The history of human activities on the Tibetan Plateau is crucial for understanding human adaptation to the extreme environment of cold and hypoxia. This paper systematically reviews the archaeological discoveries and studies in recent years, and provides an overview of five development stages of prehistoric human colonization of the Tibetan Plateau from the known of the earliest occupation until permanent settlement. 1) The Denisovan mandible and mitochondrial deoxyribonucleic acid (mtDNA) found in Baishiya Karst Cave (BKC), 3 280 m above sea level ( a.s.l.), on the northeastern Tibetan Plateau, indicate that the ArchaicHomo sapiens, such as Xiahe Denisovan, may have adapted to the plateau at least 190 thousand years ago (ka) during the late Middle Pleistocene and long-term existed in and around the BKC until the last Glacial period; 2) The Initial Upper Paleolithic assemblages, from excavations at Nwya Devu site (4 600 m a.s.l.), reveal that modern humans began to explore the interior region of the Tibetan Plateau as early as 40-30 ka; 3) The relatively rich microlithic sites on the plateau from last deglaciation to early-mid Holocene, show the frequent activities of microlithic hunt-gatherers during this period, especially during 0.9-0.6 ka, perhaps the results of climate warming; 4) According to the evidence of plant remains from the Neolithic sites, millet farmers have entered low-elevation regions (< 2 500 m a.s.l.) on eastern Tibetan Plateau at least 5.2 ka, and permanently settled in regions at elevation above 3 000 m a.s.l. on eastern Tibetan Plateau since 4.8 ka; 5) After 3.5 ka, the introduction and development of wheat and pastoral economy facilitated permanent human occupation in the high-altitude regions (> 3000 m a.s.l.) of the Tibetan Plateau, which is a consequence of cultural exchange in prehistoric Eurasia. These reflect the long-term physiological and cultural adaptation of prehistoric humans in the process of spreading and settling on the plateau. However, our understanding of prehistoric human activities on the plateau is still limited by the number of archaeological sites and excavated materials. Therefore, we suggest that future work should be focused on seeking more prehistoric sites, conducting the systematic study, and solving the following issues: the spatial and temporal distribution of prehistoric hunter-gatherers, farmers and herders on the plateau, their biological and behavioural adaptation to high-altitude environment and connection with prehistoric low-altitude population and modern Tibetans, and the formation and universality of alpine civilization. We expect that new discoveries and multidisciplinary endeavours will promote the understanding of these issues in the future.
Geographical Science is an important support for improving human understanding of the earth surface, exploring the relationship between man and land, and solving complex problems in resources, environment, development, and disasters. It is the mission and duty of the National Natural Science Foundation of China (NSFC) to lead scientific development and support the construction and cultivation of talent teams in all fields. Tracking the frontiers in the field of geographical science, optimizing the discipline layout and conducting strategic guidance are important tasks of the geographical science division of the NSFC. In this study, taking 4 479 applications in the field of geographical science of the NSFC in 2021 as samples, the word cloud analysis method was used to analyze the research hotspots of geographic science and various sub-disciplines. The results show that ‘deep learning’‘climate change’ ‘ecosystem services’‘hyperspectral remote sensing’‘Qinghai-Tibet Plateau’, and “sustainable development” are the hotspots of the research contents and methods of geographical science. In terms of intercross and fusion between sub-disciplines, the intercross of research hotspots between information geography and human geography is relatively weak, and the main common keywords are ‘spatial analysis model’ ‘geographic information system’ ‘remote sensing’, and ‘machine learning’. Hot keywords of Physical Geography and Human Geography are highly cross-integrated, and the hot common keywords include ‘ecosystem services’‘land use’‘land use change’‘sustainable development’ and ‘scenario analysis’. In the future, the NSFC-Division of Geography will start with keywords setting and interdisciplinary integration in order to further optimize the layout of Geographical Science from the strategic level, guide scientists to focus on frontier issues in Geography, and serve major national strategies such as carbon neutrality and rural revitalization.
Human activities have become a forceful geological agent on the Planet by rapidly and dramatically altering the natural world, which, in turn, is affecting the well-being of humans themselves. The cumulative impact of human activities on the Planet has driven an ever-evolving human-land relationship and left recognizable marks on the Planet’s surface, i.e., the human critical area (HCA), which is an area that characterizes the surface landscape created by human beings in the Anthropocene. It is a relatively homogeneous area of human activities within the geosphere and the basic unit of the human-land coupling system. Human’s perception of the human-land relationship over its nearly 10 000 years of history can be divided into 3 layers: human civilization and the earth’s environment; human activity and the geographical environment; and spatial behavior and land use. As the imprint mainly dominated by human activities on the earth’s surface, the HCA has a temporal-spatial attribute, showing in global, national, regional, local, and community scales. Each scale is with its types, structures, and expression forms. Specifically, the HCA on the global scale can be classified into the built-up area, agricultural area, ecological area, and bare area; the HCA on the national scale can be divided into the elemental area, functional area, and administrative area; the HCA on the regional scale can be classified into the ecological area, economic area, poverty area, and urban area; the HCA on the local scale can be divided into the small city, town, and village; the community-scale HCA can be classified into the block, residential building, and other geographical units. Further discussion on the HCA should focus on the followings: 1) identification, demarcating an objective spatial area that reflects the results of interactions of human-land through the analysis of factors (e.g., land use, transportation network, population density, economic level, night light, etc.) or the applications of deep learning and big data with the development of geospatial technology; 2) material cycle and energy flow, exploring the material circulation and energy flow in different types and scales in this key interface; 3) coupling mechanism and dynamics, exploring the rules and principles of element coupling, interface coupling, space-time coupling, scale coupling, system coupling, etc., as well as understanding the processes and manifestations of diverse dynamics over the evolved period of human to achieve coordination among subsystems; 4) geo-simulator and regulatory decision making, comprehensively simulating, analyzing, predicting, and optimizing the human key area with virtual simulation experiments. The HCA can provide an innovative theoretical and practical path for global sustainable development in the geoscience of China.
The conflicts between village scenic development enterprises and communities have always been a common concern in academic research and industry practice. As an effective theory for understanding the relationship between organizations, the resource dependence theory provides a new perspective to analyze the relationship between village scenic development enterprises and communities. This article integrates the 4 dimensions of the relationship among village scenic development enterprises and the communities, interests, power, and the degree of resource dependence into the resource interdependence analysis framework, using the Mengjinglai scenic area in Xishuangbanna as a case study. The primary data are collected through interviews and observation. This article analyzes the dynamic evolution and the logic behind the evolution of the relationship between village scenic development enterprises and the communities. The study demonstrates that the dynamic evolution of the relationship between village scenic development enterprises and communities is the result of the change in the degree of resource interdependence between the two. In the initial stage of scenic area development, the dependence of village scenic development enterprises on the communities is less than that of the communities on the enterprises. In the game of interests between the two, the power of village scenic development enterprises is larger than that of communities, but the benefits obtained by the communities are continuously increased from zero. There is less contradiction between the two. In the mature stage of scenic area development, the dependence of village scenic development enterprises on communities is larger than that of the communities on the enterprises. In the game of interests between the two, the communities have more power than the enterprises. At this point, if the existing benefit distribution mechanism remains unchanged, it will have conflicts in interest distribution. This paper also inferred that with interventions and coordination from the government, the village scenic development enterprises will give way to communities when there is conflict of interests. This study provides a practical guiding significance for the scenic development enterprises which invest a village scenic area.
Up to now, the understanding of “geopolitik” and the discipline of geopolitics remains highly controversial. The development of critical geopolitics fails to dispel this misunderstanding and enhance the social influence of geopolitics. It is a deep-rooted misunderstanding to regard geopolitics simply as the influence of geographical environment on politics and to equate the geographical environment with the physical geographical environment. By systematically sorting out the development and evolution of the geopolitics, this paper considers “geopolitik” as the unique perspective, and multi-factor, cross-domain and cross-scale comprehensive analysis on international politics or international order, while geopolitics refers to the collection of its unique perspective and the comprehensive analytical methods, and the theories based on the perspective and methods. This unique perspective is mainly embodied in the analysis of the optimal combination of physical and human elements within the space at the national level, the comparison and correlation analysis at the system level and the cross-field and cross-scale interaction. The research methods mainly include the spatio-temporal analysis, historical analysis and system analysis. However, geopolitics as a whole is a poorly developed discipline, not because its thoughts are not deep enough, but because its analytical methods and techniques cannot meet the demands of complex realities, which meanwhile provides an excellent opportunity for the real study of China’s geopolitics. Chinese scholars should not only become the followers and promoters of western geopolitical theories, but also strive to be the contributors of original theories and methods. This may be the fundamental reason for establishing the theory and method of the geo-setting analysis as the main research direction in the revival of geopolitical research in China.
In the face of the dilemma that international R & D investment in the host country can no longer be infinitely divided, this paper incorporates the network location factors that determine the capacity of host country’s destination cities from point to into the framework of factors that affect the location determination of multinational corporations’ international R & D investment in a country. The empirical study finds that the traditional supply and demand factors based on a single regional perspective, such as FDI and R & D investment, can not well reflect the location selection pattern of multinational companies’ international R & D investment in China. The location choice of multinational R & D investment in China is not determined by an isolated ‘point’ factor in China’s destination city, but by the ‘surface’ factor that can be driven by the destination city. Therefore, the research on the location determination of international R & D investment in China can no longer be based on the traditional ‘point’ to ‘point’ perspective. The absolute dominant position of Beijing and Shanghai in China’s international R & D investment is mainly related to their absolute core position in China’s urban transportation, innovation and other networks. These findings contribute to the literature of location determination of international R & D investment of MNCs, and even to the study of location determination in a broader sense. Meanwhile, these findings have some certain significance on China’s investment policy.
This article studies the urban ecological efficiency of the Yellow River Basin, and discusses the spatial-temporal evolution characteristics of urban ecological efficiency and the threshold effect in the Yellow River Basin from 2003 to 2017 based on the perspective of unexpected output. The results showed that: 1) The ecological efficiency of the Yellow River Basin cities increased steadily, but the whole region and resource-based cities showed a certain gradient effect, with polarization phenomenon. 2) The ecological efficiency of each city is higher in the east and lower in the west, higher in the south and lower in the north, and there is a significant spatial spillover effect. 3) Resource endowment has a significant threshold effect. For resource-based cities, the relationship between producer services agglomeration and ecological efficiency is U-shaped, manufacturing agglomeration will have inhibitory effect after crossing the threshold, and industrial collaborative agglomeration always has a positive effect. For non resource-based cities, resource endowment will weaken the promoting effect of producer services agglomeration, while the influence of manufacturing agglomeration and industrial collaborative agglomeration is not significant after crossing the threshold.
Nowadays, subway has become an important component of daily travel for most megacity residents especially in commuting. Most of existing researches mainly attach importance to spatial accessibility by subway infrastructure network, while measuring accessibility based on timetable and organizational network allows accessibility research to expand to spatial-temporal dimensionality compared with only spatial dimensionality as delicacy of urban management and rising demand of travel timing by residents, which contributes to understand the relationship among travel behavior, subway network and urban space. The paper constructs organizational network of Beijing subway based on timetables of 340 stations, then applies method of network construction and cumulative opportunity accessibility method to make analysis and comparison on accessibility dynamics at station scale on spatial-temporal constraint of weekdays, weekends, peak hours and off-peak hours. The results show significant differences compared with results of subway infrastructure network: 1) For subway lines, organizations differ in different lines due to location of stations and land use function variations along lines. 2) Subway accessibility based on organizational network changes with the time of a day, the highest of which is at peak hours, and accessibility on weekends is slightly lower than that on weekdays; 3) There are spatial differences between subway accessibility based on organizational network and infrastructure network, the highest of which is at stations with 15-20 km distance from city center on weekdays and weekends, which is caused by subway network structure. To sum up, research on spatial-temporal accessibility is conductive for understanding delicacy management of subway network, and probing into urban spatial structure as well as travel pattern of residents.
Although China’s high-speed rail (HSR) construction started late, its development has been fast. After about two decades of construction, China has developed the HSR with the longest operating range, largest carrying capacity and largest geographical coverage in the world. As a new mode of transportation, HSR networks are valued as essential assets for facilitating the goods and factor mobilities including human resources, natural resources, technology, knowledge, and information. That means it will enhance the connectivity between cities, reduce regional economic inequalities and contribute to the achievement of territorial cohesion goals. This paper researches the impact of high-speed rail connection on the regional convergence in China (not including the data of Hong Kong, Macao and Taiwan). Regional export productive structure can reflect productivity differences. In this sense, upgrading of productive structure leads to economic upgrading. Based on the city-level panel data of Chinese Customs Trade Statistics (CCTS), the paper first calculates the cosine similarity of the export product structure between cities during 2008-2015, and then uses the difference-in-differences method to investigate the effect of HSR connection. Besides, It also provides insight into the heterogeneous effects of the HSR’s connection regarding the geographic distance, structure system and locations of city pairs. Results indicate that: 1) Cities’ export product structures tend to be much similar after connected by HSR in China, implying the positive contribution of HSR connections to the territorial cohesion and regional industrial upgrading. 2) The spatial heterogeneity of the impact of HSR on the similarity of regional export product structure is significant. Heterogeneous analysis suggests city pairs with medium distance, within and outside the city clusters, or between the east and west of China are becoming much similar in export product structure by HSR’s connection. While the export product structural similarity between eastern cities decreases significantly after the opening of high-speed rail. This paper explores the reconfiguration effect of China’s HSR on intercity connection and several policy implications can be drawn from these empirical findings. One policy implication of this paper is that investing in transport infrastructures seems to be a sensible and forward-looking strategy for China. Therefore, Chinese goverment should encourage more investment in HSR network construction in the future to enhance the spatial economic linkages between cities and the additional spillover effects in economic development. Another innovative policy lesson drawn from this issue is that not all city pairs could benefit equally from HSR connections. Chinese governments are expected to establish differentiated strategies to find a balance of growth and equity. It is beneficial to promote HSR construction between eastern and western cities to diffuse spillover effects to the lagging place. Besides, this study also provides an alert that local officials at peripheral areas should improve local infrastructure and be ready to undertake industrial transfer from connected regions, rather than just count on connecting to HSR to boost the local economy.
In this article, the average nearest neighbor and kernel density method are used to analyze the spatial layout of beautiful leisure villages. Besides, the entropy weighting method, geographic detector, and neighborhood analysis are employed to explore its influencing factors. The results show that: 1) On the national scale, the beautiful leisure villages are unevenly distributed in space, and the overall distribution is concentrated, forming the spatial characteristics of ‘two poles and multi-core’. 2) On the provincial scale, the density of beautiful leisure villages in the eastern coastal provinces is relatively high while the density in the high-latitude and high-altitude provinces of the western part is relatively low. With the exception of Qinghai and Tibet, the distribution of beautiful and leisure villages in various provinces presents small differences; the degree of agglomeration is low and tends to be evenly distributed. The beautiful leisure villages in Beijing and Tianjin have the best development in space. 3) Beautiful leisure villages are significantly influenced by human factors, such as rural basic conditions, tourism investment level, tourism market scale and national cultural resources. Its natural distribution tends to be in the warm and humid climate areas with the altitude lower than 200 m, near third-level rivers, excellent environmental quality, and close to cities or scenic spots with annual accumulated temperature higher than 3 400℃ or precipitation higher than 400 mm.
Urban amenity has an important impact on urban innovation and development, but there is a lack of research on the impact of metropolitan internal amenity and differences on urban innovation ability. Taking Beijing as the research area, this article uses coupling coordination degree model and multiple linear regression models to analyze the relationship between urban amenity and innovation ability. The main conclusions of this article are as follows. 1) The overall level of urban amenity distribution of Beijing gradually decreases with the increase of the distance from the central urban area to suburbs. 2) The northwestern districts in Beijing has better ecological environment amenity than the southeastern districts. However, artificial environment and social atmosphere decrease from the urban center to the surrounding areas and the urban amenity level of each district shows a phenomenon of agglomeration in spatial distribution, with high-high clustering concentrated in Dongcheng District, Xicheng District, Chaoyang District, Haidian District and Fengtai District and forming a “high urban amenity” area in Beijing. 3) Based on the coupling coordination degree model, it is found that except Pinggu District, Miyun District and Yanqing District, other urban areas in Beijing are in the high-level coupling stage. Haidian District, Dongcheng District, Xicheng District, Chaoyang District and Fengtai District have a high degree of coupling and coordination of innovation ability and amenity development, but there is also a lag between the development of urban amenity and urban innovation in all districts of Beijing. 4) There is a positive correlation between urban amenity and innovation ability in Beijing, but different urban amenity factors have different effects on innovation ability. Cultural and educational amenity has the greatest impact on urban innovation ability, and traffic amenity and social atmosphere have the second effect on innovation ability. The policy implication of this paper is that Beijing should promote the relative balanced development of artificial amenity level such as culture, education and traffic amenity to improve the coordination of urban amenity to enhance urban innovation ability of each district.
Since the reform and opening-up, cross-regional population mobility has reshaped China’s urban-rural relations and social structures, which enhancing the urban identity, sense of belonging and satisfaction of the migrants have become an important issue for deepening reform and sustainable urbanization. Based on the 2017 China Migrants Dynamic Survey, this study construct a multi-index evaluation system, and using GIS spatial analysis methods which analyzes the regional differences and spatial pattern. Beside, this study discusses the influencing factors of migrants’ psychological integration in 292 prefecture-and provincial-level cities of China. The results show that: 1) In the process of urbanization, the psychological integration index of the urban migrants in China is at a relatively high level, which the Chinese migrants has a positive willingness to integrate and a good experience of integration. 2) There are significant regional differences in the psychological integration of the migrants in China, which is inconsistent with the macro-social and economic development pattern. The level of the migrants’ psychological integration in the eastern coastal areas and a few far-western cities is lower than the national average level, which the northeast China, Shandong Peninsula, and Sichuan-Chongqing Urban Agglomeration is higher than the national average level. Meanwhile, the level of migrants’ psychological integration in far-western cities are also at a relatively low level, such as Tibet and Shaanxi-Gansu-Ningxia Urban Agglomeration. 3) There is a spatial agglomeration effect on the migrants’ psychological integration. The hot spots are concentrated in northern China ,which except for Sichuan-Chongqing Area. The cold spots are located in the southeast coastal areas of China, which presents a characteristic of north-south differentiation. 4) The migrants’ psychological integration is affected by multiple factors. With owner housing, employer employment status, and higher education level play an important role in promoting their psychological integration. However, the increase in wage income is not conducive to the process of psychological integration, which is related to the relative deprivation. There are differences in the household registration system and welfare arrangements between the outflow place and inflow place. To be specific, the migrants participating in the New Rural Cooperative Medical System in outflow place has a negative restraint effect on the psychological integration. Migrants with temporary residence card or residence card, while migrants with easier access to the urban public services are the main ways to achieve psychological integration. Furthermore, the speed of urban economic development is conducive to the migrants’ psychological integration. Finally, migrants with inter-provincial mobility have a negative effect. However, the economic development level, family scale and local residence time of the inflow place are not significant in the regression model.
Taking Yiwu Tea Competition festival as a research case, with the guidance of scaling theory, this article deeply analyzes the development process of Yiwu Tea Competition Festival and illustrates different actions and practices of multiple social subjects that promote its development and evolution through participatory observation and semi-structured interview method. The results show that: 1) There are two ways of scaling in the evolution of Yiwu Tea Competition Festival: One is to meet the market segmentation of Pu’er tea by using scaling-down, the other is to meet the local development needs by using scaling-up. 2) The scaling of the Yiwu Tea Competition Festival is driven by the promotion of the government, the support of tea enterprises, the cooperation of tea farmers and the pursuit of tea customers. 3) In the process of promoting the scaling of Yiwu Tea Competition Festival, the actions of multiple subjects met the interest demands of their respective groups, and the local government realized the local development relying on the tea economy. This article makes an in-depth analysis of Chinese tea culture from the perspective of 'festival and special events', and provides theoretical basis and case reference for tea villages to achieve development through local festival activities.
Due to the increase of global population and economic development, the water body inside of the cities and its surroundings has been continuously occupied since the 1970s, causing serious damage to ecological environment. Thus, it is very important to estimate the condition of water body occupied by urban land expansion around the world. With the data processing and analysis functions of the Google Earth Engine cloud platform (GEE), we explored the temporal and spatial characteristics of permanent and seasonal water body occupied by global urban land expansion from 1986 to 2015 using the dataset of global annual urban dynamics (GAUD) and global surface water (GSW). Our objective can be characterized by: 1) Describing the spatial distribution pattern of water body occupied by urban land expansion on a global scale; 2) Analyzing the characteristics of changes in the water area occupied by urban land expansion over time on global, continental, and national scales; 3) Discussing the potential ecological effects of water body occupied by urban land expansion and the suggestions to solve this problem in China. We find that water areas occupied by global urban land expansion increase firstly but decrease then, representing 1033.2 km2 over 30 years, in which the seasonal water body is 711.7 km2 and the permanent water body is 321.5 km2. Asia is the most significant continent with urban land expansion among the six continents, followed by North America and Europe, which accounts for 799.4 km2, 122.5 km2 and 61.1 km2 respectively. Meanwhile, Europe is the only continent which mainly dominates by permanent water body while Russia and Algeria are the counties dominating by that. Especially, China, the United States and India are the countries with the most serious water body occupied by urban land expansion, amounting to 573.1 km2, 109.6 km2 and 24 km2 respectively. Many ecological and environmental issues can be attributed to the occupation of water body generated by urban land expansion, including: declining of wetland quality, increasing the risk of sandstorms, threatening the safety of drinking water and aggravating the urban heat island effect, etc. Although countries have made great efforts to protect water resources, the results of this study show that the problem of water bodies being occupied by urban expansion is still serious. Under the special national conditions and policy background, this problem appears to be particularly serious in China. To prevent more water bodies from being encroached by urban land expansion, feasible suggestions China could adopt are as follows: 1) Continuously paying attention to the expansion of urban land across the country; 2) Scientifically planning the layout of land use; and 3) Actively promoting wider international cooperation.
In order to struggle with drought proactively and reduce the adverse effect of drought on agriculture, animal husbandry and forestry production in North China, it is necessary to take effective monitoring measures to reflect the drought accurately and timely in North China. However, the existing drought researches only apply a single drought index to areas with relatively homogeneous underlying surface, and rarely consider the applicability of remote sensing drought index under the influence of different underlying surfaces. Therefore, the North China with a more complicated underlying surface is selected as the study area. This study area is a typical climate vulnerable area in China, and it is also an area where the contradictions between population, resources and environment are more serious. In order to provide an effective scientific basis for the decision-making of drought control and drought resistance in the region, an appropriate drought index, on the basis of verification, is selected to analyze the temporal and spatial characteristics of drought in North China. Based on MODIS data, the crop water stress index (CWSI), vegetation water supply index (VSWI), conditional vegetation temperature index (VTCI) and temperature vegetation drought index (TVDI) of the crop growing season (April-October) from 2001 to 2018 were retrieved. Correlation analysis was conducted with relative moisture of soil at 10cm and self-calibrated Palmer Dryness Index (SC-PDSI). At the same time, the appropriate remote sensing drought index was selected to analyze the spatiotemporal variation characteristics of drought in North China through cumulative anomaly analysis, Sen trend analysis, Mann-Kendall test method and gravity center transfer theory. The results show as follows: 1) The four remote sensing drought indexes have better monitoring effects on the moisture of surface soil, but CWSI and VSWI are more suitable for monitoring soil water in North China, and CWSI is more sensitive to soil drought monitoring. In addition, the CWSI drought monitoring effect is better in the grassland and agricultural areas, while the VSWI drought monitoring effect is better in the forest and desert areas. 2) The drought trend in North China has slowed down. The more severe drought years are 2001-2007 and 2009, and 2007-2011 is the transition period from drought to humid. 3) The spatial distribution of drought in North China shows a trend that the north is larger than the south, and the west is larger than the east. The Alashan Plateau has the most serious drought, while the Greater Khingan Mountains almost has no drought. In addition, VSWI is more representative in describing the percentage of the area occupied by drought grade in the entire North China. The percentage of the area occupied by drought grade in descending order is: no drought>extreme drought>moderate drought>mild drought>severe drought. 4) The drought in North China showed a good development trend as a whole. Drought mitigation effect is better in most areas, especially the agricultural areas in southern Ordos, Shanxi Province, Yanshan Mountains and the junction of North China and Northeast China. In addition, the center in drought-prone areas tends to move westward on the whole. Selecting the two most suitable drought indices on the basis of verification to monitor drought in North China can better reveal its temporal and spatial changes. CWSI and VSWI can be used in regional drought research, which can make up for the defects of large scale heterogeneous underlying surface drought research, and can effectively reveal the spatiotemporal characteristics of drought on complex underlying surface. This is of great significance to the sustainable development of regional agriculture, animal husbandry and forestry. The research results of this paper, such as CWSI and VSWI can more accurately reflect the research results of surface soil moisture to a certain extent, could provide references for regional agricultural drought monitoring, and provide scientific basis for regional disaster prevention and mitigation decisions.
Snowfall in China has significant uncertainty and spatial differences, and its response to climate change is complex. Therefore, it is of great scientific significance to analyze the characteristics of snowfall along the north-south transition zone of the Qinling Mountains. Based on the daily meteorological data of 72 stations, we analyzed the type of snowfall (rain, snow, and sleet) along the northern and southern boundaries of the Qinling Mountains in the cold season (occurred from November to the following May) during 1970/1971-2018/2019. The study focuses on the spatiotemporal variation of snowfall, and the response relationship between snowfall, air temperature and wet bulb temperature was analyzed. According to the continuous change characteristics of the sea surface temperature anomaly in summer, autumn and winter Niño 3.4, we further identified the 4 types ofdifferent development El Niño-Southern Oscillation (ENSO) events to reveal that the relationships between different developing ENSO events and snowfall anomalies. The results showed that 1) Snowfall in the north and south of the Qinling Mountains showed a fluctuating deceasing trend in winter. Compared with the average snowfall in 1970-2000, there was a trend that in the south slope of the Qinling Mountains (warm temperate zone) decreased by 3.1 mm in recent 29 years, which was basically equal to the snowfall in the Guanzhong Plain (17.1 mm). 2) Considering the isoline of 1000 m as the dividing boundary, the snowfall in the low-altitude valley (<1000 m) did not show an obvious changing trend, while the snowfall in the high-altitude mountain area (>1000 m) showed a significant decrease. 3) As for the response relationship between snowfall and temperature, the air temperature or wet bulb temperature increased by 1.0℃ from November to March of the second year, and the snowfall in alpine area of the Qinling Mountains decreased by 23.1 mm and 24.3 mm respectively. However, the air temperature or wet bulb temperature increases by 1.0℃ from north to south, the snowfall decrease by 3.0 mm and 2.8 mm in zonality, respectively. 4) The analysis showed that from the perspective of disaster-forming factors, the types of ENSO events affecting the snow anomaly to the north and south of the Qinling Mountains are mainly successive El Niño events. When the successive El Niño/La Niña events occurred, anomalously more snowfall in Guanzhong Plain. When the developing La Niña events occurred, anomalously less snowfall in the Qinling and Dabashan Moutains. When the developing El Niño events occurred, the below normal snowfall in eastern of region and Guanzhong Plain.
Based on long-time series of surface water remote sensing monitoring data from 2001 to 2018, the information of surface water area in the five countries of Central Asia was extracted. We revealed the spatio-temporal features and driving force of their surface water area dynamics using the dynamic degree index, the slope analysis method, and correlation analysis method. The results show that: 1) The spatial distribution characteristics of the surface water of the study area were “dense in the north and sparse in the south”, and the surface water had an obvious change in the central and northern areas. In the past 18 years, the area of seasonal water increasing by 133.55%, while the area of permanent water showed a fluctuating decrease by 17.27%. The largest proportional area of surface water was Kazakhstan with the most obvious changes, followed by Uzbekistan. The surface water of the other three countries had no evident change. 2) From 2001 to 2018, the dynamic degree index of seasonal water areas in five Central Asian countries was the largest value by 7.42% and showed a fast-slow-fast growth trend. In contrast, permanent water showed a growth-decline-growth evolution trend. The dynamic degree index of the surface water area of Uzbekistan was a maximum than other countries. The area of permanent water significantly decreased in the northern edge and Turgai Depression, the Caspian Sea of the western coast, and the Aral Sea, while that the area of the seasonal water significantly increased. The permanent water conversion to seasonal water was evident in those areas. 3) The increasing trend of temperature in the five Central Asian countries was not evident, while the precipitation decreased. The population, GDP, and cultivated land were increasing. The area changes of surface water of the five Central Asian countries were mainly affected by social and economic factors, while the impact of climate factors on surface water was not significant.
