of fluvial geomorphology. The author wrote this article to celebrate the 100th anniversary of the birth of Professor Shen. The article introduces the following developments: (1) A vision for river geomorphological experiments and preparing for building the fluvial geomorphic laboratory, including Prof. Shen's original idea, research and preparation for the laboratory, test operation and starting experiments. (2) Expansion of the fluvial geomorphological laboratory and booming experimental research, including a series of experimental research ranging from major national research projects and local projects, pioneering experimental research on the evolution of watershed geomorphic systems and slope systems, and establishing the process-response similarity theory for fluvial geomorphological experiments. (3) Recent progress in river geomorphological experiments, including the development of the river geomorphological laboratory and updating lab equipment, phylogenetic evolution experiment of channel patterns, and river geomorphic system's response to dome and depression of non-uniform uplift and subsidence, among others. (4) Finally, the article points out that in order to advance the study on fluvial geomorphological experiments in China, it is needed to continue innovations in six areas, including strengthen the experiments on non-steady state river geomorphological process caused by tectonic movement, climate change, and rapidly changing human activities to reveal the complexity, sensitivity, and precursory characteristics; and strengthen collaboration and integration of experimental research forces to enhance comprehensiveness of research and cross fertilization.
