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Table of Content

    28 September 2016, Volume 71 Issue 9 Previous Issue    Next Issue
    Orginal Article
    Frontiers in terrestrial system research in Chinaunder global change
    Du ZHENG, Shaohong WU, Yunhe YIN, Qinye YANG, Dongsheng ZHAO, Xueqin ZHANG
    2016, 71 (9):  1475-1483.  doi: 10.11821/dlxb201609001
    Abstract ( 1142 )   HTML ( 6 )   PDF (2556KB) ( 1823 )   Save

    In view of the regional differentiation rules of land surface, research on terrestrial system (TS) has provided significant basis for the rational development of natural resources and layout of industries, and supported regional sustainable development as well. In this paper, the progress of TS research in China is overviewed and research frontiers in TS research in the near future under global change are explored. Since the 1950s, China has paid great attention to the TS study as its socio-economic development, and conducted research on physical geographical regionalization, eco-geographical regionalization and comprehensive regionalization. Along with the deepening of global change research, dynamics of TS have been highly concerned. During the studies, methodology has been developed from qualitative research of integration of experts' brainpower gradually to quantitative research based on field observation and experiments of the natural processes, including physical, chemical and biological processes, as well as application of information technology and mathematical simulation. Along with the emphasis on global change, TS would be combined with the ideology, objectives and key researches of Future Earth program, to focus on the mechanism and regional effects of interaction among land surface elements, the response of TS to global change, the quantitative recognition on regional unit boundary, and the combination of physical and human elements.

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    Continuation and innovation of integrated studies in physical geography
    Shaohong WU, Dongsheng ZHAO, Yunhe YIN, Qinye YANG, Xueqin ZHANG
    2016, 71 (9):  1484-1493.  doi: 10.11821/dlxb201609002
    Abstract ( 971 )   HTML ( 5 )   PDF (543KB) ( 1332 )   Save

    A key characteristic of physical geography is the integrated study, which regards key physical factors of land surface, such as geomorphology, climate, hydrology, vegetation and soil, as a whole to examine interaction mechanism of the factors and land surface pattern caused by the interaction. As an outstanding geographer and Academician of the Chinese Academy of Sciences, Professor Zheng Du has long been endeavoring to promote the studies of theory and practice on integrated physical geography and obtained initiative achievement. In the research on spatial pattern and differentiation of physio-geographical regions of the Qinghai-Tibet Plateau, he established a vertical zonality system on plateau's montane area, announced the law of three-dimensional zonality on the plateau, clarified the developing mechanism of unique geo-ecological landscapes of the plateau and their spatial pattern, identified altitudinal cold and dry core region on the earth and developed regionlizational scheme of physio-geographical of the Qinghai-Tibet Plateau. In the research on physical geographical regionalization, he constructed principle and methodology of physio-geographical regionalization on plateau and mountain, and proposed a novel scheme of China's eco-geographical regionalization. His theory and methods was widely applied to guide ecological construction. He placed emphasis on observing differential regulation of physio-geographical regions and respecting natural law in ecological construction, and further pointed out that harmonious relationship between economic development and environmental protection should be paid more attention in use of water and land resources in developing arid regions of northwest China. Based on ideal of harmony between man and nature, he strived to promote research and practice of environmental ethics in regional sustainable development. In this paper, the authors review Professor Zheng Du's studies and practices in integrated physical geography over the last 50 years or more in order to understand his systematic theories and innovative research methodology in this field.

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    Spatial-temporal characteristics of soil moisture in China
    Lei ZHANG, Houquan LU, Liangyu WANG, Bingyun YANG
    2016, 71 (9):  1494-1508.  doi: 10.11821/dlxb201609003
    Abstract ( 2090 )   HTML ( 8 )   PDF (3247KB) ( 2015 )   Save

    Using actual observed soil moisture data of 155 agro-meteorological stations across China, at dekadal scale from 1981 to 2010, this paper examined the spatial and temporal characteristics of soil moisture at each 10 cm depth from 0 to 50 cm, at regional and national scales. Annual trend and significant change point were detected through tendency analysis and Cramér-von Mises test methods. Since soil texture and crop types were approximately homogeneous in each climatic region, regional average variation of soil moisture could be observed in the analysis. Mean soil moisture was between 15% and 25% in most regions while it was above 25% in the northern part of Northeast China and southern part of Southwest China. At each depth, larger soil moisture was detected in Southwest China, Jianghuai, Northeast China, Jiangnan, Jianghan, Huanghuai and South China, while the smallest value was observed in Inner Mongolia. As soil deepening, except in Tibetan Plateau, increases in soil moisture were apparent, being a maximal magnitude in Southwest China. Obviously, as well as periodical characteristics, annual and seasonal difference of soil moisture emerged at each depth, corresponding well to regional precipitation, temperature, and water demand for planting crops. An obvious freezing-increasing-deceasing-increasing trend existed in Northeast China, Inner Mongolia and Xinjiang, a variation of deceasing-increasing-fluctuating in North China, Huanghuai, and eastern Northwest China, a multiple fluctuation in Jianghuai, Jianghan and Jiangnan, and a deceasing-increasing-deceasing trend in South China and Southwest China, while an increasing-deceasing trend was found in the Tibetan Plateau. Soil moisture at a greater depth was higher than that at superficial layers. Annual soil moisture varied at each depth, but the mean value decreased from 1981 to 2010. Such annual variation could be well explained by corresponding temperature and precipitation. Consequently, soil moisture tended to decrease in response to temperature increase, following climate change. Apart from climatic factors, soil texture and crop type, as well as human activity, can have influence on soil moisture, which is needed to be studied further. Soil moisture decreased in Xinjiang, South China, North China, Tibetan Plateau, Northeast China and Huanghuai among which Xinjiang was most remarkable with a velocity above -2.3%?(10a)-1. Except in Jianghuai, a significant change of soil moisture was detected, mainly during two periods, i.e. from the late 1980s to early 1990s, and late 1990s.

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    Variation of channel lateral erosion/accretion and channel shrinkage rate in the Linhe Reach of the Yellow River since 1977
    Yanguo MEI, Suiji WANG
    2016, 71 (9):  1509-1519.  doi: 10.11821/dlxb201609004
    Abstract ( 1291 )   HTML ( 13 )   PDF (1857KB) ( 1460 )   Save

    Taking the Linhe reach of the Yellow River with a channel length of 213 km as an example, this paper evaluated the area changes of channel bank erosion/accretion in four sub-reaches (S1, S2, S3 and S4) during 19 different periods on the basis of remote sensing images since 1977. Furthermore, the mean channel shrinkage rate for the whole river reach was obtained. The results show that the left and right banks of the Linhe reach were dominant in lateral net accretion during the period 1977-2014. For the left bank of the four sub-reaches, the accumulative lateral accretion areas during 1977-2014 were 33.16 km2, 49.59 km2, 29.52 km2 and 30.85 km2, respectively, while the lateral accretion areas during 1995-2000 accounted for 85.5%, 51.2%, 47.2% and 104.6% of the accumulative values, respectively. For the right bank of the four sub-reaches, the accumulative lateral accretion areas in 1977-2014 were 30.83 km2, 8.74 km2, 26.44 km2 and 18.76 km2, respectively, while the lateral accretion areas during the period 1995-2000 accounted for 57.2%, 111.9%, 65.7% and 61.6% of the accumulative values, respectively. The channel area of the Linhe reach was characterized by a reduction tendency from 1977 to 2001, and alternate erosion and accretion after 2001. The channel mean shrinkage rate of the Linhe reach was 6.16 km2/yr during the period 1977-2014. The most remarkable change of channel planform of the Linhe reach also occurred in the 1990s. Compared with 1995, the channel length and sinuosity increased by 5.8% and 6.6% and the channel area and mean width decreased by 39.4% and 42.8% in 2000, respectively. Significant channel planform changes and channel shrinkage for the Linhe reach occurred in the 1990s, which was mainly influenced by the joint-operation of the Longyangxia and Liujiaxia reservoirs since 1986, which resulted in substantial reductions of runoff and sediment fluxes in flooding season in a year. In addition, the bankerosion-accretion for the the four sub-reaches was also affected by the physical properties of local bank, protection engineering of channel bank and hydrodynamic differences. With the implementation of integrated river management measures since 2000, these changes have been significantly weakened and the river's health has been restored.

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    Overflow probability of the Salt Lake in Hoh Xil Region
    Xiaojun YAO, Meiping SUN, Peng GONG, Baokang LIU, Xiaofeng LI, Lina AN, Chao MA
    2016, 71 (9):  1520-1527.  doi: 10.11821/dlxb201609005
    Abstract ( 926 )   HTML ( 10 )   PDF (3370KB) ( 1578 )   Save

    After the bursting of Huiten Nor in Hoh Xil region in September, 2011, the topic on whether the water overflow from the Salt Lake would enter the Chumaer River and become the northernmost source of the Yangtze River has aroused wide concern from public and academic field. Based on Landsat TM/ETM+/OLI remote sensing images during 2010-2015, SRTM 1 arc-second data, Google Earth DEM data and the observation data from the Wudaoliang meteorological station, the study analyzed the variation of the Salt Lake and its overflowing condition and probability. The results showed that the area of the Salt Lake expanded sharply from October 2011 to April 2013, and then it stepped into a stable expansion period. On October 27, 2015, the area of the Salt Lake reached an area of 151.38 km2, or about 3.35 times that of the lake on March 3, 2010. The Salt Lake will overflow when its area reaches the range from 218.90 km2 to 220.63 km2. Due to the differences of the data between SRTM and Google Earth DEM, the water level of the Salt Lake modeled would be 12 m or 9.6 m higher than the current level when the lake overflowed, and its capacity would increase by 23.71 km3 or 17.27 km3, respectively. Meanwhile, the overflowed water of the Salt Lake would run into the Qingshui River basin from its eastern part. Although the Salt Lake does not overflow in the coming ten years, with watershed expansion of the Salt Lake and the projected precipitation increase in Hoh Xil region, that fact that the probability of water overflow from the Salt Lake and the lake is becoming a tributary of the Yangtze River will exist in the long term.

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    Coupling relationship among speleothems, geological background and cave environment
    Yuelong WEI, Weihai CHEN, Qukan LUO
    2016, 71 (9):  1528-1543.  doi: 10.11821/dlxb201609006
    Abstract ( 726 )   HTML ( 5 )   PDF (8640KB) ( 1298 )   Save

    Based on landscape formation mechanism and its principles for karst landform and speleothems, "cave"--the jointly processing object -- has been studied through dynamical coupling methods and system. A cave has been studied by correlating its regional geological background, internal and external environment with speleothems formation organically. A coupling system for speleothems formation has been thus created, which has generalized the content, characteristics and significance. At the same time, it has examined the regional geological background of Shuijing Cave in Bama of Guangxi, the external environment (climatic features and evolution, CO2 source and conversion of karst water, evolution of recharge and development of karst water, vegetation, soil types and soil covering features, etc.) and internal environment (infiltration patterns and amount of karst water from cave wall, cave atmosphere, CO2 content, temperature and humidity, etc.) systematically. Besides, it has also analyzed the coupling process of speleothems formation in Shuijing Cave comprehensively. According to different regional tectonic movement extents and speleothems’ features in different geological periods, the coupling process of the speleothems formation could be identified into 4 recyclable periods: (1) early stable period of regional tectonic movement -- the speleothems were formed and developed; (2) middle stable period of regional tectonic movement -- the speleothems were developed in large scale; (3) late stable period of regional tectonic movement -- the speleothems were developed slowly or even ceased growing; (4) intermittent regional tectonic movement -- the speleothems began to collapse.

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    Ecological risk assessment of landslide disasters in mountainous areas of Southwest China: A case study in Dali Bai Autonomous Prefecture
    Yueyue DU, Jian PENG, Shiquan ZHAO, Zhichao HU, Yanglin WANG
    2016, 71 (9):  1544-1561.  doi: 10.11821/dlxb201609007
    Abstract ( 976 )   HTML ( 6 )   PDF (8119KB) ( 1807 )   Save

    Taking Dali Bai Autonomous Prefecture as an example, the study assesses ecological risk of landslide geological disasters in terms of risk stressors, risk receptors, exposure and response process, and ecological end points. To be specific, firstly, the information method is used to evaluate the hazard of landslide disasters. Secondly, ecological vulnerability is evaluated based on landscape pattern metrics. Thirdly, the potential ecological damage of the study area is identified according to the ecosystem service assessment. Finally, the ecological risk of landslide disasters is comprehensively evaluated, and the partitions of risk precaution and governance are distinguished. The results show that, (1) 10 aspects including geography, geology and human activity factors, such as elevation less than 1800 m, slope within 15°-25°, NDVI less than 0.31, are the best information combination for inducing landslide geographical disasters in Dali Prefecture. As to the hazard of landslide geological disasters, the whole Dali prefecture is generally at medium and high risk levels of landslide and debris flow disasters. And the risk of northwest is lower than that of southeast; (2) the areas with high ecological vulnerability are mainly concentrated in the south of the Red River watershed, southeast of the Jinsha River watershed and the central part of the Lancang River watershed. Watersheds with low ecological damage have relatively poor water conservation service and food supply service. Watersheds with medium ecological damage have obvious advantage in providing net primary production and soil conservation service. Watersheds with high ecological damage would have relatively strong food supply and water conservation service; (3) the ecological risk of landslide disasters in Dali Prefecture presented 3 levels and 8 types of risk structures. Then 367 small watersheds were divided into 4 partitions of risk prevention and governance strategies, i.e., risk avoidance and warning areas, ecological protection and restoration areas, risk avoidance as well as ecological protection areas, and natural adaption areas.

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    Aeolian dynamical process of blowout on the fixed dune
    Yu SUN, Huishi DU, Eerdun HASI, Meiping LIU
    2016, 71 (9):  1562-1570.  doi: 10.11821/dlxb201609008
    Abstract ( 942 )   HTML ( 2 )   PDF (3830KB) ( 1250 )   Save

    Blowouts are the precursors to dune reactivation, which is the primary manifestation of desertification. Masts of three-cup anemometers, wind vanes, and sand traps were used to measure wind flows and sediment transport rates through a blowout developed on the fixed dune, which is located on the southern fringe of the Otingdag Sandy Land. Results demonstrate that after entering the blowout, airflow expanded and decelerated, reattached and accelerated, separated and suddenly decelerated, and gradually accelerated. The angle of incidence between the approaching wind and the blowout long-axis, local topography and vegetation significantly affected the airflow patterns and sediment transport rates. When winds approached from directions within 10° of the blowout axis, the deceleration zone moved westwards, airflow accelerated from the bottom of the blowout to the erosional walls and the depositional lobe; when the approach angles became oblique and equal or greater than 10° of the axis, the deceleration zone expanded eastwards, airflow accelerated and transported sediments to the east. Airflow reattachment and highly dense vegetation on the top of the depositional lobe captured and deposited considerable sediments, contributing to the increment of the height of the depositional lobe. The flow-form interactions within the study site gave rise to the deepening, elongating and widening of the blowout.

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    Applicability evaluation of CFSR climate data for hydrologic simulation: A case study in the Bahe River Basin
    Sheng HU, Mingming CAO, Haijun QIU, Jinxi SONG, Jiang WU, Yu GAO, Jingzhong LI, Kehong SUN
    2016, 71 (9):  1571-1587.  doi: 10.11821/dlxb201609009
    Abstract ( 1156 )   HTML ( 13 )   PDF (5760KB) ( 1898 )   Save

    To discuss the applicability of CFSR reanalysis data in the hydrologic simulation of watersheds, taking the Bahe River Basin as a case, this paper uses two types of weather data to establish SWAT hydrologic model, and carries out the runoff simulation from 2001 to 2012 of the Bahe River Basin on yearly and monthly scales, and makes use of such evaluation methods as repression analysis, Nash-Sutcliffe Efficiency (NSE) and Percent Bias (PBIAS) to compare the simulation effect of both data. At last it puts forward CFSR weather data correction method. The research results show: (1) To some extent, CFSR climate data has applicability for hydrologic simulation in the Bahe River Basin, the R2 value of the simulated results is above 0.50, the Nash-Sutcliffe Efficiency is above 0.33, and |Percent Bias (PBIAS)| is below 14.8. Although the quality of the CFSR weather data has some problems, it basically achieves a satisfactory result in the hydrologic simulation of the Bahe River Basin after rainfall data correction. (2) The simulated flow of the CFSR weather data is higher than the observed flow, the reason may be that there are more rainy days and the rainfall intensity is much stronger according to the estimation of day-to-day rainfall data by CFSR, which usually leads to the fact that the data will simulate a higher base flow and flood peak discharge in terms of the Water Balance, except for individual years. (3) The relation between the CFSR rainfall data and the observed rainfall data of the Bahe River Basin can be displayed by a power exponent equation: y=1.4789x0. 8875 (R2 = 0.98, P <0.001); the fitted equation of each CFSR station varies slightly from others. The equation just lays a theoretical basis for correction of the CFSR rainfall data.

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    Temporal and spatial variability of air temperature lapse rates in Mt. Taibai, Central Qinling Mountains
    Danping ZHAI, Hongying BAI, Jin QIN, Chenhui DENG, Rongjuan LIU, Hong HE
    2016, 71 (9):  1587-1595.  doi: 10.11821/dlxb201609010
    Abstract ( 942 )   HTML ( 17 )   PDF (1677KB) ( 1673 )   Save

    Air temperature lapse rate (γ) is taken as one of key input parameters when we evaluate the response of the mountain ecosystem to climate change, and its accuracy is very useful to the related research in the future. In this paper, based on the datasets built based on data from standard meteorological stations in Mt. Taibai, the tempo-spatial distribution characteristics for the variations of γ were evaluated by using DEM images at a 25-m resolution as well as daily average temperature during the period of 2013-2015. The average value of annual γ on the northern slope (0.513℃/100 m) was larger than that on the southern slope (0.499℃/100 m) during the three years, and a greater variation in different altitude regions was found on the northern slope than on the southern slope. The variability of γ was significant at different time-scales. At the seasonal scale, the peak of γ (0.619℃/100 m) on the northern slope occurred in summer, while the peak of γ (0.546℃/100 m) on the southern slope appeared in spring. Meanwhile, the minimums of γ on both slopes (0.390℃/100 m on the northern slope and 0.449℃/100 m on the southern slope) were found in winter. Compared with the southern slope, the values of γ on the northern slope were higher in spring and summer, while they were lower in winter and almost the same in autumn. At the monthly scale, the larger values of γ appeared in the warmer months on both slopes, and the larger variation in γ was found on the northern slope. The values of γ were higher on the southern slope than those on the northern slope in January, February, November and December, while they were lower from May to September. The results clarified the rule of temperature-altitude variations in Mt. Taibai in recent 50 years, which could provide a theoretical basis for the quantitative researches on temperature distribution characteristics and the response of the ecosystem to climate change in the mountain areas.

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    Review on the estimation of net primary productivity of vegetation in the Three-River Headwater Region, China
    Qingling SUN, Baolin LI, Fei LI, Zhijun ZHANG, Lingling DING, Tao ZHANG, Lili XU
    2016, 71 (9):  1596-1612.  doi: 10.11821/dlxb201609011
    Abstract ( 832 )   HTML ( 6 )   PDF (1495KB) ( 1621 )   Save

    As the "Water Tower of China", the Three-River Headwater Region (TRHR) is an important ecological shelter for national security and regional sustainable development for many Southeast Asian countries and the middle or lower reaches of main rivers in China. The TRHR has typical high and cold environment and alpine vegetation system. Net primary productivity (NPP), as a key vegetation parameter and ecological indicator, can reflect the natural environment change and the carbon budget level intuitively. Given the particular geographic environment and strategic position of the TRHR, many scholars have estimated NPP of the TRHR using different methods. For various reasons, however, the estimated NPP varies greatly. At present, a great deal of research involving NPP estimation has been conducted on the TRHR, but no paper has been published to summarize and assess these studies. Therefore, this paper (1) summarized systematically the related methods and results of NPP estimation in the TRHR by review of previous researches; (2) discussed the suitability of existing methods to the TRHR and pointed out the main problems; and (3) assessed the estimated NPP results. Finally, the development directions of NPP estimation in the TRHR were prospected.

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    The coupling interaction mechanism of regional water-land-energy-carbon system
    Rongqin ZHAO, Zhiping LI, Yuping HAN, KANDLIKAR Milind, Zhanping ZHANG, Minglei DING
    2016, 71 (9):  1613-1628.  doi: 10.11821/dlxb201609012
    Abstract ( 381 )   HTML ( 12 )   PDF (1779KB) ( 212 )   Save

    Water, land, energy and carbon are key elements of earth's surface system. Researches on regional water-land-energy-carbon system (WLEC system) will not only help to reveal the impact mechanism of resource coupling exploitation on carbon emissions, but also has great significance to explore low-carbon development mode based on water, land and energy saving. Based on the literature review, this paper analyzed the element relationship of regional WLEC system, discussed the coupling interaction mechanism, research perspectives and impact factors of regional WLEC system, and put forward the future research points in this field. The main conclusions are as follows: (1) Regional WLEC system reflects the interactions among different spheres of earth's surface system. Through water cycle, land use, energy flow and carbon cycle, WLEC system becomes the core of regional natural-economic-social system. It not only reflects the matching relationship and exploitation efficiency of regional resources, but also embodies the impact extent of human activities on environment. (2) Regional WLEC system can be divided into three subsystems: water system, land system and energy system. They interacted with each other and together formed the resource base for the regional socio-economic development. Regional carbon emission intensity is mainly determined by the need relationship among three subsystems, industrial activities and energy structure. (3) Regional WLEC system can be studied from different perspectives such as microscopic view, industrial activities and land use. (4) Regional WLEC system is influenced by natural, economic, social and pressure factors, in which economic factor, especially economic development level, production efficiency and technology, is the determinant factor of the function and efficiency of regional WLEC system. (5) In the future, modeling of regional WLEC system, relationship between WLEC system and climate change and food security, carbon emission efficiency of resource coupling exploitation and the integrated evaluation and regulation of WLEC system should be strengthened.

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    Spatial and temporal modes of prehistoric settlement distribution around Songshan Mountain
    Peng LU, Yan TIAN, Panpan CHEN, Duowen MO
    2016, 71 (9):  1629-1639.  doi: 10.11821/dlxb201609013
    Abstract ( 249 )   HTML ( 6 )   PDF (2374KB) ( 149 )   Save

    Spatial and temporal distribution patterns are very important for recognizing the formation and development of ancient civilizations. Indeed, different prehistoric settlement distribution modes, including 'centralized', 'average', and 'stochastic', correspond with different social organizations, site-choices, and human choice of, and adaptation to, the environment. By implementing GIS spatial and model analyses, the aim of this research was to study the spatial distributional patterns, mechanisms of formation, and evolution of the prehistoric settlements (9000-3000 years before present, aBP), which are located around Songshan Mountain. These settlements are grouped into four periods, namely the Peiligang Culture (9000-7000 aBP), the Yangshao Culture (7000-5000 aBP), the Longshan Culture (5000-4000 aBP), and the Xia-Shang Culture (4000-3000 aBP). Indeed, on the basis of this research a new model for explaining prehistoric settlement distribution was developed and applied, leading to three main results. First, prehistoric settlement distribution patterns for all four periods are centralized around Songshan Mountain. The Peiligang and Xia-Shang settlements had two cluster centers, respectively, while the Yangshao and Longshan settlements had three cluster centers each. Second, the distributional center of gravity for prehistoric settlements in this region presents migration from south to north, while Peiligang period settlements were mainly distributed to the south of Songshan Mountain, by the Yangshao period, the main concentration of settlements had begun to move northwards. This trend continued into the Longshan period, before finally differentiating along an east-west transect to the north of Songshan Mountain in the Xia-Shang period. Third, results show that the pattern and evolution of prehistoric settlement distributions were closely related to prevailing environmental conditions and human cultural developments. Indeed, because the main economy of the Peiligang period was hunting, fishing and gathering, most settlements at this time were either distributed on hills, near the mountain, on the high platform, or close to water. In the mid-Holocene, warm and moist weather conditions exerted a significant impact on the southern plain, and high and flat geomorphologic units closer to the mountain became ideal locations for settlements in the Yangshao and Longshan periods. By the time of the Xia-Shang periods, social organization had become more complex, so settlements began to concentrate intensively around the capital region. As a result, the area north of Songshan Mountain became the core region of settlement distribution.

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    Spatial and temporal pattern of the 4.2-3.5 kaBP settlements and its succession models in the south of the Songshan Mountain
    Zhongxuan LI, Guoxi WU, Cheng ZHU, Jinggang ZHENG, Kaifeng LI, Shixing JIAO
    2016, 71 (9):  1640-1652.  doi: 10.11821/dlxb201609014
    Abstract ( 648 )   HTML ( 5 )   PDF (4462KB) ( 1648 )   Save

    Being the birthplace of the Longshan Culture in Henan Province, the south of the Songshan Mountain has been focused due to its continuity and changes in settlement pattern. Considering the regional differences, the study area was divided into two parts: 1) the upper reaches of the Yinghe River, which have small plains along the valley, and 2) the upper region of Shuangji River, where the loess highlands and narrow valleys are distributed. Influenced by the 4 ka BP cooling event, natural disasters occurred frequently and the settlements tended to move towards high elevation areas. Also, terrain properties of the settlements, slope directions and gradients for instance, varied significantly. Unlike the Xia-Shang Period, the Rank-Size curves of the settlements showed equilibrium characteristics in the late Longshan Period, suggesting a result from interaction of multiple factors. Using domain analysis of Thiessen polygon, we found that environmental changes had greater influence upon the upper reaches of the Yinghe River than upon the upper region of the Shuangji River. With both the nature and the culture considered, this article suggested that the succession of the settlements was driven by cultural factors in the late Longshan Period. And in the Xia-Shang Period, to a large extent, the succession of the settlements corresponded to the rule of natural selection.

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    Mixing spatial-temporal transmission patterns of metropolis dengue fever: A case study of Guangzhou, China
    Haiyan TAO, Zhongzhe PAN, Maolin PAN, Li ZHUO, Yong XU, Miao LU
    2016, 71 (9):  1653-1662.  doi: 10.11821/dlxb201609015
    Abstract ( 1013 )   HTML ( 10 )   PDF (2747KB) ( 1332 )   Save

    This paper proposes a new method to model the spatial and temporal transmission network for infectious disease. Specifically, 679 cases from the early 11 weeks of the dengue fever outbreak in Guangzhou in 2014 are used to analyze the disease transmission characteristics. Three methods are adopted for the analysis. (1) We use extended Knox test to derive the main time and space interaction sectors at a distance of 1 km in two weeks and that of 5-7 km in one week. (2) We pair the cases from different areas to construct the space-time affinity transmission (STAT) network and the human daily movement transmission (HDMT) network. (3) We compare the assortativity, spatial characteristics, and the central network location between STAT and HDMT network by using complex network theories. The result shows that the percentages of overall cases included in the STAT and HDMT networks are 92.93% and 97.05%, respectively. This means that both STAT and HDMT network models imply the overall transmission of the dengue fever outbreak. STAT network is assortative, and presents the cross infection in neighboring areas. On the contrary, HDMT network is disassortative, and it displays the diffusion infection character of the dengue fever outbreak. We earmark the location of outbreak center as well as the diffusion center with the degree of closeness centrality in STAT network and the degree of betweenness centrality in HDMT network. This shows that the outbreak center approximately overlaps the spatial kernel density center of all cases, while the diffusion centers are located along the urban rapid transit routes.

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