It is of great significance to explore the future urbanization path of China under the background of the slowing urbanization. Based on the multi-source migration data, this article discusses the relationship between urban administrative hierarchy, urban size and urban population attractivity. With the increase of urban administrative hierarchy and urban size, the urban population attractivity increase. The attractivity of municipalities (province-level city), provincial capital cities and separately planned cities are higher than that of ordinary prefecture-level cities, especially far higher than that of county-level cities (counties). Measured by the number of people attracted by the existing population per capita, the attractivity of separately planned cities, provincial capital cities and higher-level and larger municipalities (province-level city) is basically in the same range, which means that these cities are already close to the maximum city size. The population attractivity of county-level cities (counties) is increasing dynamically, while those of other cities are decreasing. Rural migrants are more inclined to migrate to low-level cities than urban migrants. The new urbanization policy, which takes counties as important carriers, is necessary to advance the urbanization process and promote the coordinated development of urban and rural areas. The policy is also in line with the trend of population migration, and adapts to the urbanization of rural areas. In view of the lack of population attractivity of county-level cities (counties), the transfer of rural population to county-level cities (counties) would be a policy-supported urbanization, which is simultaneous with the spontaneous migration to high-level cities. The organic combination of market and government is precisely the advantage of China’s governance. In addition, the provincial capital cities of the eastern, central and western regions almost have the same population attractivity. Therefore, the urbanization of different provinces can form a system with provincial capital cities as the center in the context of population returning to the central and western regions. While provincial capital cities begin to face agglomeration diseconomy, the development of sub-center cities is important.
Education equity is an important basis of social equity. The spatial inequity of basic education resources is a key issue that needs to be solved urgently in China. However, there are still some deficiencies in the existing research. Firstly, the existing research scale of educational accessibility is concentrated at the municipal, county or community level; Secondly, the existing national or regional accessibility research focuses on the evolution of city accessibility in the region in the context of the development of high-speed rail, expressway and other transportation networks; Thirdly, there is a lack of precise calculation of the time spent by residents arriving at educational facilities at the national level. Based on POI, DEM, transport network, land use, population grid data, this study analyzes the accessibility patterns of basic education facilities nationwide by using the methods of cost-distance grid analysis, population-weighted Gini coefficient, and two-variable Moran’s Index calculation, and evaluates the multi-scale fairness of basic educational accessibility. The study found that: 1) The 15-minute isochron of primary and secondary schools covered 79.7% and 78.8% of the population of the country respectively, and the terrain with high accessibility was mainly plain and basin, mostly distributed in urban agglomerations and metropolitan areas; 2) At the county level, the “high level” and “high balance” of accessibility are clustered and distributed. The two-variable Moran’s Index of population coverage and accessibility variation coefficient are –0.602 and –0.587, respectively, that is, areas with high service levels and their surrounding areas tend to be well balanced; 3) At the provincial level, the “high level“ of accessibility does not coincide with the “high balance”. The Gini coefficient in Beijing and other areas with high accessibility of basic education reaches more than 0.7. Generally, the more complex and diverse the natural geographical environment, the lower the fairness of accessibility of basic education between counties. It is suggested to strictly regulate the withdrawal and merger of schools in rural areas, give play to the role of inter-regional transfer payment in improving basic education facilities, and provide good travel conditions for primary and secondary school students.
In recent years, alternative agricultural production has gradually become an important support for sustainable food systems, and an important hand in interpreting the complex interrelationships within social-ecological systems. This article takes Yinlin Farm in Conghua District, Guangzhou City, as a case study site to explore the vulnerability problem of alternative agricultural production from the perspective of social-ecological system and the formation mechanism of the resilience network of alternative agricultural production. The study shows that: 1) The vulnerability problem of alternative agricultural production is mainly due to the structural political economy elements in the social-ecological system, including the asymmetry of agricultural subsidy policy, the damage to soil structure and instability of germplasm resources, and the non-mainstream nature of the agricultural market. 2) The mechanism of forming a resilient network of alternative agricultural production from the perspective of the social-ecological system includes the resilient social relationship network of linking subjects and norms, the resilient knowledge exchange network of scientific and local integration, and the resilient consumer market network established by mutual trust and identity. 3) The formation of a resilient network of alternative agricultural production is essentially a process of building the resilience of the social-ecological system, and alternative agricultural production and the social-ecological system are mutually constructive. The study reveals the formation mechanism of the resilience network of alternative agricultural production from the perspective of the social-ecological system, which enriches the connotation and extension of the resilience theory in the field of agricultural production; and discusses the possible development trend of the resilience network of alternative agricultural production at the practical level, which provides a reference basis for the construction of China’s sustainable agricultural policy and guarantee system.
Since the reform and opening up, the rapid expansion of Chinese city leads to the separation of occupation and housing and traffic congestion. Rail transit is an important means of relieving commuting pressure in cities. Current studies mainly explore the effect of built environment on rail transit commuting based on the geographical background of residence, but less explore the effect of built environment at workplace. Taking Wuhan City as an example, this study identified rail transit commuters and constructed commuter travel chain through smart card data of 189 stations. Gradient Boosting Decision Tree (GBDT) was used to analyze the nonlinear influence mechanism of 30 factors, including the built environment of residence and subway station characteristics, on commuter ridership and commute time. The results show that: 1) The commuter ridership in residential areas presents a centralized point-like distribution, and the commuter ridership in employment areas presents a significant “center-periphery” structure, and the spatial pattern of commuting time of residence and workplace presents a low distribution in the middle and high distribution in the periphery. 2) All job residence built environment factors on the rail transit commuter ridership and commuting time is widespread nonlinear effect and the threshold effect, overall residence built environment relative influence degree is higher than the workplace, but the job the company formed in workplace is the most important factors affect the commuter ridership, the distance between workplace and city center is the most important element in commuting time; 3) The same built environment factor of residence and workplace may have similar or opposite effects on the commuter ridership and commuting time, which is related to the construction of urban rail transit network and the actual social development. The results of this study can better correlate the built environment of dismissal residence with the commuter characteristics of rail transit, and contribute to the coordinated development of rail transit and urban employment-residential space.
Based on the data of Singapore-invested enterprises in China, this paper analyzes the spatial-temporal characteristics and influence mechanism for of Singapore-invested enterprises entering the industrial park in China from 1979 to 2022. The spatial-temporal characteristics of the Singapore-invested enterprises are studied in depth by adopting the spatial analysis technique from ArcGIS software, and the empirical method is used to investigate the influence mechanism of industrial park in promoting the entry of Singapore-invested enterprises. The results show: 1) The number of Singapore-invested enterprises shows obvious fluctuation at individual time points, the number of new founded Singapore-invested enterprises has experienced 3 peaks, which are 1993, 2006 and 2021, and the proportion of Singapore-invested enterprises entering industrial park has increased sharply during the period from 1979 to 2009. 2) In terms of spatial characteristics, the overall degree of agglomeration of Singapore-invested enterprises continued to rise from 1992 to 2022, and the proportion of Singapore-invested enterprises entering the industrial park and those entering outside the industrial park were similar, showing a similar spatial distribution pattern. 3) The increase in the number of industrial park can promote the increase of Singapore-invested enterprises, and the construction of industrial parks promotes the entry of Singapore-invested enterprises through 2 main mechanisms: First, industrial parks help to improve the level of infrastructure construction in 3 regions, thus providing convenient conditions for the entry of Singapore-invested enterprises. Second, industrial parks play a key role in reducing the tax burden on foreign enterprises, which further incentivizes these firms to conduct business in the industrial park. Focusing on new ventures, this paper not only provides a strong basis for an in-depth understanding of the development of foreign investment in industrial parks in China, but also provides substantial support for attracting high-quality foreign investment and promoting high-quality synergistic development of local industries. The findings of the study improve the explanation of the mechanism of foreign-invested enterprises entering the parks in China, enrich the geographic study of foreign investment, and provide significant insights in optimization of foreign investment policies and the construction of industrial park.
Land use/cover change (LUCC) in historical period is an important part of global change research. For historical LUCC over a period of more than 100 years, due to the lack of direct data with clear spatial attributes, the main way to explore this problem is to collect various proxy data and combine geographic modeling to reconstruct the spatial pattern of historical LUCC on the basis of in-depth understanding of the past spatio-temporal evolution process of land use/cover. China’s rich historical literature is the key data source for the reconstruction of long-term LUCC data sets. Continuously mining, compiling, and updating historical data sources from the literature is the basis for the continuous advancement of research. This paper analyzes the existing LUCC reconstruction data set in China from the perspective of the application of historical literature data sources. The land use data sources contained in the historical literature are summarized into 4 main types: Statistics, enumeration, description and image. Historical statistics combined with modern impact factors, historical statistics combined with enumerated data, historical data sources based on descriptions, and historical data sources based on images are the main methods for reconstructing LUCC datasets using historical data sources. The recovery and revision of statistical data, the spatialization of enumeration and description data, and the precipitation of image data are the main means for the preparation of historical data sources. The current reconstruction data set is reviewed from the application status of various data sources, data preparation methods and other aspects, and the main characteristics and problems of the reconstruction research application of historical literature are summarized, The future development trend of LUCC reconstruction historical literature application and historical data source preparation is prospected from the aspects of comprehensive utilization of multiple historical data sources, adjustment of reconstruction ideas, and use of modern information technology to improve data preparation efficiency.
The migratory birds, constituting individuals engaged in seasonal migration, represents a prominent area of inquiry in the study of population migration. This article presents a comprehensive synthesis of pertinent scholarly literature, systematically summarizing the identification pathways, migration scale and characteristics, migration motivations, social effects, and social integration pertaining to the migratory birds. Current research indicates that the migratory birds, primarily comprising middle-aged and elderly individuals, undertake extensive, long-term, and large-scale migrations to regions endowed with superior natural environments, driven by their quest for enhanced well-being. Migration motivation is influenced by factors encompassing living environments, social relationships, economic motivations, and healthcare services. Ongoing researches on the social effects of migration continue to generate debate. The migratory birds exert multifaceted impacts on the socio-economic fabric, with the majority of scholars acknowledging their positive effects on local economic development, industrial restructuring, and social interactions. However, a subset of scholars posits that the cyclical flow of the migratory birds engenders challenges such as seasonal shortages of public service resources during peak periods and underutilization of commercial land during off-peak seasons. Moreover, the issue of social integration of the migratory birds has gained increasing scholarly attention, with a prevailing consensus that the migratory birds exhibit relatively low levels of social integration. Further endeavors to deepen interdisciplinary integration of disciplines such as demography, geography, and sociology, while expanding the repertoire of identification and data collection methodologies for the migratory birds, should be directed towards an exploration of the distinctive characteristics of population migration in the “era of the migratory birds” from the perspective of human geography. This entails heightened research focus on emerging domains such as “migratory talent”“reverse migration”“sunbird” and “cross-border migrants” thereby facilitating the provision of a more scientifically rigorous foundation for second place of residence planning and social policy development.
Taking 270 prefecture level and above cities in China from 2008 to 2021 as research objects, this study explores the spatial differentiation of urban economic resilience from the perspective of industrial structure upgrading, and its driving factors. The research results indicate that: 1) In terms of time dimension, the overall resilience of urban economy shows a fluctuating upward trend, with a relatively high overall level, but there is still a significant improvement space of 29.7% (or even more) in regional differences; In terms of spatial dimension, the resilience of urban economy shows a pattern of the western China>the eastern China>the central China. 2) The upgrading, rationalization, and ecologicalization of industrial structure have significant spatial heterogeneity on the resilience of urban economy, exhibiting a spatial band or patchy distribution pattern. Among them, the upgrading of industrial structure has an overall positive promoting effect on the urban economy; the impact of rationalization of industrial structure is manifested as a gradual positive effect from the north China to south China; the ecological transformation of industrial structure has a significant inhibitory effect on the resilience of urban economy; other variables have a significant positive and negative dual impact on urban economic resilience. 3) From the spatial heterogeneity characteristics of the driving factors of urban economic resilience, the advanced industrial structure and population density dominate the southeast China; the driving factors for the rationalization of industrial structure dominate the southwest China; the driving factors of ecological industrial structure, industrial agglomeration level, and local fiscal gap dominate the northwest China; the driving factors of globalization level and technology investment level dominate the northeast China; each driving factor dominates the north China region on average and forms its own category.
Understanding the spatial structural evolution of Ecological Urban Tourism Complexes (Eco-UTCs) is crucial for enhancing urban green growth and refining the urban functional structure. Taking Lingshan Bay in Qingdao as a case, this paper investigates the spatial structural evolution characteristics of Eco-UTC from a topological perspective through the combination of space syntax and GIS analysis tools. Findings reveal that: 1) From 2009 to 2021, the spatial integration, permeability, and intelligence of Lingshan Bay Eco-UTC have continuously increased; 2) A temporal shift in Lingshan Bay Eco-UTC from a dispersed to a consolidated spatial structure, progressing from limited inland development to ordered coastal expansion. This evolutionary path can be characterized as “finger-like growth, axial expansion, and centralized integration”; 3) From the perspective of the tourism man-land relationship, this spatial patterning originates from the comprehensive effect of resource availability, administrative directives, economic drivers, market demands and other factors. Essentially, under the guidance of evolving urban development, urban space, acting as a geographical factor, employs resources, economics, market, and administrative factors as mediating elements, exerting a directional effect on Eco-UTCs, which serve as a representation of human economic activities. Furthermore, Eco-UTCs proactively adapt to the adjustments in the external environment through spatial reconfiguration. This paper discovers that, grounded in a scientific understanding of the complexity and multi-faceted drivers behind the spatial evolution of Eco-UTCs, the precise steering of these driving elements towards rational flow and efficient allocation emerges as an effective strategy for advancing both the intensive growth of Eco-UTC spaces and the exponential enhancement of urban leisure vitality. In light of these findings, several strategies are proposed for the development of high-quality Eco-UTCs. Firstly, it is imperative to delve deeply into the multi-faceted service value of ecological resources, while preserving their natural state. By integrating local cultural and historical assets into the ecological landscape creation, a distinctive and high-quality Eco-UTC can be achieved. Secondly, the government’s leading effects should be leveraged by implementing a series of beneficial industrial policies, enhancing urban transportation systems, and nurturing superior leisure projects. This can optimize the allocation of leisure elements and strengthen both internal and external spatial connections, enabling resource sharing and cross-regional collaboration. Lastly, increasing investment in ecological protection and services is essential. While optimizing the aesthetic and infrastructure of the Eco-UTC, efforts should be made to ensure complementarity and balanced development among various functional zones within the domain.
Geographic distance has always been regarded as an important parameter for understanding tourism demand and tourist behavior. Based on the questionnaire survey data of tourists choosing homestay in Yangshuo County, Guilin City, this study applies structural equation modeling to analyze the influence mechanism of multidimensional distance on tourists’ intention to choose homestay, and tests the moderating effect of host-guest interaction. The research results are as follows: 1) The multidimensional distance framework can explain the behavioral intention mechanism of homestay tourists. Space distance, economic distance, and location distance enhance the image of homestay, while location distance weakens homestay attachment. 2) Homestay image and attachment play a significant mediating role between multidimensional distance and behavioral intention of homestay tourists, and homestay attachment plays an important mediating role between homestay image and behavioral intention. 3) The interaction between host and guest plays a differentiated moderating effect in the behavioral intention model of homestay tourists. Information interaction plays a positive moderating role in the relationship between homestay image and homestay attachment, and interpersonal interaction plays an negative moderating role in the relationship between economic distance and homestay image. Service interaction positively moderates the impact of spatial distance on homestay image, while negatively moderates the effect of homestay attachment on behavioral intention. The analysis of the impact of multidimensional distance on tourist behavior intention not only reveals a new type of human-environment relationship, enriches social interaction theory and the gravitational mechanism of distance, but also expands the research literature of tourist behavior intention, and provides a new explanatory perspective for tourism behavior decision-making mechanism.
With a growing trend of family migration, children are increasingly on the move. For children on the move, the most direct experience is the transformation of their homes. “Home” is one of the most important research topics in cultural geography, however, existing literature in human geography tends to focus on adults’ experiences, leaving the experiences and subjectivities of migrant children, an integral part of the migrant population, under-researched. Taking QX Village in Panyu District of Guangzhou City as a case study site, this article discuss migrant children’s imaginations of “home” at different scales from a critical geography perspective by analyzing their paintings. To be specific, use children’s art production as the primary research method, supplemented by participatory observation, text analysis and in-depth interviews to fully unpack migrant children’s perceptions of “home” at different spatial scales and its rich material and emotional components. The results show that: 1) The element of “home” in the paintings of migrant children consists of the elements of the natural environment and the elements of humanities and culture, which is not only the expression of migrant children’s life experience, but also the expression of imaginations and expectations of “home”, and that the material and emotional dimensions of “home” are related to each other and have mutual influences on each other. 2) In the context of mobility, the concept of “home” is closely linked to not only the physical dwelling but also the community and even broader spatial connections. Children have developed a fluid and multi-scalar perception of “home”, encompassing the scales of residence, community and city, with the community being an important medium for migrant children to establish positive emotional connections with a place. 3) In the drawings, “Home is far away from hometown” is a common perception among migrant children, and “home” always points to the place where the household registration is located, which reflects the mismatch between migrant children’s daily life space and the place of “home”. In this sense, the geographical location of home does not change with mobility and the hometown remains an ideal and beautiful space. Findings of this study aim to provide a new theoretical perspective for the study of migration in human geography in China, offer detailed empirical evidence for the construction of “human-centered new urbanization” and provide important implications for urban managers to create a friendly environment for the integration of migrant children.
Ecologically sensitive network is a kind of ecological structure model that simulates negative ecological links between ecologically sensitive areas by establishing interconnections between ecologically sensitive discrete and isolated areas in terms of structure and function. This paper first defines the concepts related to ecological sensitivity network, constructs the research framework of ecological sensitivity network, takes Shaanxi Province as a case study, evaluates its ecological sensitivity using the method of physical quality assessment, and constructs the ecological sensitivity network on the basis of the results are as follows: 1) The spatial distribution of ecological sensitivity in Shaanxi Province varies significantly, and the extremely sensitive areas and sensitive areas are mainly distributed in the wind-sand plateau north of the Great Wall, the loess plateau in northern Shaanxi Province and the Guanzhong Plain, southern Shaanxi Low Hilly Basin and northern Weibei Plateau Hilly Gully Area. 2) A total of 34 ecologically sensitive patches, 50 sensitive nodes and 77 sensitive corridors have been screened out, and the ecologically sensitive network is densely distributed in the northern part of Shaanxi Province, sparsely distributed in the central part of the province, and basically non-existent in the southern part. 3) The Huanglong Mountains-Ziwu Ridge plays an important role in blocking the connection between dense and sparse ecologically sensitive network areas, and the Qinling Mountain Range plays a key role in blocking the flow of negative ecological flows from ecologically sensitive networks to ecologically functionally important areas. 4) The ecological restoration pattern suggests that ecological restoration space can be reserved in river and traffic restoration corridors by increasing ecological restoration patches to better block ecological flows between sensitive sources. The results of the study can provide a scientific basis for improving the construction of ecological restoration patterns.
Microbes play an important role in improving soil fertility and nutrient cycle. Exploring the soil microbial community characteristics under different revegetation types can provide scientific basis for the restoration and reconstruction of karst degraded ecosystem. In this study, 5 vegetation restoration types (i.e., Macadamia integrifolia, Juglans regia, Morus alba, Caesalpinia sappan and enclosure forest) were selected to analysis the α diversity and community structure of soil bacteria and fungi and their controlling factors. Results showed that compared with the abandoned land, vegetation restoration had a significant impact on soil physical and chemical properties, with the greatest effect of enclosure forest on improving soil organic carbon (SOC) and nitrogen and phosphorus nutrient content. Different types of revegetation enhanced the α diversity of soil microorganisms in different degrees, with the most significant influence on bacterial richness and pedigree diversity under Morus alba, and on fungal richness and shannon index under Juglans regia. Soil pH, NO3 − and Ca2+ contents were positively correlated with bacterial α diversity (richness, shannon index and pedigree diversity index). Revegetation significantly changed microbial community structure, which was mainly manifested in that compared with abandoned land, Juglans regia significantly increased the relative abundance of Planctomycetes and Basidiomycetes, and Macadamia integrifolia significantly increased the relative abundance of Ascomycetes. Redundancy analysis showed that the contents of soil Ca2+ and TN were the relative important influencing factors of microbial community structure. Our findings indicate that the plantations of Morus alba and Juglans regia had a remarkable effect on improving microbial diversity, which will help to improve the stability of soil ecosystem. Macadamia integrifolia significantly increased the abundance of Ascomycota, which may play an important role in enhancing soil erosion resistance. Natural enclosure forest had obvious effect on increasing soil organic carbon, nitrogen and phosphorus nutrients, which is of great significance to improve soil fertility in karst degraded ecosystem.
In order to study the response of tree growth to north-south climate change in the subtropical and warm temperate climate transition zone, taking Pinus tabuliformis forest of the Jigong Mountain Nature Reserve in Xinyang City, Henan Province as the research object, the radial growth width chronology of it is established using the tree ring method. The characteristic values of chronology show that the standard chronology of high quality containing many climate information can reflect the impact of climate change on tree growth. The analyses of the standard chronology and meteorological factors of the north and south weather station of the Jigong Mountain find that: The growth of Pinus tabuliformis is not only negatively correlated with the temperature, but also positively correlated with the relative humidity in almost all months, significantly with May-July temperature (mean temperature in June, mean maximum temperature in May and June, and mean minimum temperature in June and July) of the Macheng meteorological station on the south side of the Jigong Mountain, which shows that the soil water stress mainly limits the growth, caused by high temperature in the south side of the transition zone; and the April-June (late spring and early summer) relative humidity is the limiting factor for the growth of Pinus tabulaeformis on the south side of the Jigong Mountain. However, the August-September temperature (the mean temperature in August and the mean minimum temperature in August and September) has an obvious effect on promoting the growth of Pinus tabulaeformis, and July-August relative humidity of last year is the limiting factor of Pinus tabulaeformis’ growth on the north side of the Jigong Mountain. The precipitation in September (the late growing season) had a lag effect on the growth of Pinus tabulaeformis. In the moving correlation analysis, there is a enhanced trend positively responsing the August-September mean temperature of Xinyang meteorological station on the north side of the transition zone in recent years. Therefore, under the climate warming, the southern boundary of Pinus tabulaeformis may move toward the north due to high temperature inhibition (negative correlation with the temperture of subtropical Macheng). The aim of the study is to provide a basic data support for forest management and renewal in transition zones through studying the growth dynamics of Pinus tabuliformis in response to climate warming.
Based on the establishment of the reliable stratigraphic chronology of SZK1507 lacustrine core in the center of the ancient lake basin on the west bank of Chaohu Lake, the correlation and principal component analysis of the geochemical elements of the core showed that the principal component F1 reflected the intensity of erosion capacity in the basin, F2 was sensitive to the strength of the basin’s chemical leaching, and F3 indicated the level change of the lake. Combined with the environmental proxy of Rb/Sr value, the regional hydrological climate evolution with high resolution since Holocene in Chaohu Lake since Holocene was reconstructed with high resolution. The results showed that the process of the environmental evolution in this region could be divided into 7 stages. The climate of Period I (about 10.8 cal. ka B.P.—9.9 cal. ka B.P.) and Period III-Period V (from 9.3 cal. ka B.P. to 4.2 cal. ka B.P.) was relatively humid with the high-water level in Chaohu Lake. During the Period II (from 9.9 cal. ka B.P. to 9.3 cal. ka B.P.) and the Period VI (from 4.2 cal. ka B.P. to 2.3 cal. ka B.P.), the overall climate became dry, resulting in decreased precipitation, the lake shrinkage and the dropped lake level. Unlike the previous stage, although the regional climate fluctuated significantly with alternating dryness and wetness, it tended to dry out as a whole in the Period VII (from 2.3 cal. ka B.P. to the present). Abrupt climate events like 9.3 cal. ka B.P., 8.2 cal. ka B.P. and 4.2 cal. ka B.P. events were also reflected in this sedimentary record. By comparing the Ti element intensity, principal component F1 and Rb/Sr ratios of lacustrine sediments in Chaohu Lake with the 30°N summer solar insolation, Ti content in Cariaco basin, ENSO activity index during the Holocene et al., we found that the abrupt climate events in the study area were mainly controlled by the variation of summer solar insolation in the northern hemisphere, the average latitude of ITCZ and the frequency of ENSO activity. The summer solar insolation in the northern hemisphere reduced, ITCZ moved southward, ENSO activity frequency increased, and the summer monsoon weakened, led to the occurrence of dry and cold events such as 9.3 cal. ka B.P. event. The results will provide a reliable basis for understanding the relationship between the East Asian Monsoon and the evolution of hydrology and climate since Holocene.
In this article, based on the results of grain size measurements, the sedimentary environment of the dammed lake formed by the Xiayuan landslide in the Chenghai-Binchuan fault zone, an area prone to frequent earthquakes, is analyzed using graphic methods and fractal theory. The study discusses the applicability of traditional indices in the sedimentary analysis of dammed lake and explores the potential value of multifractal theory in sedimentology. The results indicate that: 1) The grain-size statistical parameters of sediments from the dammed lake exhibit distinct differences compared to those formed in other environments. They show unique distribution curves, sorting states, and fractal characteristics typical of fluvial-lacustrine sediments. The dominant grain size significantly influences the fractal calculations, with the global fractal dimension correlating well with the sorting coefficient. Different fractal dimensions correspond to varying sedimentary conditions within the dammed lake, suggesting that fractal dimension has promising applications in grain size analysis of dammed lake. 2) The multifractal analysis reveals that sediments from the dammed lake, observed in two distinct periods, are characterized by a high aggregation of components. This indicates a concentrated grain size distribution, reflecting the hydrodynamic stability of the dammed lake during sedimentation and the distinctiveness of the sedimentary source, which further supports the notion that the dammed lake has been in existence for an extended period. The sedimentary grain size distribution of the fine grain group is narrow, with a relatively concentrated distribution. Although there are many dominant grain groups, each has a low individual content, low tail content, and significant internal variability. In contrast, the distribution of coarse grain groups shows low concentration and high dispersion. High aggregation grain groups are few but have high content, while low aggregation grain groups are numerous but have low individual content, displaying a pattern of high concentration in the center and low on the periphery. 3) Multifractal analysis indicates that Δα and Δf are effective for analyzing the internal distribution characteristics of grain groups in sediment size analysis, providing insights that traditional indicators cannot replace. D 0 and D 1, when combined with other q-order multifractals, can serve as alternative indices for sedimentary environment analysis, while D 1/D 0 and D 2 are less applicable.
Drought is a type of natural disaster that lasts for a long time and causes a lot of damage. It has a negative impact on the security of the water supplies in the region, human production and life, and economic growth. In order to analyze the spatial-temporal characteristics and underlying causes of vegetation drought in the middle Yellow River from 2000 to 2021, the temperature vegetation Precipitation Drought Index (TVPDI) was developed in this study using normalized vegetation index, surface temperature, and precipitation data. Additionally, the relationship between the implementation of the project to convert farmland in the middle Yellow River to forest and grassland and regional vegetation drought was examined. The findings revealed that: 1) The multi-year average TVPDI value in the middle reaches of the Yellow River from 2000 to 2021 showed an insignificant upward trend, and the average multi-year TVPDI value was 0.708, corresponding to a light drought grade. 2) TVPDI in the middle reaches of the Yellow River from 2000 to 2021 has a strong spatial differentiation, showing a spatial distribution pattern of “drought is lighter in the northeast and southwest regions and heavier in the northwest and southeast regions”; From the perspective of each geomorphic region, the drought in the loess plateau gully area is light, and the drought in the wind-sand area and the valley plain area is heavy. 3) The main factors affecting the spatial differentiation of TVPDI in the middle Yellow River are temperature, evapotranspiration and rainfall, and there is a significant linear relationship with TVPDI. In the middle reaches of the Yellow River from 2000 to 2021, vegetation coverage and evapotranspiration showed an increasing trend, while soil moisture showed a decreasing trend.
In order to understand the influence of different statistical methods on sediment source identification, and then select a reasonable statistical method, so as to more accurately identify the sediment source contribution of different sources in karst depression small watershed, so as to formulate more effective sediment control measures. In this study, the Qingmuguan karst depression basin was selected as the research area. Soil samples from 3 sediment sources, forest land, grassland and sloping land, and sediment samples from depression were collected, and 26 indexes including magnetic susceptibility, TP, TC, TN, 137Cs and geochemical elements were determined. Three groups of optimal fingerprint factor groups were selected by 3 statistical analysis methods. The results are found: Kruskal-Wallis H test (KW-H) combined with discriminant function analysis (DFA), Principal component analysis (PCA) combined with DFA, and KW-H combined with PCA were used to estimate the relative contributions of the 3 potential sources. The results showed that the relative contribution of forest land, grassland and slope land was 25.17%, 32.19% and 42.64%, respectively, estimated by KW-H+DFA. The relative contributions of PCA and DFA were 26.72%, 29.14% and 44.14%, respectively. The relative contributions estimated by KW-H+PCA were 23.67%, 27.36% and 48.97%, respectively. The GOF, RMSE and MAE of different statistical combinations were 94.47%, 9.85 and 5.71, respectively. RMSE of different statistical combinations were 91.32%, 19.95, 10.08; The MAE of different statistical combinations were 90.11%, 20.76, 12.12. The results show that different statistical methods will affect the discriminant analysis and accuracy of sediment sources. It is emphasized that the selection of statistical methods should be paid attention to in the study of sediment sources, so as to identify sediment sources more accurately and facilitate the implementation of corresponding soil and water conservation measures.
