Spatial differentiation of natural and human factors in the land surface system of the Earth is the main concern of Geography. Given the complexity of the land surface system, different research methods should be applied to different issues concerning the system. Based on past geographical research, four paradigms were generalized, including geographical empirical paradigm, geographical positivist paradigm, geographical system science paradigm, and geographical big data paradigm. Appropriate paradigms should be employed for different scientific questions, and multiple paradigms should be applied to some complicated questions.
Industrialization, urbanization, agricultural modernization, informationization, and greenization (the so-called "Five Modernizations") are an important support for the modernization of the Chinese society, and therefore many scholars have conducted quantitative evaluation of the coordinated development of the "Five Modernizations". By examining the Chinese research on quantitative evaluation of the "Five Modernizations", this review obtained the following findings. First, whether using single indicators or comprehensive index, existing research differs on how to construct the index system due to different interpretations of the "Five Modernizations". Second, most studies choose the entropy method when calculating the indicator weights; fewer choose the subjective method such as the AHP; and very few choose the combination of subjective and objective methods. Third, the coordinated development evaluation methods focus primarily on coupling and coordinated coupling models, relation and forecasting methods, synchronization models based on deviating from the ideal spatial position, DEA dynamic efficiency and HR models, "development-difference-interaction level" models, and split models. Recently, systematic and mixed research methods are emerging and sophistication of these methods are improving. Fourth, spatial analysis methods of spatial pattern and spatial correlation are widely used in many studies. Methods such as track shift of spatial gravity, dynamic evolution of spatial pattern, and spatial trend analysis are gradually appeared in some recent articles. Fifth, most studies choose the methods of interpreting the main impacting factors and multiple linear regression models to analyze the influencing mechanisms of spatiotemporal patterns. Some recent studies use spatial regression models such as SLM, SEM, and GWR. Based on the literature review, we make some reflections on the research paradigm, index system, weight derivation, evaluation methods of coordination level, spatial analysis, and influencing mechanism interpretation. We recommend to strengthen the analysis of the internal driving mechanism and perspectives of evaluation, improve research on the evaluation index system and weighing method, adopt multiple evaluation methods of coordination degree, and promote the comprehensive application of spatial analysis technologies and integration of qualitative and quantitative interpretations.
Cities and their hinterlands are linked and interact with each other. Urban hinterland area provides important guarantee for the development of central city, and therefore accurate identification of urban hinterland area is beneficial for the assessment of urban development strength and potential. Since the emergence of hinterland theory at the end of the 19th century, urban hinterland study has been a hot topic in the fields of regional economics and urban geography. Meanwhile, under the background of market liberalization and increasing regional interdependencies, the spatial identification of urban hinterland area has become one of the key topics of urban geography study in China. This article systematically introduces the evolution process of research on urban hinterland area both in China and internationally in retrospect. The concept of hinterland mainly includes the following four aspects: (1) it represents fluidity radiation area with fluidity as the core concept;(2) it indicates city’s gravitation regions with gravity as the core concept; (3) it is a part of a center-hinterland system with the interactive relationship between central place and hinterlands as the core concept; and (4) one cannot separate a core city and its hinterland in a clear-cut manner. By comparing the concepts of urban hinterland area, this article summarizes the following: (1) urban hinterland research is changing from examining urban hinterland comprehensively to targeting more specific objects such as industrial, financial, and information hinterlands, which covers various aspects of urban hinterland; (2) object of identification has changed from the traditional city to urban agglomeration in response to the contemporary demand of urbanization; and (3) traditional quantitative identification method such as field spread model is revised according to various factors with the application of GIS technology, which enables visualization of the results. Finally, this article summarizes the research progress on quantitative identification of urban hinterland area, and points out the deficiencies existing in the current research and projects the research trends: (1) the object of quantitative identification will change from real cities to network cities. At the same time, hinterland will change from real hinterland to virtual hinterland; (2) the content of identification will focus more on ecological and cultural hinterlands since geographic research has increasingly taking on ecological and sociological perspectives; and (3) with regard to identification methods, non-parametric models will be widely used in future research.
As the key pigment for photosynthesis, chlorophyll is closely related to nitrogen, protein, moisture, and other biochemical parameters of vegetation. Chlorophyll is a good indicator for photosynthesis activity and physiological state of grasslands. Hyperspectral analysis is a powerful means for accurately retrieving grassland chlorophyll contents in large areas. Based on the existing methods for monitoring grassland chlorophyll contents, this article summarizes and groups such methods into two categories: empirical models of red edge position (REP) / spectral indices, and radiative transfer models. With statistical analysis of the relationships between chlorophyll contents and REP/ spectral indices, empirical models were extensively employed for estimating grassland chlorophyll contents. These models use simple parameters and the REP that is closely related to grassland chlorophyll contents can be conveniently calculated. Due to the diverse structural forms of the spectral indices and the complicated relationships between spectral indices and chlorophyll contents, accuracy of chlorophyll content estimation is still limited, although novel algorithms of REP calculation and, to a lesser extent, new spectral indices, have significantly improved the estimation accuracy of grassland chlorophyll contents. Based on the relationships of chlorophyll contents and radiation energy, radiative transfer models were founded. Multiple parameters are required in the models, which are highly sensitive to the scale of estimation, and these models need to be further improved. Currently there exist few studies on grassland chlorophyll content estimation and only very few models have been developed for grassland chlorophyll content estimation. Future research should focus on developing new indices or improving existing indices and determining appropriate parameters of radiative transfer models to achieve better results for grassland application. In addition, current studies are limited to leaf and canopy scale analyses, and therefore expanding grassland chlorophyll content estimation to the landscape scale will be an important and challenging task.
Forest landscape models simulate temporal change of forests using spatially referenced data across a broad spatial scale (landscape scale) generally larger than a single forest stand. Spatial interactions between forest stands are a key component of such models. These models can incorporate other spatiotemporal processes such as natural disturbances (e.g., wildfires, hurricanes, outbreaks of native and exotic invasive pests and diseases) and human influences (e.g., harvesting and commercial thinning, planting, fire suppression). The models are increasingly used as tools for studying forest management, ecological assessment, restoration planning, and examining the impact of climate change. In this article, we define forest landscape models and discuss their development, components, and types. We also review commonly used methods and approaches in modeling, their applications, and the strengths and limitations of different forest landscape models. New developments in computer sciences, geographic information systems (GIS), remote sensing technologies, decision-support systems, and geo-spatial statistics have provided opportunities for developing new generations of forest landscape models that are more valuable in ecological research, restoration planning, and resource management.
The new standard of city-size classification in China that divides all cities into five categories and seven subcategories, which was published in 2014, has gained popular attention. However,there have been various results of city-size classification due to different interpretations of the new standard. This article compares the new standard with the old standard and analyzes the city-size hierarchy of China in 2010 to evaluate the applicability and limitations of the new standard. The results show that the new standard has improved significantly over the old standard by changing the definition of population statistics, definition of urban space statistics, and the classification standard. Comparing the classification results based on the new and the old standards as well as other methods, the number of megacities and big cities reduced significantly while the number of small cities increased. The new result shows a clear pyramid structure of city sizes, which conforms to the central place theory and the rank-size rule. Thus, the new standard provides better guidelines to city management. According to the 6th census data in 2010, China has 12 megacities, 58 big cities, 93 medium-size cities, and 493 small cities. The majority of the higher rank cities are located in national-level urban agglomerations in southeastern China. However, the new standard also has some limitations. Urban resident population statistics that is a key in the new standard are often unavailable in non-census years, and the classification result is affected by adjustments of urban administrative boundaries. Further research on urban area identification and data sharing is urgently needed.
Stony deserts are widely distributed in the arid and extremely arid regions in China. However, an integrated physical regionalization of these stony deserts has not been carried out. Based on a comprehensive analysis of the relationship between the characteristics and formation mechanism of stony deserts, the main features of stony deserts can be summarized as follows: land surface is covered with gravels; surface layer has porous thin desert crust, below which red brown compact and gypsum layers are found. Vegetation mainly includes arid and extremely arid shrubs and semi-shrubs with low coverage. Stony deserts only exist in arid and extremely arid regions with aridity index greater than 4. Based on the regional differentiation of characteristics and formation conditions of stony deserts, this study selected indicators reflecting aridity and temperature, regional geology and geomorphology, and formation conditions and types of surface materials to classify the stony deserts into three first-level regions (temperate arid and extremely arid region, warm temperate arid and extremely arid region, and arid and extremely arid region in northern Tibetan Plateau); nine second-level regions (according to regional geological and topographical features), and 19 third-level regions (based on regional formation conditions and types of surface materials). Further division can be made based on regional differentiation of soils and vegetation.
Based on a geographical view of regional inter-connectedness, this study developed an analytical framework of provincial eco-compensation in China by industrial sectors. Input-output method was used to calculate the inter-provincial land resources consumption balance by industrial sectors and analyze inter-provincial industry eco-compensation based on the 2010 statistical data of China’s inter-provincial input-output data table. The results show that: (1) Farming, forestry, animal husbandry, and fishery are mostly the "occupied industries" where their ecological resources, land resources in particular, were used for the development of other industrial sectors. Therefore agriculture sector should receive eco-compensation. (2) Manufacturing industries "occupy" the ecological resources of other sectors and should pay for eco-compensation. (3) The construction sector, in the investment and consumption analyses, is primarily an "occupy" industry, but in the export analysis, there were great provincial differences. (4) The transportation and storage sector, in investment and consumption analyses, is mainly an "occupy" industry, but in the export analysis, there were also great provincial differences. (5) Wholesale and retail trade are mostly an "occupy" industry and should have the obligation to pay for eco-compensation. (6) Other services, in consumption analysis, are mostly an "occupy" industry but in the investment and export analyses, they are mostly an "occupied" industry where resources were taken by other industries and therefore should receive compensation. This paper puts forward policy recommendations for eco-compensation, including strengthening the legislation in industrial eco-compensation, improving taxation means in eco-compensation of industries, among others.
In Optically Stimulated Luminescence (OSL) dating, statistical age models used for equivalent dose (De) determination are probabilistic models constructed according to mathematical statistics. They are applied to distinguish De populations that are sedimentologically different or to determine a De value that represents the burial dose of a sample. Maximum likelihood estimation (MLE) method is routinely used to optimize parameters of an age model. In the present study, we used the Slice sampling algorithm to determine the parameters of age models. Slice sampling is a Markov chain Monte Carlo (MCMC) sampling method, which enables the sampling distributions of parameters to be obtained from the joint likelihood function that is determined by observations and the specified model. This study applied easily implemented and openly accessible numeric routines to performing the algorithm. We used artificial and measured datasets to check the reliability of the estimates. MCMC method is insensitive to the parameters’ initial states, and the standard errors (or confidence intervals) of parameters assessed using this method are more reliable compared to those based on the Fisher information matrix constructed through numerical differentiation. Our results indicate that the Slice sampling method provides an alternative for age model optimization. Slice sampling method generates an informative estimation for the results of MLE method in age model application.
Application of digital terrain analysis (DTA) relies heavily on the DTA-domain knowledge on the match between the chosen algorithm (and its parameter-settings) and the application context (such as target task, terrain condition of the study area, and DEM resolution)—the so-called application-matching knowledge. This type of knowledge has a direct impact on the quality of DTA modelling when users of DTA, especially non-expert users, do not have sufficient amount of such knowledge to support their DTA applications. Existing DTA-assisted tools often cannot use application-matching knowledge because this type of knowledge has not been formalized in DTA to be available for inference in these tools. This is mainly because this type of DTA knowledge is currently inaccurate and non-systematic, and often exists in documents for specific case studies, or as personal knowledge of domain experts. This situation makes the DTA modelling process difficult for users, especially for non-expert users. Case-based reasoning method that originated from artificial intelligence is appropriate for formalization and inference of non-systematic knowledge. In this article, we propose a case-based formalization and inference method for the application-matching knowledge in DTA. The specific design of the proposed case-based method can be divided into two parts: formalization of the application-matching knowledge, and inference method. The case of this knowledge consists of a series of indices to formalize the DTA application-matching knowledge and the corresponding similarity calculation methods for inference based on the case. To evaluate the performance of the proposed method, we implemented it in a software prototype of DTA modelling environment and then applied it to a DTA application of river network extraction. In the experiment we prepared 32 cases of river network extraction in the USA. The results of cross validation preliminarily show that the proposed case-based method is suitable for using the application-matching knowledge in DTA. It reduced the modelling burden greatly for users.
The airflow and sediment transport rate on the parabolic dune and the aeolian sediment flux profiles were examined in details in the southern Hobq desert in late April 2010 when the wind was strong and sediment movement was intense. The analyses show that 71%~91% sediments moved in the space between 0 and 0.10 m above surface. This confirms the results of previous research that blown sand activity occurs near bed. Due to the difference of wind velocity, underlying surface conditions, and slope profiles, sediment transport rate and relative sediment transport rate vary, so do the aeolian sediment flux profiles. At the measurement spots where wind velocity and sediment transport rate are small, such as the toe and the lower part of the windward slope, the aeolian sediment flux profiles vary considerably. Underlying surface condition is a vital factor influencing aeolian sediment flux profile. At the windward toe that suffers deflation, the gravelly surface is hard. This contributes to sediments’ saltaltion, so sediment transport rate is relatively high at the upper layer of the aeolian sediment flux profile. Along the windward slope, sediments move upward and have a lower saltation height. Therefore sediment transport is relatively high near surface. In contrast, sediments move downward at brink-line on the leeward slope with higher height and the trajectories deform, so the saltation height is higher. Affected by the difference of windward slope profile shape, the aeolian sediment flux profiles at the crest vary markedly among the measurement spots. In spite of the variation of the aeolian sediment flux profiles, they can still be well described by the exponential decay law at the windward slope and crest. In the equation Q=aexp(-z/b), the coefficient a has an apparent power function correlation with sediment transport rate and increases simultaneously with wind velocity, but there is no clear correlation between them. The coefficient b has no significant correlation with these two factors. At the brink-line, the profiles were segmented at the 0.10 m height: the profiles of near surface follow exponential decay while the upper layers obey power function.
Passenger and freight flow distribution and dynamic change are the characteristic index of regional transport patterns. This article analyzes passenger and freight flow rank-size distribution and regional patterns between 1980 and 2010 in the Pearl River Delta (PRD) area using the rank-size distribution theory. The results show that: passenger and freight flow q values were greater than 1, in line with rank-size distribution, but the distribution was more in line with the size of the passenger rank-size distribution. Passenger q value decreased and then increased, showing non-equilibrium-relative equilibrium-disequilibrium evolution characteristics. The q values of freight flow decreased, showing non-equilibrium-relatively balanced evolution characteristics. With regard to the spatial pattern, passenger flow shifted from a single center to multi-centers, with a macro scale “point shaft” and mesa-scale “hub and spoke” regional system. Freight flow showed a long-term pattern of monocytes leading to the macro and mesa scale “hub and spoke” system. Convergence of industrial structure in the PRD, light industry-dominated industrial structure, coupled with the single center (Guangzhou) radial transport network determined the spatial pattern of monocyte freight flow.
With rapid urbanization, huge populations concentrate in cities, greatly increasing the environmental pressure of urban systems. Improving convenience of travel and at the same time reducing its negative effects on the environment, such as mitigating carbon emissions, is the key objective of present and future sustainable urban transportation development and important indicators of urban transportation efficiency. This research adopted a multi-objective evaluation method to evaluate transportation efficiency, including quantitative models for estimating carbon emission and convenience of travel and integrated methods of carbon emission and transport convenience. The six central urban districts in Beijing were chosen as our study area to test the evaluation method and explore mechanisms of transportation efficiency. The results show that transportation efficiency in Beijing differs between the central city and the outside areas. The efficiency is lower outside the 5th ring road, and higher inside the 3rd ring road. Especially, there are several centers of high and low transportation efficiency areas. The high efficiency centers are located in (1) the Gongzhufen-Wukesong area around the west 3rd and 4th ring roads; (2) the Anzhen Bridge area near the north 3rd ring road; and (3) the Sanlitun area near the east 3rd ring road. The low efficiency centers are located in the suburban areas, such as along the northwest 6th ring road, some areas between the 5th and 6th ring road in the southwest, and the Changying area outside the 5th ring road in the east. Besides, the spatial differences of transportation efficiency in Beijing have a close relationship with the geographic context. High carbon emission is the main cause of low transportation efficiency; this is particularly true in the areas where luxury-villas are located, and where public transportation service provision is insufficient. High proportion of car usage and long commuting distance are the main causes of high carbon emission. In the future, the construction of public transportation, especially the optimization of the subway system development, will improve the spatial distribution of transportation efficiency.
In cities there is a high concentration of social and economic activities at subway stations. Different types of subway stations have different functions, as reflected in their regional characteristics, traffic function, and land use. Meaningful station classification helps to understand urban functional partition and evaluate rail transportation infrastructure development. Based on the usage data of subway passes, this study classified the subway stations with time series clustering. The result shows that (1) subway station passenger flows have clear temporal and spatial differences. It reflects the temporal and spatial differences of urban functional partitions; (2) this study uses a time series clustering method. By considering passenger flow characteristics, subway stations can be divided into residential-oriented stations, employment-oriented stations, spatial mismatched stations, mixed mainly residential-oriented stations, mixed mainly employment-oriented stations, mixed type stations, commerce- and attraction-oriented stations, and other stations; (3) Using traffic data at subway stations is an effective way to compare spatial behavior and physical space.
