Table of Content

    25 March 2015, Volume 34 Issue 3 Previous Issue    Next Issue
    Urban Agglomeration
    Function orientation and coordinating development of subregions within the Jing-Jin-Ji Urban Agglomeration
    Dadao LU
    2015, 34 (3):  265-270.  doi: 10.11820/dlkxjz.2015.03.001
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    In this article, we examine the economic linkage and competition among cities in the great metropolitan region of Jing-Jin-Ji. Specifically we demonstrate that Beijing, Tianjin and Hebei Province have developed their unique industry structures and gained corresponding comparative advantages since the beginning of the reform and opening up. Accordingly, we propose the function orientation of Beijing, Tianjin and Hebei Province based on their industrial characteristics and the principle of strategic interest of the country.

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    The nature of urban agglomeration space and the construction of Zhongyuan Urban Agglomeration
    Changhong MIAO, Zhiqiang HU
    2015, 34 (3):  271-279.  doi: 10.11820/dlkxjz.2015.03.002
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    Regional research is one of the core topics of Geography. In the development process of geography, the debate on region is broadly divided into two categories—territorial space and network space—and there has been a trend of change from one-dimensional space to multidimensional space. Regions were often considered as a space that has one or more common features among its components, and a region is bounded, closed. With the advancement of globalization and information society, regional relations continue to strengthen. Therefore some scholars put forward the concept of network space, which highlights the interactions and relationships between regions. A network space is open, dynamic, and with uncertain boundaries. Increasingly, the single dimension to regional definition was viewed as biased. The space of Chinese urban agglomerations is a new type of region. It has multiple properties, not only as a territorial space and network space, but also as the place where space is produced and created. There is a great difference in perspective between territorial space and network space. Attention of regional research is shifting from production in space to the production of space itself. The production of space cannot take place without the operation of power, and space is also the product of the discourse construction. Based on the debates of a region as a territorial space, or a network space, and the production of space, this article discusses the debates on the concepts and construction of Chinese urban agglomerations. Taking the Zhongyuan urban agglomeration as an example, this research examined some practical problems in its construction, and addressed the vital question: What is an urban agglomeration and its nature? In order to coordinate and combine the varied dimensions on Chinese urban agglomeration, we put forward a TPSNF framework to integrate the five dimensions for defining urban agglomeration: territory, place, scale, network, and function and proposed some key research focus in the future.

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    Delineating the scope of urban agglomerations based upon the Pole-Axis theory
    Xiaolu GAO, Zening XU, Fangqu NIU
    2015, 34 (3):  280-289.  doi: 10.11820/dlkxjz.2015.03.003
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    Delineating the scope of urban agglomerations is a basic condition for understanding the evolution of cities and regions and for developing strategies and planning of urban agglomerations. At present, the scope of urban agglomerations in China are mainly decided based upon analyses of center cities and their connections with other cities by viewing them as separate points, but there is few consensus on how to define the spatial boundary of urban agglomerations other than using the jurisdiction border of the cities. In practice, there is a tendency to take urban agglomeration as a policy tool for raising the importance of certain areas and promoting regional development. As a result, the number and scope of urban agglomerations have been exaggerated. In order to solve these problems, in this article a methodology for delineating the scope of urban agglomerations is discussed from an economic geographic perspective based on the 'Pole-Axis Theory'. A four-step process was proposed: (1) to make judgment of the existence of central cities; (2) to examine the cities' rank system and the resources and environment base of the region to see if an urban agglomeration can be sustained; (3) to analyze the social and economic connections between central cities and other cities in the region; (4) to evaluate the development level of urban agglomerations with the scale of 'Pole-Axis Theory'. A case study is conducted in the Beijing-Tianjin-Hebei Region, and a comparison is made about the formation and development of the five main urban agglomerations in the Beijing-Tianjin-Hebei, Yangtze River Delta, Perl River Delta, Middle Yangtze River, and Chengdu-Chongqing regions.

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    Classification of China's urban agglomerations
    Jinchuan HUANG, Shouqiang CHEN
    2015, 34 (3):  290-301.  doi: 10.11820/dlkxjz.2015.03.004
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    Urban agglomeration is an important carrier of China's new urbanization strategy, but also a new geographical unit for participating in global competition and international division of labor. At present, the mode of China's regional spatial governance is undergoing a major shift from the original spatial split according to the administrative divisions to govern in accordance with the type of area. Based on the significant extension of the characteristics of urban agglomerations, we divide the 23 Chinese urban agglomerations at four levels and analyze the spatial variation, aiming to provide a scientific basis for the implementation of China's urban agglomerations spatial pattern optimization and planning. First, the 23 areas are divided into national, regional, sub-regional and local levels of urban agglomerations with reference to the development status of more mature urban agglomerations worldwide, resulting in a "3-5-6-9" pyramid structure for the four levels. Then, based on the five essential characteristics of urban agglomerations, we build an index system for the classification of urban agglomerations that consists of 10 factors and 22 indicators, and a Q-type cluster analysis is employed to quantitatively group five kinds of the urban agglomerations: mature export-oriented type, dual-core catch-up type, environment-friendly type, single nuclear radiation type, and inland extensive type. Finally, by synthesizing the classification results of different levels and quantitative clustering, China's urban agglomerations are divided into 10 subgenera: National mature export-oriented genre, national dual-core catch-up genre, regional dual-core catch-up genre, sub-regional environment-friendly genre, local environment-friendly genre, regional single nuclear radiation genre, local single nuclear radiation genre, regional inland extensive genre, subregional inland extensive genre, and local inland extensive genre.

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    Development strategy of the Pearl River Delta Urban Agglomeration under the current socioeconomic situation
    Chunshan ZHOU, Wanfu JIN, Chenyi SHI
    2015, 34 (3):  302-312.  doi: 10.11820/dlkxjz.2015.03.005
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    Recently, domestic and international economic situations have changed significantly. The Pearl River Delta (PRD) area in this period of transition is facing unprecedented challenges, and development strategies for the PRD need to be reconsidered. This article reviews the development process of the PRD and analyzes its development situation. Then, the PRD is compared with the urban agglomerations at home and abroad. The results show that in 2000-2013, the economic development and the population growth of the PRD have slowed down; the disparity of regional economic development has gradually narrowed; the industrial development tends to be more advanced; and economic globalization has decreased. At present, the level of development and competitiveness of the PRD is much weaker than world-class urban agglomerations. Compared with the Yangtze River Delta and the Beijing-Tianjin-Hebei Uban Agglomerations, the speed of development in the Pearl River Delta area has decreased. The PRD should attach greater importance to technology innovation of industries, intensification of land-use, innovation of population policy, regional cooperation, and humanistic concerns under the new conditions.

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    Review of range recognition research on urban agglomerations
    Shouqiang CHEN, Jinchuan HUANG
    2015, 34 (3):  313-320.  doi: 10.11820/dlkxjz.2015.03.006
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    Urban agglomeration is an important form of regionalized city development, but also an iconic product of advanced regional industrialization and urbanization. Based on the diverse conceptual evolution processes of urban agglomeration and focusing on the technical method s and approaches for the identification of urban agglomerations, this article reviews in detail the research progress of the range identification of urban agglomeration growth. It concludes that the main reasons that academia seldom reach consensus on the spatial extent of urban agglomeration are as follows: there exist significant differences in the understanding of the essence of the concept, definition, smallest unit of analysis, and choice of identification methods of urban agglomeration. This article clarifies the main research methods of range identification of urban agglomeration: (1) the traditional socioeconomic index method represented by defining metropolitan areas in the United States has broad influence and has set the fundamentals of range identification of urban agglomerations in the West; (2) applying gravity models for the recognition of the scope of influence of central cities has become the main method for urban agglomeration range identification research in China; (3) using spatial analysis technology in GIS as means, integrated simulation methods incorporating integrated indicators and modeling methods represent the future trend of study on the recognition and identification of urban agglomeration growth.

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    Theoretical Model and GIS Application
    Simplicity, complexity, and mathematical modeling of geographical distributions
    Yanguang CHEN
    2015, 34 (3):  321-329.  doi: 10.11820/dlkxjz.2015.03.007
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    Because of quantitative revolution, geography evolved from a discipline of spatial description into a science of distributions. Accordingly, qualitative methods were replaced by the integrated methods of quantitative analysis and qualitative analysis. One of the important approaches to spatial analysis is to characterize geographical distributions. Geographical distributions fall into spatial distributions and size distributions, both of which can be divided into simple distributions and complex distributions. A simple distribution has a characteristic scale (represented by a characteristic length), while a complex distribution has no characteristic scale but bears a property of scaling invariance (represented by a scaling exponent). The key step of studying a simple distribution is to find its characteristic scale, while the basic way of research for a complex distribution is to make a scaling analysis. For simple distributions, traditional methods based on advanced mathematics are effective, but for complex distributions, the old-fashioned mathematical tools are ineffective. However, due to the lack of understanding of characteristic scale and scaling, geographers often failed to distinguish between simple distributions and complex distributions. As a result, many complex systems such as cities and systems of cities were mistaken for simple systems. Consequently, geography did not succeed in theorization in the 1960s-1970s after quantification in the 1950s-1960s. Geographical distributions can be mathematically abstracted as probability distributions. For a simple distribution, its characteristic scale can be determined. A typical characteristic scale is a mean (average value). Based on means, we can compute a variance and a covariance. Thus we have a clear probability structure comprising means, variances, and covariances, which explain the pattern of the geographical system and predict its process of evolution. In the case of a complex distribution, an effective mean cannot be determined, and thus little is known about its probability structure. In this situation, characteristic scale analysis should be substituted with scaling analysis. Quantitative methods of scaling analysis have emerged from interdisciplinary studies. A new integrated theory based on concepts from fractals, allometry, and complex network has been developing for geographical modeling and analysis.

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    Orginal Article
    A global inventory of lunar craters: identification, classification, and distribution
    Jiao WANG, Weiming CHENG, Chenghu ZHOU
    2015, 34 (3):  330.  doi: 10.11820/dlkxjz.2015.03.008
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    The most widespread geomorphic units on lunar surface are craters. In this article, we use a remote sensing image and DEM model from the Cang'E-1 satellite as data source to study craters on the lunar surface. First, an integrated procedure that uses a remote sensing image, DEM and its derived products (slope, curvature) to extract the edifice of craters is applied. At a scale of 1: 2500000 edifice boundaries are manually defined by searching for breaks in slope around the base and there are a total of 106030 impact craters identified. Then we present two methods to evaluate the extraction accuracy and cumulative crater frequency. The result shows that the extraction error is less than 12 percent and the cumulative crater frequency curves from both sets of data obtained through these two methods are similar. Second, all the craters are divided into six groups including the ghost, walled plain, ring plain, crater plain, bowl-shaped, and dimple craters based on previous studies. A corresponding interpretation symbol database is established to illustrate the appearance of craters on a digital image. Finally, some statistical data on different types of craters across the lunar surface are generated. Characteristics such as number, density, and spatial distribution are calculated in ArcGIS and SPSS. We find that the bowl-shaped craters are the major type of all the craters and there is a strong inverse correlation between the number of craters and their diameter. The data provided herein is by far the most comprehensive lunar craters data so that it offers an opportunity to systematically study the impact mechanisms, impact effects, and evolutionary history of craters on lunar surface.

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    Hydrology andWater Resource
    Review on atmospheric water vapor isotopic observation and research: theory, method and modeling
    Jingfeng LIU, Minghu DING, Cunde XIAO
    2015, 34 (3):  340-353.  doi: 10.11820/dlkxjz.2015.03.009
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    Stable isotopes of atmospheric water vapor have been used as informational tracer in understanding global earth surface processes and hydrological cycle. Based on the physical process of water transportation, this article introduces the theoretical basis of water vapor isotopic fractionation, including equilibrant and non-equilibrant fractionation such as evaporation process, transportation, and considerations, and reviews traditional measurement methods and new techniques such as laser spectrometer and satellite remote sensing infrared spectrometer. It shows that real-time and remote sensing observations have become useful methods for water vapor isotope research. The paper also summarizes the main progresses on water vapor isotopic theory and the general/regional climate models enabled with isotopic module. Iso-GCM/RCM has advantages in global and regional climate process research and environmental information reconstruction, and will be widely used in future research. Emerging focuses of atmospheric isotope research are high spatiotemporal resolution measurement and application of new indices such as 17O-excess and Iso-GCM/RCM.

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    Spatiotemporal variability of extreme precipitation in north and south of the Qinling-Huaihe region and influencing factors during 1960-2013
    Shuangshuang LI, Saini YANG, Xianfeng LIU
    2015, 34 (3):  354-363.  doi: 10.11820/dlkxjz.2015.03.010
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    Based on the monthly precipitation of a 0.5°×0.5° grid dataset and the daily precipitation observations of 135 meteorological stations released by the National Meteorological Information Center of China, this study analyzed the spatiotemporal variation of extreme precipitation in north and south of the Qinling-Huaihe region during 1960-2013, using the methods of trend analysis, Sen+Mann-Kendall model, and correlation analysis. More specifically, we analyzed the relationship between ENSO and the observed extreme precipitation. The results are as follows: (1) the precipitation showed an increasing trend in the lower reach of the Yangtze River and a decreasing tendency in the other regions; (2) extreme precipitation analysis indicates a declining trend in rainy days and an increasing trend in precipitation intensity. The number of continuous drought events increased. Spatially, the regions with increasing intensity of extreme precipitation were mainly distributed in the Qinling-Bashan Mountains and the lower reaches of the Yangtze River and Yellow River, whereas there were more drought events in the Guanzhong Plain, Wushan Mountains, and Sichuan Basin; (3) Extreme precipitation had a close relationship with ENSO in the study region. In El Niño years, more precipitation was found in the spring but there was less precipitation in the summer and the whole year. In La Niña years, there was less precipitation in the spring and more precipitation in the autumn and the whole year. The responses of extreme precipitation events to El Niño exhibited spatial differences. Most of the regions with decreasing extreme precipitation in El Niño years were distributed in the lower reach of the Yellow River, the Guanzhong Plain and Qinling-Bashan Mountains, as well as the Sichuan Basin, while the region with increasing extreme precipitation was the Huaihe Plain. The lower reach of the Yangtze River and the Wushan Mountains showed no clear response to ENSO.

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    Runoff generation in the headwater of Amu Darya, Central Asia
    Xiaolei WANG, Lin SUN, Yiqing ZHANG, Yi LUO
    2015, 34 (3):  364-372.  doi: 10.11820/dlkxjz.2015.03.011
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    Amu Darya is the largest river in Central Asia that provides water resources to downstream water users and flows into the Aral Sea. Runoff of the Amu Darya River is dominated by snowmelt and glacier melt originating from the alpines. Quantification of snowmelt and glacier melt contribution to the runoff is important for understanding the dynamic characteristics of the streamflow. This study investigates the glacier and snow melt processes in the headwaters of Amu Darya by using a glacier-enhanced SWAT model. The simulations were run through 1951 to 2005. The results indicate that the SWAT-RSG model could well estimate the monthly streamflow process of the Amu Darya River Basin, and the efficiency coefficient and absolute value of PBIAS in the calibration period (1961-1975) and validation period (1976-1985) could be higher than 0.6 and lower than 25%, respectively. Snowmelt and glacier melt contributed 67% and 15% of the annual runoff. The Amu Darya River is mainly supplied by melting high-mountain snow and glaciers, which was concentrated in March to July and June to September, respectively. Owning to the combined effect of rainfall, snowmelt, and glacier melt, the runoff is concentrated in April to September, accounting for 83% to the total runoff, and the peak occurred in July. The results of Mann-Kendall trend analysis indicate that precipitation showed a significant decreasing trend and temperature showed a significant increasing trend from 1951 to 2005, and experienced a sudden jump in 1995. Due to the change of temperature and precipitation, snowmelt showed a decreasing trend and the value during 1996 to 2005 (Period Ⅱ) was 20% lower compared to that in 1951 to 1995 (Period Ⅰ). Due to the shrink of glacier area and reduction of precipitation, glacier melt showed a non-significant decreasing trend between 1951 and 2005 and the annual glacier melt in Period Ⅱ was 4% less than that in Period Ⅰ. Despite that the rainfall had slightly increased, the rain runoff was reduced by 35% as a result of the increased evapotranspiration. Consequently, the streamflow was reduced by about 260 million m3 each year from 1951 to 2005. The runoff showed a 21% reduction from Period Ⅰ to Period Ⅱ. The study of runoff generation characteristics in the headwaters of the Amu Darya River can provide references for the water resource management in the Amu Darya River Basin and Central Asia.

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    Entropy weight-based water security assessment in Asia-Pacific
    Hong JIANG, Xiaoliu YANG
    2015, 34 (3):  373-380.  doi: 10.11820/dlkxjz.2015.03.012
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    In this study the entropy method was adopted to calculate the indicator weights of the water security indicator system and the water security status of the 47 countries in the Asia-Pacific region were then assessed. National water security consists of 5 dimensions—household water security, economic water security, urban water security, environmental water security, and resilience to water-related disasters. The regional disparity of household water security is most significant, while the minimum value of regional disparity is found in resilience to water-related disasters. Regional economic water security is relatively satisfactory in Asia-Pacific; however, compared to other dimensions, resilience to water-related disasters is less satisfactory. The assessment reveals the actual water security status of countries and the result indicates that Australia, New-Zealand, and Malaysia are the most favorable countries in terms of national water security, but Kiribati is the worst country; countries in East Asia and the Pacific are in a much better condition than those in South Asia, Southeast Asia, and Central-West Asia. The overall water security situation in Asia and the Pacific region urgently needs improvement.

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    Renewal rate of groundwater in the Baiyangdian Lake Basin
    Ruiqiang YUAN, Xiting LONG, Peng WANG, Shiqin WANG, Xianfang SONG
    2015, 34 (3):  381-388.  doi: 10.11820/dlkxjz.2015.03.013
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    Human activities, such as water storage in reservoirs and pumping for irrigation, reduce stream flows and deplete unconfined aquifer in the plain area of the Baiyangdian Lake Basin. Without recharges from rivers and groundwater, the Baiyangdian Lake faces the risk of drying up. Considering the impacts of the Baiyangdian Lake on the local environment, biodiversity, and climate, many projects of water transfer for the sustainability of the lake were implemented. However, the result are unsatisfactory due to considerable leakages in the lake. In order to preserve the lake, sustainable groundwater use should be achieved and therefore, it is necessary to study the renewal rate of unconfined groundwater. In this study groundwater was surveyed on the plain area of the Baiyangdian Lake Basin in 2009. thirty six samples from groundwater and surface water were collected for measuring the content of tritium. Tritium content in precipitation since the mid-1950s was rebuilt by comparing the results from linear interpolation, Wu's method and Lian's method. Renewal rate of groundwater in the plain area was estimated based on the tritium data and the well-mixed model. Results show that leakage of the lake slightly increased tritium content in the ambient groundwater. Generally, the renewal rate of unconfined groundwater decreased from 15.0 %/a to 4.0 %/a between the mountain area and the lake. Alluvial fans are the main recharge area with an average renewal rate of 9.8 %/a. The renewal rate dropped to 4.4 %/a in the alluvial plain. We recommend that groundwater development should be restricted in the alluvial plain to recover the renewal rate of unconfined groundwater. Although such recovery may take a long time to occur, it is believed that recharging the lake by shallow groundwater is the only way to maintain a sustainable lake.

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    Research progress on stochastic soil moisture dynamic model
    Jian HU, Yihe LÜ
    2015, 34 (3):  389-400.  doi: 10.11820/dlkxjz.2015.03.014
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    As an important component of the earth surface system and the core of hydrological cycle, soil water controls the most basic terrestrial ecosystem patterns and processes, which is key for the healthy operation of the terrestrial ecosystem. Soil moisture dynamics is an indispensable part of the research on the interactions and feedbacks between hydrological processes and terrestrial ecosystem processes, which is the result of non-linear interactions among a series of hydrological, climatic, and ecological processes. Consequently, soil moisture dynamics needs to be studied by stochastic methods, which can reasonably describe the characteristics of soil moisture dynamics including the pulse, erratic, and random processes. In this article, we systematically review the development of stochastic modeling of soil water content based on the principle of soil water balance, and focus on the classification and application of these models. This review could supply some useful reference for quantitative studies of stochastic soil moisture dynamic processes and be beneficial to the research on ecohydrology in China. This review also could promote a better understanding of interactions between hydrological cycle and the terrestrial ecosystem, and ultimately contribute to the knowledge base on the sustainable management of water resources and ecosystems.

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