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    25 January 2014, Volume 33 Issue 1 Previous Issue    Next Issue
    Invited Paper
    Changing characteristics of extreme climate events during past 2000 years in China
    ZHENG Jingyun, HAO Zhixin, FANG Xiuqi, GE Quansheng
    2014, 33 (1):  3-12.  doi: 10.11820/dlkxjz.2014.01.001
    Abstract ( 974 )   PDF (4486KB) ( 1983 )   Save
    In the current research on climate changes it is a hot topic to study the changes of extreme climatic events during historical periods. In this paper, based on the reconstructions from multiple proxy types including historical documents, tree-rings, ice cores and lake sediments in the published literature of the recent 20 years, we summarized the characteristics of changes of extreme climate events during the past 2000 years in China. The analysis shows that: (1) During the cold periods of 1500-1900 and 220-580, there appeared extremely cold winters that were even colder than the cold winters in the years after 1950, and there appeared hot summers with daily highest temperature exceeding record high of the years in the 20th century as well. In the past 1600 years, the cold summer events in Northeast of China mainly occurred during the period of 1400-1900. (2) In the eastern monsoon region of China, the extreme drought events prevailed during the periods of 301-400, 751-800, 1051-1150, 1501-1550 and 1601-1650, the extreme flood events often occurred during the periods of 101-150, 251-300, 951-1000, 1701-1750, 1801-1850 and 1901-1950, and for the period of 1551-1600, coexisting extreme drought and extreme flood events occurred most frequently. The frequency of persistent extreme drought was higher during the 7th-8th century, 12th-14th century and late-15th century to mid-17th century; the frequency of sustaining extreme flood was higher during the 10th-11th century and after the mid-17th century. The time intervals of extreme drought/flood events are different in North China, Yangtze and Huaihe River Valley and south of Yangtze River. In addition, the notable extreme drought events, such as "Chong Zhen Drought" in the Ming Dynasty, and "Ding Wu Famine" in the Qing Dynasty, were recognized. (3) In the arid region of Northwest China, the extreme drought events mainly occurred during the periods of 1471-1520, 1581-1650, 1711-1760, 1811-1860 and 1921-1970. 1710s was the most severe drought decade during the past 1000 years. However, due to the very limited climate proxy data for this region, the primary characteristics of complete change process of the extreme events were difficult to evaluate. (4) Although drought frequently occurred in southwest of China during the early 21th century, the extreme drought events as severe as the one in Sichuan and Chongqing in 2006 occurred many times during the historical periods.
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    Special Column: Annal Symposium on Geomorphology and Quaternary 2013
    Grain-size features of Quaternary red earth in Dongting Lake Area and their paleoenvironmental significance
    ZHU Lidong, GU Xiji, YE Wei, LI Fengquan, JIN Lidan, CHEN Qu, ZHAN Wenjuan, LIU Mingyu
    2014, 33 (1):  13-22.  doi: 10.11820/dlkxjz.2014.01.002
    Abstract ( 622 )   PDF (6226KB) ( 1138 )   Save
    Dongting Lake Area is a semi-closed basin opening toward the north. In this area, alluvial and lacustrine sediments mainly developed in fluvial plain, low level terrace of the rivers and modern lakebed, and Quaternary red earth is widespread in low mountains, hills and hillock. Scholars paid very little attention to the red earth in this area over a long period of time in the past. In order to reveal the genesis of the Quaternary red earth in Dongting Lake Area and its preliminary climatic implications, we did a series of work. The detailed field investigation has shown that there are several types of Quaternary red earth in Dongting Lake Area, and the major type is the red earth with homogenous structure without gravel. The intact stratigraphic profile consists of the lower reticulate red earth layer or reticulate yellow brown earth layer and the upper homogeneous red earth layer or yellow brown earth layer. Ten profiles of this type of Quaternary red earth and 122 samples were collected, and their grain-size was tested by using laser particle size analyzer Malvern 2000, a product of Malvern of the UK. The results showed that: (1) Silt (4~63 μm) is the major type of particle in all samples; clay (<4 μm) is the second major type; sand accounts for the smallest portion. Aeolian particle (10~50 μm) is the dominant particle, and the mean content ranges from 33.23% to 42.23%. These features are similar to those of the loess, Xiashu loess and aeolian red earth, but quite different from fluvial red earth from Xiangjiang Rriver terrace and the residual red earth formed with the rock weathering, indicating that aeolian red earth exists on the hilly land of the west, south and east sides of Dongting Lake Area and they all belong to aggradation red earth in Mid-subtropics. (2) All the samples can be separated into four categories: vermicular red earth, homogeneous red earth, reticulate yellow-brown earth and yellow-brown earth. In terms of grain size composition, their clay contents have a ranking order of vermicular red earth >homogeneous red earth >reticulate yellow-brown earth >yellow-brown earth, while their silt contents show an opposite ranking order. Combined with other information extracted from grain size parameters, we can speculate that sedimentation significantly strengthened during the period of yellow-brown earth, so the sediments become coarser and well sorted. However, in the period of vermicular red earth, sedimentation weakens and weathering strengthens, fine particle content increases, and the red earth are poorly sorted. This probably reflects the environmental change process in which winter monsoon strengthens and weathering weakens from the mid-Pleistocene to the late Pleistocene around Dongting Lake Area. (3) Along with the direction of the winter monsoon, the average particle size and median size (φ value) of the red earth become bigger (become smaller) southwards, but the percentages of aeolian component (10~63 μm) decrease while that of the<2 μm component increase slightly. These trend, therefore, provide aeolian evidence for the Quaternary aggradation red earth sediments and suggests that the intensity of weathering enhances southwards in the Dongting Lake Area.
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    Methodology on hierarchical classification of multi-scale digital geomorphology
    CHENG Weiming, ZHOU Chenghu
    2014, 33 (1):  23-33.  doi: 10.11820/dlkxjz.2014.01.003
    Abstract ( 842 )   PDF (1516KB) ( 1255 )   Save
    In this paper, based on classification method and legend layout of published geomorphological maps of the nation at different levels and different scales and the hierarchical classification method for the digital geomorphology of China with a scale of 1:1000000, we proposed a hierarchical land classification system with the indicators in five major categories. The indicators include basic landform form, morphological characteristics of geomorphological types (including morphological assembly, micro-landform morphological entities, slope form characteristics of landform surface), basic genesis and main genetic action ways, materials and lithology, formation age or period of geomorphological types, which all combined are a comprehensive presentation of geomorphological characteristics. These indicators can be divided into three categories and nine levels: landform superclass (sub-superclass), landform class (sub-class) and landform type (sub-type), at the nine levels, such as macro morphology, terrain characteristics, main genetic condition, main genetic action ways, morphological assembly, micro-landform morphological entity, slope characteristics, material and lithology and landform formation age. The geomorphological characteristics can be expressed by means of not only continuous polygons addressing morpho-genetic types, but also discrete points, lines and polygons addressing morpho-structural types. The morpho-genetic and morpho-structural geomorphological types can be exchanged for each other based on mapping scales. Based on geomorphological characteristics, the indicators of former four grades can be mapped for 1: 4000000 geomorphological maps, and former five grades for 1:1000000 geomorphological maps, and former seven grades for 1:500000 geomorphological maps. As to 1:250000 and 1:50000 geomorphological maps, parts of morpho-structural geomorphological types can be converted to morpho-genetic geomorphological types, slope form characteristics, terrain slope position, material and lithology and formation age of micro-landforms can be highlighted in order to realize the expression for detailed geomorphological types. As to China's offshore and adjacent ocean topography and geomorphology, four hierarchical geomorphological types can be classified in terms of spatial position, water dynamic condition (ocean water depth and slope characteristics), and lithosphere types and depth change. Form-genetic types can be expressed by means of the former three classes and form-structural types can be expressed by means of fourth class.
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    Spatial variations of gravel sediment granularities and their causes in Ganxi Stream of Zhangjiajie
    WANG Suiji, YAN Yunxia, YAN Ming, HE Li, FANG Haiyan, WANG Yanjun
    2014, 33 (1):  34-41.  doi: 10.11820/dlkxjz.2014.01.004
    Abstract ( 585 )   PDF (6041KB) ( 1319 )   Save
    Cumulative probability curve of particle granularities is one of the methods to study the sediments. However, the sediments in the studies were mainly sands/sandstone and silts/siltstone, and granule at most in the past. Recently the rivers with large gravel bed materials including pebbles, cobbles and boulders in mountainous regions have been studied more and more. But the distribution pattern of the granularities of coarse gravels such as pebbles, cobbles and boulders has yet to be well studied. In this study, taking the modern gravel sediments of the mountainous Ganxi Stream in Zhangjiajie scenic spot as an example, the cumulative probability curves of gravel granularity were studied for the sampling on the channel bed, mid-channel bar and channel bank. The granularities of these gravel sediments ranged from 23 mm to 663 mm, with most of them being pebbles, cobbles and boulders. The results showed that these fluvial gravel sediments followed a statistical pattern very well and exhibited a spatial variation trend that reflected the river flow hydrodynamics. For each sample the gravel granularities could be expressed by a cumulative probability curve clearly with two or three sections. The gravels in different sections reflected different fluvial power in different flooding stages. Granularity parameters showed that the gravel sediments have higher degree of sortability and sphericity. The median diameters of the gravels on channel bed have a decreasing trend downstream, reflecting the decrease of stream power in that direction. The reason for the various kurtosis of the gravels is that the blocks that fell to the river from the cliffs of "the sandstone forest" had not been modified sufficiently by the stream flow. The fine gravels intercepted in the apertures of cobbles and boulders in low flooding stages resulted in negative deflection of granularity distribution of the channel gravel sediments. By comparing the sphericity among different lithological gravels one can find that the gravels composed of carbonate rocks have the highest level of sphericity while the gravels composed of quartzose sandstone have lower level of sphericity. This phenomenon suggests that the quartzose sandstone gravels have higher ability to resist the flow erosion while the carbonate rock gravels have lower ability. This work is a useful attempt to study the distribution pattern of fluvial gravels including boulders, and has a revelatory significance to the quantitative studies of the coarse gravel sediments such as cobbles and boulders in mountainous fluvial rivers with steep gradients.
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    Morphological characteristics and developmental stages of loess tablelands based on DEM
    TONG Chiming, ZHOU Chenghu, CHENG Weiming, ZHANG Wenjie, WANG Jiao, LIU Haijiang
    2014, 33 (1):  42-49.  doi: 10.11820/dlkxjz.2014.01.005
    Abstract ( 684 )   PDF (2500KB) ( 975 )   Save
    DEM-based terrain analysis has been widely used in geomorphology. Currently most researches are qualitative or semi-quantitative, whereas quantitative analyses of large areas based on a variety of parameters are few and far between, and most studies use artificial field measurement with a small scale in the aspect of the relative age of the landscape entity. So, in this article, by using 30 m ASTER-GDEM, GIS and digital terrain analysis method, we extracted morphological parameters of a wide range of the areas of loess tablelands and determined their relative ages. We tried to provide basic knowledge of multi scale representation of the loess tablelands and fine landforms, achieved quantitative descriptions of the similarities and differences among the loess tablelands, and calibrated their developmental stages. First, we extracted positive landforms less than 15° in the Loess Plateau. Then, we acquired the top surface of the loess tableland using two parameters: gradient and waviness. We determined 1106 loess tablelands based on the subtraction between positive landform layer and the top surface layer. We selected 106 loess tablelands as samples to calculate average slope, axial ratio of top surface, gully density, top and bottom area ratio, percentage of negative terrain. The geometric mean of these five parameters was used as an index to estimate the relative age of the loess tableland. The index (abbreviated to I) was categorized into three levels: early development (I<1.74), middle development (1.74≤I<2.12) and late development (I≥2.12). The results showed that: (1) the morphological parameters of loess tablelands are different from one another in different developmental stages; (2) developmental stages are also inconsistent for the subtypes; (3) transitional type exhibits the characteristics more similar to the type of the previous stage. After calculating I of each subtype, we found that from early to late stages of the loess tablelands, I value increases gradually, which is consistent with other researchers' conclusions on the developmental stages of loess landforms.
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    Effects of different topographic attributes on determining appropriate DEM resolution
    HU Xuemei, QIN Chengzhi
    2014, 33 (1):  50-56.  doi: 10.11820/dlkxjz.2014.01.006
    Abstract ( 647 )   PDF (6386KB) ( 1215 )   Save
    Due to the scale effect of changing resolution for grid-based digital terrain analysis, it is important to determine an appropriate resolution (or a range of appropriate resolutions) for gridded digital elevation model (DEM) in practice. The commonly-used approach to determining appropriate resolutions is based on a scale effect curve characterized by certain types of statistics (the mean of local variance is commonly used), which is calculated on the multi-resolution dataset of a specific topographic attribute derived from the gridded DEMs with a series of spatial resolutions. The resolution with the highest value of the mean of local variance is considered to be an appropriate DEM resolution. Although several topographic attributes (such as slope gradient and curvature) have been used in this approach, there are few researches on the effects of different topographic attributes on the results from this approach. In this paper, we used an experiment to compare the effects of three types of topographic attributes (i.e., slope gradient, profile curvature, and horizontal curvature) applied to determining appropriate DEM resolutions. The experiment was conducted in three study areas with different terrain conditions, i.e. Xuancheng area with low relief, Coweeta area with high relief, and Kaixian area with more complex terrain conditions. The tested topographic attributes were calculated from the DEMs with a series of spatial resolutions (i.e., 5, 10, 15, 20, 25, 30, 50, 100, 150, 200, 300 m). For each topographic attribute, two widely-used algorithms were tested. One is proposed by Wood (1996), and the other is the one implemented in Arc-GIS software. The appropriate DEM resolution for a study area had the highest value of the mean of local variance derived from each tested topographic attribute, respectively. Experimental results showed that the effects of slope gradient and curvature are different on the results of the appropriate DEM resolution, while there is little difference between the results from profile curvature and horizontal curvature. The appropriate resolutions based on slope gradient information (i.e., 15, 50, and 100 m for Xuancheng area, Kaixian area, and Coweeta area, respectively) are coarser than those based on curvature information (i.e., 5, 10~15, and 5 m for Xuancheng area, Kaixian area, and Coweeta area, respectively), while the difference between them is less for the study areas with low relief. When slope gradient information was used, the appropriate resolution results for the study area with high relief are coarser than those for the area with low relief. When curvature information was used, the appropriate resolution results for the study areas with simple terrain conditions (such as Xuancheng area with low relief, and Coweeta area with high relief) are finer than those for the study area with complex terrain conditions. The range of appropriate resolutions from each topographic attribute for the study areas with simple terrain conditions is much wider than that for the study areas with complex terrain conditions. For each specific topographic attribute there is no difference between the effects of the tested algorithms of topographic attribute on the results of appropriate resolutions.
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    Spatial patterns of scale effect of specific sediment yield in Haihe River Basin
    YAN Yunxia, WANG Suiji, YAN Ming, HE Li, CHENG Dongsheng
    2014, 33 (1):  57-64.  doi: 10.11820/dlkxjz.2014.01.007
    Abstract ( 913 )   PDF (4538KB) ( 1271 )   Save
    Building specific sediment yield map is important for planning of soil and water conservation. While the traditional method to build a specific sediment yield map usually ignored the scale effect on specific sediment yield, namely, the influence of drainage area on specific sediment yield, many researches have proved there is a functional relation between specific sediment yield and drainage area. Therefore, the scale effect should be considered when building specific sediment yield. In this paper, the scale effect of specific sediment yield is studied in the Haihe River Basin. Following the principles of integrity of river basin and the similarity of topography, the Haihe River Basin is divided into 9 sub-regions. The scale effects of all sub-regionson specific sediment yield could be classified into three regional trends: (1) a flat trend; (2) a decreasing trend; (3) an increasing trend. Scale effect for each sub-region is explained based on location, topology, geomorphology, and land use forms. Sub-regions with flat trends are mainly located in the areas of mountainous upper reaches and limited flood plains of lower reaches. Soil erosion is severe in mountainous area, and sediment has little chance to silt down on flood plains. Sub-regions with decreasing trends are mainly located in the areas of limited mountainous upper reaches and large flood plains of lower reaches, where sediment transported from mountains have more chance to silt down. There is only one sub-region with increasing trend, located in the upper reaches of the Baihe River Basin and extended from grassland with slightly soil erosion to the loess covered area with severe soil erosion. Equations are used to offset the influence of drainage area on specific sediment yield, and specific sediment yields of all hydro-stations are all calculated under a standard area. Kriging interpolation is used to create specific sediment yield maps on standard area of 1000 km2 using equation of each sub-region. The pattern of specific sediment yield map shows strong soil erosion in the west and low erosion in the east, consistent with topographic distributions of the Haihe River Basin, with mountains in the west dominated by erosion and plains in the east dominated by deposition. There are two high specific sediment yield areas. One is located in the upper reaches of the Yongdinghe River Basin, Daqinghe River Basin, and Fuyanghe River Basin, with underlying surfacecovered by loess. The other one is located in the middle reaches of the Luanhe River Basin, expanding from loess to earth-rocky mountainous area. Those high value areas are the key areas for planning soil and water conservation.
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    Quantification of impacts of precipitation and human activities on runoff changes in different sections of Songhua River during 1955-2010
    WANG Yanjun, WANG Suiji, Su Teng
    2014, 33 (1):  65-75.  doi: 10.11820/dlkxjz.2014.01.008
    Abstract ( 639 )   PDF (5388KB) ( 1056 )   Save
    The surface runoff of some rivers in the world has decreased significantly with global or regional climate changes and increasing human activities, which has caused severe eco-environmental problems. The Songhua River is a large river in Asia and its basin is an important bread basket in China. The runoff of the whole river basin and in different sections has experienced dramatic changes over the last few decades. It is necessary to study the trend of the runoff changes and quantify the influencing factors on the changes. Based on annual runoff data at 4 gauging stations in the mainstream of the river and annual precipitation data from 61 meteorological stations in and around the river basin during 1955-2010, a decreasing trend of annual runoff and precipitation for four sections (above Jiangqiao, Jiangqiao-Dalai, Dalai-Haerbin and Haerbin-Jiamusi) was revealed using the linear trend method. The cumulative anomaly was employed to detect the abrupt changes of each runoff series. Three inflexion years for the runoff incremental changes were detected and they divided the entire period into four parts: above Jiangqiao (1963, 1982 and 1998), Jiangqiao-Dalai (1962, 1985 and 1998), Haerbin-Jiamusi (1966, 1980 and 1998), and only one turning year (1988) was found in Dalai-Haerbin section. The first period (T1) is regarded as the baseline period; the others are measurement periods. Without considering the effect of evapotranspiration, the slope change ratio of cumulative quantity (SCRCQ) was adopted to estimate the impacts of precipitation and human activities on runoff changes for the sections. In above Jiangqiao (T2: 1964-1982, T3: 1983-1998), Jiangqiao-Dalai (T2: 1963-1985, T3: 1986-1998) and Haerbin-Jiamusi (T2: 1967-1980, T3: 1981-1998) sections, the impacts of human activities on runoff incremental decrease were 71%~88%, 94%~97% and 72%~85%, respectively, while those of precipitation were 12%~29%, 3%~6% and 15%~28%, respectively, for the measurement periods of T2, T3 and T4 (1999-2010) compared with T1. In the measurement period (1989-2010), the impact of human activities on runoff changes in Dalai-Haerbin section was 75%, while that of precipitation was 25%. Obviously, the human activities were the most important factor causing runoff yield reduction in the later three periods for different sections of this study area. In addition, the impacts of human activities on runoff yield changes reached the maximum in the 1980s and 1990s. Although the runoff yield for different sections showed different variation characteristics, the reduction is mainly due to population increase and construction of water conservation projects.
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    Progress and prospect of Karst rocky desertification research in Southwest China
    YAO Yonghui
    2014, 33 (1):  76-84.  doi: 10.11820/dlkxjz.2014.01.009
    Abstract ( 826 )   PDF (1008KB) ( 1246 )   Save
    Karst rocky desertification is the third severe land degradation in China, following desertification in the north and soil and water loss in the Loess Plateau. This paper reviewed the progress and problems in the studies of Karst rocky desertification, and proposed a new method, which is temporal trajectory analysis based on high-resolution remote sensing data. At present, we have achieved great progress in the fields such as karst geology and geomorphology, restoration and reconstruction of Karst ecosystem, spatial pattern and dynamic changes of rocky desertification, evolution mechanism of karst rocky desertification as well as monitoring methods based on remote sensing. However, there are still a number of problemsin the studies of evolutional process of karst rocky desertification: (1) Current studies are mainly focusing on the spatial pattern of the rocky desertification based on remote sensing data and have successfully described the degree of severity of land degradation, but few of them are concerning the evolutional process of karst rocky desertification; (2) Most of the studies on the evolutional mechanism of Karst rocky desertification are qualitative descriptions and few of them are quantitative analyses; (3) The remote sensing monitoring methods normally are the double temporal variation detection method based on the "two time cycle" scales; only the information of "change/no change" or "what changes from what" can be acquired. Therefore, a new method, temporal trajectory analysis based on middle/high resolution remote sensing data, is introduced in this paper. This methodfocuses on "continuous" variations in a long time scale, and it is concerning not only what has changed between two time points, but also "where" and "how" the changes happened. By the temporal trajectory analysis method, the rocky desertification process in a long time series can be investigated, and the development of rocky desertification can be quantitatively and spatiallytracked, so that we can know where, how and why the rocky desertification has happened. Temporal trajectory analysis method has advantages in discovering the evolutional process of rocky desertification. Moreover, quantitative analysis ofthe pattern, process and evolutional mechanism of Karst rocky desertification will be the trend in the future.
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    Research progress in WaTEM/SEDEM model and its application prospect
    SHENG Meiling, FANG Haiyan
    2014, 33 (1):  85-91.  doi: 10.11820/dlkxjz.2014.01.010
    Abstract ( 1348 )   PDF (2424KB) ( 1372 )   Save
    Currently, many different erosion and sediment transport models are available. They are important tools to predict soil erosion and sediment yield under different conditions. The most commonly used models include Universal Soil Loss Equation (USLE), Revised Universal Soil Loss Equation (RUSLE), Water Erosion Predict Project (WEPP), Soil and Water Assessment Tool (SWAT), and the Limburg Soil Erosion Model (LISEM), et al. The physical distributed soil models can be well used in other regions once they were built in a given region. Therefore, physical soil erosion model hasreceived more attentionover the decades. However, the structures of the physical erosion models are usually complex and a lot of parameters are required to run them, which to some extent limits their applications. The Water and Tillage Erosion Model and Sediment Delivery Model (WaTEM/SEDEM) developed at the Physical and Regional Geography Research Group, KU Leuven University, Belgium, is a spatially distributed soil erosion and sediment delivery model. Unlike other more sophisticated dynamic models, this model requires minimal basis data input and the model structure is simple, similar to RUSLE model. Although WaTEM/SEDEM has data requirement almost similar to RUSLE model, it can assess both water and tillage erosion simultaneously. Mostly importantly,WaTEM/SEDEM can spatially model soil erosion and sediment deposition rates as well as the soil redistribution patterns. This model also allows incorporation of landscape structure or the spatial organization of different land units and the connectivity, and can then be used to delineate sediment source areas in an agricultural landscape, and to simulate the impact of various scenarios of an integrated catchment management on the rates and patterns of soil loss and sediment delivery. Therefore, WaTEM/SEDEM can provide useful information for land managers to implement rational management to control soil loss. Up to date, the model has been successfully used in Europe and other regions around the world. However, few studieshave been conducted in China using this model. In this paper, the model structure, the algorithms used to calculate soil erosion and sediment transport, the model input and output, and its applications were systematically introduced. A case study in Shuangfengtan catchment, Hunan Province was also reported in this paper to verify its usefulness. Besides the advantages mentioned above, the disadvantages of this model were also pointed out. For example, WaTEM/SEDEM does not predict sediment transport within a river, bank erosion or floodplain sediment deposition. At the end of this paper, the prospect of the application of WaTEM/ SEDEM in the data-limited regions was discussed.
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    Industry and Regional Development
    Spatial pattern of economic linkage network in Central Plains Economic Zone
    PAN Shaoqi, LI Yating, GAO Jianhua
    2014, 33 (1):  92-101.  doi: 10.11820/dlkxjz.2014.01.011
    Abstract ( 713 )   PDF (12046KB) ( 940 )   Save
    The Central Plains Economic Zone is an important engine of the central plains rising strategy, and it is also the strategy fulcrum of the regional coordinated development. Building a scientific and reasonable regional economic relation network is an important part of the construction of the Central Plains Economic Zone. This paper takes the CentralPlainseconomiczone as astudy area and its counties as the network nodes. The economic relation intensity among 231 nodes in 1996 and 2010 are calculated based on the gravity model. The regional quantity in the model is represented by the geometrical mean of GDP and population of the nodes. The GDP of 2010 have been deflated to the price level of 1996. The distance coefficient is represented by the shortest journey time by highway between the cities. Economic linkage network has been built in terms of the first, top5 and top10 in connecting intensity of each nodes, using the tools of GIS and method of Social Network Analysis to analyze the spatial pattern and evolutional characteristics of the network, and the analysis is mainly based on the concept of degree, degree distribution, clustering coefficient and betweenness centrality, etc. The results show that: (1) The CentralPlainseconomiczone has an unbalanced economic linkage network, and the distribution of the node degree exhibit an obvious rightward "inclined long-tailed distributions". The number of nodes with degree less than or equal to the median accounts for more than 85% of the total number of nodes, and a small number of nodes hold the absolute network power. Zhengzhou is the center of the network, while Luoyang and Handan are the sub-centers. The connectivity of the central and northern nodes is relatively strong, while measures should be taken to increase the connectivity of the eastern and southern nodes. (2) The network power gap between the central and marginal nodes is further widening, and the Gini coefficient and concentration ratios (CR1,CR5,CR10) of the node degree have increased significantly from 1996 to 2010.Thenetworkpowerofthecorenodesfurther increases, whilethe connectingabilityofthemarginalnodesdeclinesgradually. Theunbalancednetworkdevelopment is more pronounced,and this will restrain the interactional development between the CentralPlainsEconomicZone and its adjacent regions.(3) The network has a multiple hub-and-spoke structure. The correlation between the node degree and clustering coefficient is significantly negative. This proves that the nodes with high degree are the main connection objects of the adjacent nodes, while there are fewer mutual connections between the peripheral nodes. With the high degree nodes as the core, the network formed several sub-networks with hub-and-spoke structure of different levels. Zhengzhou is the primary hub, and plays as the core leading role for the entire economic zone, while Luoyang, Handan and Luohe are the secondary hubs, mainly playing the roles of leading and radiating for the surrounding cities and counties. The construction of the cross-shape development axis and "米" glyph development zone will strengthen the economic linkage between the primary hub and the secondary hub, it will also help the entire region to realize the advantageous complementarities and linkage development. (4) The broker nodes play an important intermediary role in the network connectivity, and the betweenness centrality is not only closely related to the node degree, but also influenced by its location in the network. The broker nodes in the economic linkage network of the Central Plains Economic Zone are mainly located in the Central Plains City Group, so the development of the Central Plains City Group will have significant impact on improving the whole connectivity of the network.
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    Evolution of spatial-temporal pattern of county economic development in China during 1982-2010
    ZHOU Yang, LI Ning, WU Wenxiang, WU Jidong
    2014, 33 (1):  102-113.  doi: 10.11820/dlkxjz.2014.01.012
    Abstract ( 696 )   PDF (16594KB) ( 848 )   Save
    Studying the spatio-temporal pattern of county economic development is extremely important for revealing the evolutionary mechanism of regional economy and achieves the sustainable development of China's county economy. Although considerable research attention has examined the regional economic pattern of China at the provincial and national levels in a certain time, we currently know the least about the profiles of county economic development across different periods. There is general agreement in the regional geography community that understanding the dynamic pattern of county economic development can provide a scientific base for the policy making and the implementation of regional development planning. Thus, the spatio-temporal pattern of county economic development in China merit further investigation. Based on the 2352 counties' per capita GDP in 1982, 1990, 2000 and 2010, the spatial autocorrelation analysis and variogram were used to investigate the evolutionary characteristics of spatiotemporal patterns of county economic development and to explore the possible mechanism behind the changes in the spatial pattern. Results showed that the county economic development and growth exhibit a positive spatial autocorrelation, which indicates that some counties with similar economic development levels clustered. But the spatial autocorrelation of the economic growth over the past three decades was not obvious. Since 1982, the spatial concentration of the county economy increased gradually and the spatial dependence enhanced over time. The difference of county economic development in eastern area of China is greater than that in the middle and western regions. In all four studied years, there are nine county units with a "high-high" pattern of economic development, i.e., Wujin, Kunshan, Dantu, Taicang, Changshu and Wuxi. Meanwhile, there are about forty-three county units maintaining their locations of "low-low" pattern of economic development for all studied years. Furthermore investigations revealed that the proportion of the county unites with homogeneity economic level increased from 19.56% in 1982 to 27.26% in 2010, whereas unites with heterogeneity level decreased from 3.06% in 1982 to 2.55% in 2010. This result demonstrated that there was an obvious heterogeneity for China's county economic development and the polarization effect in county economic development was enhancing over time. Overall, the hotspot areas of China's economic development mainly clustered in the eastern and northern regions of China, while the hotspot ones were concentrated in its central, southern and southwestern areas. Furthermore, the continuity and self-organization of Chinese county patterns was enhancing, whereas the random components of spatial disparity patterns was decreasing over time, which means that the structural differentiation caused by spatial autocorrelation was becoming more apparent. There was a relatively good homogeneousness in the economic development in the direction of northeast-northwest. The possible drivers behind the county economic development patterns could be partly attributed to its economic location, regional development policy, special resources and background of historical development. Among these possible causes, the regional development strategies may be the external contributors to the evolution in regional economic patterns. These findings have important theoretical and practical significance on narrowing the gap between urban and rural development.
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    Location choice and its special shift for foreign real estate investment in China
    LAN Xiaohong, MA Yan
    2014, 33 (1):  114-123.  doi: 10.11820/dlkxjz.2014.01.013
    Abstract ( 601 )   PDF (2754KB) ( 980 )   Save
    Since the late 20th Century, the hotspots of international direct investment have transferred from manufacturing industries to service industries. The development of service international direct investment became the motor of global direct investment. As a result, the locational choice of service international direct investment has acted as a popular topic of economical geography. After thirty years' reforming and opening up, Chinese is now a major destination of international direct investment. The structure of international direct investment in China has also changed because of more critical policies and variable environments. Recently, the tertiary industries are attracting more and more foreign direct investment. However, there are little literatures about the location choice theories of foreign direct investment in the tertiary industries. The empirical literatures are even less. Real estate is one of the major industries that foreign direct investment focuses on. We hold the real estate industry as an example to study the location choice of foreign direct investment in Chinese tertiary industries. Special intention is paid to the interaction of foreign direct investment and domestic investment, especially the exclusion impact of domestic investment. Empirical study of the location choices of real estate foreign direct investment during 2006-2011 shows that although foreign real estate investment concentrates in the metropolises along the eastern seashore, it shows a trend to shift to the big cities in the inner land, especially to those cities locates along the Yangtze River. Compared to foreign direct investment from other regions and countries, foreign direct investment from Hong Kong, Macao and Taiwan spreads more widely in the inner land. The study uses a panel Tobit model to declare that intensive competitions from domestic real estate firms and disadvantages of outsiders make foreign firms to give up the optimized locations, where the profit rate is highest. Compared to foreign real estate forms, domestic real estate firms are much more familiar with the real estate market so that they deal with little uncertainty and risk. What's more, the regulations of domestic real estate firms are looser, and they may enjoy more flexible company frameworks and investment destinations. As a consequence, the domestic real estate firms have more market power than foreign real estate firms. The domestic real estate firms could occupy the optimal locations, known as "the first line cities" including Bejing, Shanghai and Guangzhou. Foreign firms move to suboptimal locations, where the market scale is large and the profit rate isn't highest, ensuring that they can increase the total sum of profit. Such cities are called "the secondary line cities", including cities located along the Yangtze River and capitals of eastern and central provinces. Because the levels of marketization of land in different cities increased rapidly in the past six years, foreign firms can chose locations without the restriction of land institutions. Additional analyses about the newly built-up foreign and domestic real estate firms indicate that the trend to transfer from "the first line cities" to "the secondary line cities" exists in both foreign and domestic firms.
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    Multidimensional evaluation of county poverty degree in Hebei Province
    YUAN Yuan, WANG Yanglin, MA Jing, WEI Hai, PENG Jian
    2014, 33 (1):  124-133.  doi: 10.11820/dlkxjz.2014.01.014
    Abstract ( 761 )   PDF (7798KB) ( 1171 )   Save
    With the economic integration of the Beijing-Tianjin-Hebei Region, there exists a poverty belt around Beijing and Tianjin within Hebei Province, which has received attention from academia and the public, so as to put the setting standards of poor counties into the spotlight. Despite some applications of not merely economic indicators but also social and natural indexes to identify poverty in academic researches, the setting of poor counties is only based on economic indicators in China. This paper adds indicators in social dimension representing human poverty and in natural dimension representing natural poverty to build a multidimensional poverty index system, and utilizes SOFM (self-organizing feature mapping) nonlinear clustering tool to classify all of the 136 counties in Hebei Province into 5 categories in view of the county poverty degree by the economic dimension & economic-social-natural dimensions separately. Clustering maps are compared with the map of currently poor counties in Hebei Province afterwards. The results show that the counties with low grades are the ones with high poverty degree. Meanwhile, counties with low grades are the majority, suggesting a high poverty degree all over Hebei Province. About the clustering results, whether in the single economic dimension or economic-social-natural dimensions, they are both consistent with the current distribution pattern of poor counties in Hebei Province which helps the transformation of "relative poverty" to "absolute poverty". Besides, in comparison to the results based on the single (economic) dimension, multidimensional (economic-social-natural) evaluation is more comprehensive because it takes current situation and potential of poverty into overall consideration. Furthermore, potential poverty degree in the natural dimension influences the comprehensive poor degree, indicating that both the current and potential poverty degree of poverty areas around Beijing and Tianjin are high and the region should cooperate with Beijing and Tianjin actively. In contrast, the potential poverty degree of poor counties in the south and middle Hebei Province is relatively low and the region is more easily to be lifted out of poverty. Moreover, these regions covers many counties that are not considered to be poor ones but very likely to become poor ones. Therefore, these regions deserve more attention and being treated differently. To make advances in the poverty relief and development work, the government should not only deal with things distinctively but also combine prevention with treatment and link the areas together. In this way we can expect the achievement of Beijing-Tianjin-Hebei coordinated development and the harmoniously simultaneous growth of wealth of society.
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    Spatial pattern and its mechanism of modern logistics companies in China
    WANG Chengjin, ZHANG Mengtian
    2014, 33 (1):  134-144.  doi: 10.11820/dlkxjz.2014.01.015
    Abstract ( 670 )   PDF (3096KB) ( 1299 )   Save
    Logistics company is an economic entity to specialize in organization and operation of logistics activities and has a strategic significance in supporting various economic activities of circulation field and effective operation of the whole social-economic system, even impacting the reorganization of regional spatial structures. However, review articles in the literature show that for a long time most scholars only pay attention to the distribution features or spatial modes of logistics companies at the city scale and organization mode of logistics operational network at the regional or national scale, due to the limit of data collection and methodology, but the distribution patterns of logistics companies and the dynamic mechanisms at the national scale are seldom investigated. Particularly, the number of logistics companies has been increasing explosively since the end of 1990s in Mainland China. For this purpose, in this paper, we choose 1855 A-level logistics companies, rated by the government authority by various criterions over the past seven years, as the study samples, from the spatial scales of region, province and city, to describe and analyze the spatial features of the logistics companies in China, including the overall pattern, spatial centralization, coverage and spatial differentiation. And we explore the dynamic mechanisms of spatial disparities of logistics companies' distribution from the multi aspects. The results show that there are obvious spatial distribution disparities among the logistics companies in China. The coastal region has more logistics companies than inland region and their numbers show a "2:1" ratio. Interestingly, the eastern region also has obvious larger number than central and western regions, with "4:2:1" ratios. Generally, the southern provinces have more logistics companies, and the northern, northeastern, northwestern and southwestern provinces have fewer. Furthermore, the southeast coastal provinces especially Jiangsu and Zhejiang have the most companies. The spatial disparity of logistics companies' distribution among the cities seems to be more significant, showing clear separation of aggregation regions and sparse regions. The logistics companies not only are concentrated in the provincial capitals and economic centers, but also cover a large number of prefectural-level cities, even extending into many counties. More interestingly, South Jiangsu, Shanghai, South Anhui and Zhejiang have a large number of logistics companies and large coverage of various cities. But in each province, logistics companies are mainly located at the capital city and important economic centers and port cities. Logically, this spatial pattern is determined by the various factors combined. The results also show that the economic scale and industrial structure (among eastern, central and western regions, or between northern and southern regions), opening up and international trade, location and transport condition become the important factors to influence the spatial differentiation of logistics companies' distribution. It`s noteworthy that the development of a large number of local and specialized industrial clusters and private economies promotes the emergence and centralized distribution of logistics companies in Zhejiang and Jiangsu. More strikingly, the logistics planning and support policies made and provided by local governments also profoundly influence the development and flourish of logistics market and companies, especially in the coastal region and large cities of central and western regions. Theoretically, this distribution disparity among logistics companies generates different supporting capabilities for each region to operate the socio-economic system effectively. This research can provide a guidance to optimize the distribution of logistics companies and organize the logistics activities.
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