In the process of rapid urbanization in China, metropolitan outskirts are areas where land use change most frequently occurred and human-nature relationship most complex, and it is very important to understand changes in land management and urban planning in these areas. Constrained Cellular Automata (constrained CA) can simulate complicated urban dynamic changes in accordance with certain simple rules and has become an important tool in the study of spatiotemporal changes of urban land use. Using land use data of Jiangxia District of Wuhan City collected in 2007 and 2011, this study incorporated considerations such as overall land use planning index, strategic arrangement of urban spatial development, and land use constrains into the transition rules of Cellular Automata. Then the logistic regression method was employed to determine the influencing factors of city spatial development and a constrained CA model was established to simulate scenario urban construction of Jiangxia District in 2020. The findings were compared with the prediction of forecast-CA. The simulation results show that: (1) Jiangxia District gradually absorbs some of the functions and population of the city center during the study period, but the urban expansion and land use is of low efficiency. The population of the study area will not grow significantly and the expansion of the area will not ease the high population pressure in the city center. (2) Constrained CA is able to depict a vivid picture of the layout and structure of small towns in metropolitan outskirts and is suitable for land use planning and urban planning. (3) Overlay analysis of the results of scenario simulations can identify the key monitoring areas of land use supervision and provide warning messages for the supervision and control of illegal land use.
With the fifth and sixth census and road network data, and using a spatial interoperability evaluation model and a spatial lag model, the spatial coupling relationship between China's road transport superiority degree and urbanization rate at the county level was analyzed. The result shows that: (1) Regional difference of China's urbanization rate is significant at the county level. Urbanization rate is low in traditional agricultural areas, poor contiguous mountainous counties (districts), and the spatial mismatch between economic development and labor resources was widespread, with urbanization taking place in areas away from residents’ place of origin in underdeveloped areas. (2) Regional difference of road transport superiority degree is clear between the eastern and western regions and between the transport hubs and peripheries, with a clear “point-axis” spatial structure at the regional level. Road transport superiority degree showed a partial normal distribution at the county level. (3) The overall coverage of highways, national highways, provincial highways, and county and township roads affects road accessibility for production flow, information flow, and non-agricultural market entrance of rural production factors, which affect urbanization development at the county level. Urbanization was obviously facilitated by the presence of highway exits and railway stations. (4) The spatial interoperability grade of road transport superiority degree and urbanization rate shows a partial normal distribution, with significantly mutual influence between urbanization and road transport development levels.
Peri-urban areas have been a focus of research by scholars from multiple disciplines including geography, urban and rural planning, ecology, and sociology due to their transitional, diverse, and dynamic characteristics in socioeconomic structure and landscape features. This study examined the change of urban and rural settlements in peri-urban areas during the process of urbanization and the spatial characteristics and mechanism of change of remaining villages. Based on the review of theoretical research on rural settlements in peri-urban areas and taking the Kangdu village in the college town of south Xi’an as an empirical case, this study explored the spatial pattern as well as the mechanism of the change by remote sensing imagery interpretation, field investigation, and statistical analysis. The results indicate that four periods of building construction boom and two significant shifts in employment occurred in the 15 years from 2001 to 2015. Most of the local residents started renting out their houses in 2006. We found a high correlation between the residents’ employment change and the key milestones of urbanization; and there was a clear “stimulation-feedback” mechanism between the change of employment and building boom. This study shows that the external driver of urbanization in close proximity and local residents’ adaptation were the main driving forces of change in rural settlements’ spatial pattern in peri-urban areas.
The efficiency of public space network structure reflects the ability of communities to reconstruct their social network, to accumulate social capital, and to rebuild social order. In recent years, as a new form of living and emerging in large numbers, new concentrated communities are facing enormous pressure in reconstructing social relations. Using Social Network Analysis, this study found that: the public space network correlation degree is 0.216, central potential is 0.358, and small world business value is 1.978. These show that the overall association degree of the spatial network is insufficient and the network is fragmented; the integration effect of commercial space is affected by the configuration of businesses; and the social attributes of residents influence the characteristics of the spatial network structure. Finally, with regard to concentrated resettlement model and pubic space network optimization, the author puts forward the direction of further research of new concentrated communities, in order to provide a scientific basis for the current and future planning and development and overall optimization of public space of concentrated communities.
Chinese traditional villages built before 1980 are the carrier of farming civilization and traditional cultural heritage. Traditional villages formed during different historical periods and under specific geographical conditions reflect the economic, political, cultural, and other social aspects during their development. However, with the rapid progress of urbanization, traditional villages are disappearing. Protecting these villages is of significant importance in modern society. Based on the list of traditional villages published by the Ministry of Housing and Urban-Rural Development, 2555 villages were selected as the research object of this study. By using GIS technology and kernel density analysis, nearest neighbor analysis, and Anselin local Moran’s I, this article analyzes the spatial distribution characteristics of Chinese traditional villages, examining the relationship between the spatial distribution of traditional villages and terrain, population, economy, traffic, and urban spatial pattern. The result shows that: (1) The spatial distribution of traditional villages clearly varies among different regions of China and four concentrated areas are found in the Hebei-Shangdong-Henan border area, Anhui-Zhejiang-Jiangxi border area, Guizhou- Guangxi-Hunan border area, and northwest Yunnan; (2) Higher altitude (over 500 m) is conducive to the preservation of traditional villages; (3) Population is the basis for the existence and continuation of traditional villages, but does not have a significant correlation; (4) The relationship between regional economic development, transportation development and traditional village preservation should be further studied. On the one hand, economic backwardness and low accessibility through transportation provide an environment conducive for the protection of traditional villages. On the other hand, the development of regional economy and transportation are not necessarily an obstacle for protecting traditional villages; (5) There is a certain degree of negative correlation between the level of traffic development and the number of traditional villages; (6) Spatially, existing traditional villages are often located far from the center of cities, or in urban fringe.
Unsuitable land use is an important factor contributing to ecological problems. Determining ecological red line can coordinate the relationship between land use and the ecological environment, promote reasonable allocation of land resources, and improve regional ecological security. Research on methods to determine ecological red line has theoretical and practical values. Mountain areas have rugged terrain and dense water systems, where fragmentation of land use is often serious. They are also important areas with regard to soil and water conservation and key areas for ecological restoration and reconstruction. Taking a mountainous town—Yihe in Chongqing Municipality—as an example, this study used GIS tools and took into consideration ecological sensitivity and ecosystem services value to determine the rigid and flexible ecological red lines of the study area. This study chose slope, vegetation coverage, water and soil types, and erosive force of precipitation as indicators for ecological sensitivity assessment and food production, raw material production, gas regulation, climate regulation, hydrology regulation, soil retention, nutrient cycling maintenance, biodiversity, and aesthetic as indicators for ecological service assessment. The area within the rigid ecological red line is 43.90 km2, 44.34% of the total area of Yihe Town; and the area within the elastic ecological read line is 29.18 km2, 29.47% of the total area. Ecological red line encloses the northern and eastern mountainous area and southern area with dense water courses of the town. The ecological sensitivity and ecological services value are high is this area. The ecological red lines determined in this study identify key areas for ecological restoration and protection, and the methods and result can support policy-making for improving ecological security of the region.
Landslide pseudo-absence samples play an important role in applying statistical methods for landslide susceptibility mapping. It can constrain the overestimation of landslide susceptibility. The reliability of pseudo-absence samples is unknown in existing methods of pseudo-absence sample generation in landslide susceptibility mapping. The absence samples they generate may contain sites very susceptible to landslides but have not yet failed in the past simply because of the lack of triggering factors. These false absence samples lower the quality of absence samples and in turn lower the quality of the entire training sample set, and then decrease the accuracy of the mapping using statistical methods. In this article, a new method of measuring the reliability of pseudo-absence samples is proposed. The basic principle of the method is that the more similar the geographic environment is between two locations, the closer the geographic features are between them. Accordingly, the more similar the geographic environment of a location is with landslide presence samples, the more likely is the location prone to landslides and the less reliable is this location as an absence sample. According to the inference above, the reliability of a grid as an absence sample can be calculated by the similarity of its geographic environment with the typical environmental conditions under which landslides occurred. The Youfang catchment in southern Gansu Province—an area with high risk for landslides—was used as the study area to apply the proposed method and map the reliability of each grid chosen as pseudo-absence sample. The landslide initial zones in the Youfang catchment were used to validate the effectiveness of the proposed method. The results show that the mean reliability of grids in the landslide initial zones chosen as pseudo-absence samples is 0.26 and the reliability of more than 95% of the grids is lower than 0.5. This indicates that the proposed method of measuring the reliability of pseudo-absence samples is effective.
Digital elevation models (DEMs) have been widely used in soil erosion simulation, but how different interpolation methods affect the simulation results is not well researched. In this article, a typical gully in the dry-hot valley of the Jinsha River was selected as the case study area. First, field measurement of elevations of the gully was preformed. Inverse Distance Weighted (IDW), Disjunctive Kriging (DK), Spline with Tension (ST), and Local Polynomial Interpolation (LPI) methods were then used to produce high-precision DEMs of the gully. The United Stream Power-based Erosion Deposition (USPED) model was used to simulate the spatial distribution of erosion and deposition in the gully. The coefficient of relative difference was used to analyze the similarity of USPED results. The result shows that the precision of DEMs from high to low is: DK, LPI, IDW, and ST. The results of USPED simulation show that DK revealed the main distribution pattern of erosion and deposition, but IDW highlighted the details, and LPI and ST were in-between. The coefficient of relative difference shows that IDW was similar with other interpolation methods in soil erosion simulation, but when the layout of sampling points is reasonable and the density of the sampling points is sufficiently high, IDW is more suitable for soil erosion simulation using USPED.
Based on Landsat MSS/TM/ETM+/OLI images of 1978, 1991, 2001, and 2015, glacier boundaries in the Shaksgam River Basin, Karakoram Mountains were extracted using computer aided image classification and visual interpretation methods, and the changes of glaciers in the study area were analyzed. The results show that the total area of glaciers in the study area was reduced from 1821.70 km2 to 1675.92 km2 during 1978-2015, by 145.78 km2, or 8% of the total area of glaciers. Under the background of climate warming, however, the rate of glacier retreating shifted from fast to slow in nearly 40 years. In the study area, the glacier retreat rate on the southeastern aspect was significantly higher than on the northwestern aspect. Glacier retreat rate decreased with the increase of scale of glaciers. There were 27 typical glaciers that clearly progressed during 1978-2015, with areas and lengths significant increased. Among these, the velocity of change for the western side of the Wood stark glacier was 904 m/a during 1996-1998, the velocity of change for the eastern side of the K2 glacier was 446 m/a during 2007-2009, and the velocity of change for the 5Y654D497 glacier was 238 m/a during 1978-1990, respectively. These three glaciers seem to be the surge-type glacier. By analyzing the climate records and glacier variation in the study area, it was concluded that higher temperatures led to the glacier retreat of the study area, but increasing rainfall to some extent inhibited glacier retreat. Topographic condition and the scale of glacier were key factors for glacier changes as well.
Vulnerability is a hot topic in natural disaster risk research. Vulnerability to storm surges not only depends on the distribution of population and socioeconomic values, but also the frequency and intensity of storm surges, as well as the coastal environment. This article systematically reviewed the progress of research on social vulnerability and physical vulnerability to storm surges, focusing mainly on the physical vulnerability of population, coastal defenses, and buildings. Uncertainties in vulnerability assessment were analyzed, and the application of storm surge vulnerability assessment in the field of rapid loss assessment, insurance, reinsurance, and disaster mitigation and adaptation were discussed. Finally, future avenues of storm surge vulnerability research were presented: (1) Quantitative storm surge vulnerability curves of typical exposure units need to be developed for application in the field of disaster insurance claims and loss assessment; (2) Standardized vulnerability assessment method of storm surge for typical exposure units needs to be established through field survey, physical experiments, and numerical simulation in response to the potential increase of catastrophe risk in the coastal area of China under global climate change.
Wandering rivers frequently occur in China, especially in northern China, with the wandering reach of the lower Yellow River as the most typical case. However, controversy concerning their channel pattern classification remains. While such rivers are widely regarded as wandering or wandering-braided channel in China, they are categorized as braiding rivers largely by the international geomorphological community. In this article, the wandering reach of the lower Yellow River is taken as an example and the evolutionary characteristics of channel morphology is summarized, focusing on the factors influenced the channel evolution in different periods. Based on the summary, a comparison is made between braiding and wandering rivers, including their channel definitions, morphological features, sediment characteristics, forming processes, and energy expenditure features. Especially, the wandering channel pattern mainly develops in a low energy slope environment that is far less than the minimum energy slope required for transporting sediment load. So it usually presents unstable features. The braided channel pattern can exist where river energy is lower or higher than the minimum energy slope. Therefore, it is essential to distinguish these two channel patterns. The article also discusses prospects for studies in the future and points out that focusing on the physical mechanisms for channel formation, developing and refining the energy theory, and examining the differences and similarities of wandering channel and braided channel systematically can help to solve the problem of classifiying wandering rivers.
Since the 1980s, international toponymy research by scholars including human geographers has shifted away from the traditional research paradigm using descriptive method to exploring origin, classification, dissemination, and diffusion of individual place names. The critical theory of humanities and social sciences gives birth to critical toponymy, and the new paradigm abandoned the pervious popular belief that place name is merely a neutral landmark for indicating geographic location. The new paradigm tends to focus on the dissection of the cultural, economic, and political motivations of naming or renaming, and attaches great importance to the critical interpretation of evolution of place-name landscape based on the perspectives of power competition and social relations. This critical turn provides an opportunity to better explain the tremendous changes in the place-name landscape in Chinese from the 1980s—an era that are characterized by the development of the market economy and rapid urbanization. This article first provides a comprehensive review of the main research content and development of critical toponymy in international academic circles with regard to economic, political, social, and administrative dimensions. It then elaborates on the progress of relevant research in Chinese, including name change of administrative division and streets in urban areas, commercialization of place name, competition for place name, place name and cultural identity, and so on. Last, the authors discuss the prospect of critical toponymy in Chinese in line with the socioeconomic development and take the Western critical toponymy as lessons dialectically. On the economic dimension, Chinese toponymic scholars need to pay greater attention to the economic benefit of coordinating the other dimensions; on the political and administrative dimensions, securing the naming right of disadvantaged groups should be of higher concern; with regard to the social aspect, the role of place name in cultural identity deserves great importance in the context of new urbanization.
