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    20 May 2017, Volume 72 Issue 5 Previous Issue    Next Issue
    Research Progress
    Retrospect and perspective of geomorphology researches in China over the past 40 years
    Weiming CHENG, Chenghu ZHOU, Yuancun SHEN, Qiangyi LIU
    2017, 72 (5):  755-775.  doi: 10.11821/dlxb201705001
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    Geomorphology is one of main branchs of geography. The research achievements and prospects in geomorphology have received considerable attention for a long time. In this paper, we firstly gave a general retrospect of geomorphological research in China over the past 60 years, especially the research progresses in the last 40 years. Based on a summary of experience and a trendency of development, perspectives of geomorphological research direction in the future were provided. It is concluded that the discipline of geomorphology has made great progress in the aspects of geomorphological types, partitions, as well as their subdisciplines such as dynamic geomorphology, tectonic geomorphology, climatic geomorphology, lithological geomorphology, palaeogeomorphology. We believe that persisting in the unity principle between morphological and genetic types would be conductive for the development of traditional landforms and integrated landforms. In addition, five perspectives aim to enhance China's geomorphological research capacity. They are: (1) strengthening the research of basic geomorphology theory and the research of integrated geomorphology to expand the research space; (2) focusing more on the research of geomorphologic structure and geomorphologic function to improve the application ability of geomorphology; (3) constructing a comprehensive resource, environmental, and geomorphologic information system and building a sharing platform to upgrade the intelligent information industry of geomorphology; (4) putting more efforts on the research of coastal geomorphology and marine geomorphology to assist the transformation of China from a maritime country to an ocean power; and (5) cultivating talents and constructing research teams to maintain a sustainable development of China's geomorphological research.

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    Climate Change and Surface Processes
    The relationship between water level change and river channel geometry adjustment in the downstream of the Three Gorges Dam (TGD)
    Yunping YANG, Mingjin ZHANG, Zhaohua SUN, Jianqiao HAN, Huaguo LI, Xingying YOU
    2017, 72 (5):  776-789.  doi: 10.11821/dlxb201705002
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    In this study, data measured from 1955-2016 was analyzed to study the relationship between the water level and river channel geometry adjustment in the downstream of the Three Gorges Dam (TGD) after the impoundment of the dam. The results highlighted the following facts: (1) for the same flow, the drought water level decreased, however, flood water level changed little. The lowest water level increased, while the highest water level decreased at the hydrologic stations in the downstream of the dam; (2) the distribution of erosion and deposition along the river channel changed from "erosion at channels and deposition at bankfulls" to "erosion at both channels and bankfulls"; the ratio of low water channel erosion to bankfull channel erosion was 95.5% from October 2002 to October 2015, with variations in different impoundment stages; (3) the drought water level decrease slowed down during the channel erosion in the Upper Jingjiang River and the reaches ahead but sped up in the Lower Jingjiang River and the reaches behind; concrete measures should be taken to prevent the decrease in the channel water level; (4) erosion was the basis for channel dimension upscaling in the middle reaches of the Yangtze River; the drought water level decrease was smaller than the thalweg decline; both channel water depth and width increased under the combined effects of the channel and waterway regulations; and (5) the geometry of the channels above the bankfulls did not change much; however, the comprehensive channel resistance increased under the combined effects of the river bed coarsening, bench vegetation, and human activities; as a result, the flood water level increased markedly and moderate flood to high water level phenomena occurred, which should be considered. The Three Gorges Reservoir effectively enhances the flood defense capacity of the middle and lower reaches of the Yangtze River; however, the superposition effect of tributary floods cannot be ruled out.

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    Age and provenance of Younger Dryas paleo-aeolian sandlayers in the Jin-Shaan Gorges of the Yellow River
    Yuzhu ZHANG, Chunchang HUANG, Yinglu CHEN, Zhihai TAN, Lirong YANG, Yunxiang ZHANG, Haijun QIU, Bo LIU, Fazhu ZHAO
    2017, 72 (5):  790-803.  doi: 10.11821/dlxb201705003
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    Fieldwork investigations were carried out in the Hukou-Longmen reach in the Jin-Shaan (Shanxi-Shaanxi) Gorges of the Yellow River. Paleo-aeolian sand layers were found interbedded in the Late Pleistocene and Holocene loess-soil profile—Beisangyu profile (BSY). Analytical results, including field investigation, magnetic susceptibility, grain-size distribution, surface textures of quartz sand, and geochemical elements, indicate that the paleo-aeolian sands are medium-sized sandy fine sands, which were formed in a dry and windy climate. And the extreme drought events recorded by paleo-aeolian sand layers were dated to 12.5-11.6 ka, with optically stimulated luminescence (OSL) dating method. The extreme drought event coincided with the Younger Dryas that was recorded by the lacustrine sediment profiles and the aeolian loess-soil profiles in the desert/loess transitional zone in the adjacent region. The paleo-aeolian sands were sourced mainly from ancient riverbed sands in the Jin-Shaan Gorges of the Yellow River. The Jin-Shaan Gorges is situated in a semi-arid zone with a temperate continental monsoonal climate. The region responds sensitively to global change. During the Younger Dryas period, the region is in an extremely dry and cold environment, with strong winter monsoon and weak summer monsoon. The water level of the Yellow River will decline obviously. Consequently, floodplains and channel bars in the river are exposed in a broad area, and a large quantity of sand material drifts to the banks of the river under the force of the wind, which becomes the main source of the paleo-aeolian sand layer in the platforms on the gentle slopes on both sides of the river valley. These results would be of great significance in further understanding the temporal regularities of the extreme drought event and the relations between extreme drought event and monsoonal climate change.

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    Scenario deduction based emergency rescue plan assessment and decision optimization of urban rainstorm water-logging:A case study of Beijing
    Chao SUN, Shaobo ZHONG, Yu DENG
    2017, 72 (5):  804-816.  doi: 10.11821/dlxb201705004
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    The scenario deduction and dynamic pre-assessment of urban natural disasters emergency plan play vital roles in emergency decision optimization. However, traditional plan assessments usually consist of scenario deduction of time slices and post-disaster assessment based on limited information. Based on the full-chained multi-dimensional scenario deduction plan coupled with water-logging model and multi-agent urban road condition model, this article conducts pre-assessment of emergency plan with multi time scales and rescuing targets. By examining the scale of damaged cars and the number of people threatened by the disaster, the assessment is performed regarding the quantity of people, time, and spatial arrangement of the plan. Based on this, the article provides a new solution in conducting disaster scenario deduction plan and optimizing emergency decisions. The emergency plan based on the number of people indicates that the rescuing force is firstly arranged at areas with higher risk, including North Fengwo Road, South Fengwo Road, Guanglian Road and Lianhua Bridge. In reality, only limited force participates in rescuing in time, and the spatial direction based on the number of force plays a vital role in optimizing rescue decision. Meanwhile, we also prove that the amount of rescue force stands for the fundamental position in emergency dispose. From the emergency plan based on the initiating time of rescue, it can be seen that the best initiating time is between 45 and 75 minutes, and the appropriate time of initiating can efficiently avoid the improper configuration of rescue space due to the premature rescue and the loss of efficacy when it starts too late. Different spatial arrangements of rescue could lead to different rescue force arrangement features and optimized conditions.

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    Mechanism of barrier river reaches in the middle and lower reaches of the Yangtze River
    Xingying YOU, Jinwu TANG, Xiaofeng ZHANG, Yunping YANG, Zhaohui WENG, Zhaohua SUN
    2017, 72 (5):  817-829.  doi: 10.11821/dlxb201705005
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    The channel in the middle and lower reaches of the Yangtze River is characterized by staggered distribution of the bifurcated channel and the single-thread channel. The amplitude of change of river regime is stronger in a bifurcated channel than in a single-thread channel. The adjustment of the river regime in the upper reaches usually propagates to the lower reaches through the migration of the main stream line and causes the riverbed evolution of the lower reaches. Whether the adjustment of the river regime in the bifurcated channel can pass through a single-thread channel and propagate to the lower reaches will affect the stability of the overall river regime. Studies show that the barrier river reach can block the upstream channel adjustment from propagating to the lower reaches; therefore, it plays a key role in stabilizing the river regime. This study investigates 34 single-thread channel reaches in the middle and lower reaches of the Yangtze River. On the basis of the systematic summary of the regularities of riverbed evolution in the middle and lower Yangtze River, the control factors of barrier river reach are summarized and extracted: the planar morphology of single-thread and meandering; no flow deflecting node in the upper or middle part of the river reach; the hydraulic geometric coefficient is less than 4; the longitudinal gradient is greater than 1.2?; the clay content of the concave bank is greater than 9.5%; the median diameter of the bed sediment is greater than 0.158 mm. Derived from the Navier-Stokes equation, the calculation formula of the bending radius of flow dynamic axis is deduced, and then the roles of these control factors in restricting the migration of the flow dynamic axis and shaping the barrier river reach are analyzed. The barrier river reach is considered as such when the ratio of the migration force of the flow dynamic axis to the constraining force of the channel boundary is less than 1 at different flow levels. The mechanism of the barrier river reach is such that even when the upstream river regime is adjusted, the channel boundary of this reach can constrain the migratory amplitude of the main stream line and centralize the planar position of the main stream line under different upstream river regime conditions, providing relatively stable incoming flow conditions for the lower reaches, thereby blocking the adjustment of upstream river regime from propagating to the lower reaches.

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    Evaluation of urban high temperature vulnerability of coupling adaptability in Fuzhou, China
    Wei SHUI, Zhichun CHEN, Jieming DENG, Yajing LI, Qianfeng WANG, Wulin WANG, Yiping CHEN
    2017, 72 (5):  830-849.  doi: 10.11821/dlxb201705006
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    The extent of extremely high temperature is expanding under global climate change. The adverse effects of high urban temperatures are worsening, presenting great danger to the environment and human society, and are especially pernicious to urban human-environment compound systems. Adaptation is an important action to cope with the extremely high temperature, and the studies of high temperature vulnerability coupled with the adaptability factors have become the international hot spots and research frontiers. Fuzhou city, one of the high temperature cities in China, was evaluated as a case study in this research. Expert evaluation, analytic hierarchy process (AHP), geographical spatial analysis technologies, questionnaire survey and orderly multivariate logistic regression analysis were used to reconstruct the spatial evaluation index system of urban high temperature susceptibility of coupling adaptability. In this study, the high temperature vulnerability of Fuzhou, its spatial differentiation, scale dependence, hot spots and the influencing factors of adaptability were systematically evaluated. The results indicated that: (1) Six selected indices, namely age, housing area, out-of-home cooling frequency, health condition, degree of medical convenience and government efforts to alleviate the high temperature, had significant impact on city residents' adaptability. (2) The spatial distribution of urban high temperature vulnerability, exposure and adaptability in Fuzhou showed a spatial structure of "core-periphery" , and the high temperature vulnerability of Fuzhou showed the semi-enclosed spatial pattern with the characteristics of "high near the outer and low near the inner area". (3) Under the same background of regional high temperature exposure and susceptibility, the adaptability from individual to community and city government could significantly change the spatial distribution of urban high temperature vulnerability. The research results are expected to further the theoretical progress of urban high temperature vulnerability, and to provide the basis of decision-making for Fuzhou and other cities of the same category.

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    Land Use and Environmental Change
    Spatio-temporal effects of urban rail transit on complex land-use change
    Zhangzhi TAN, Shaoyin LI, Xia LI, Xiaoping LIU, Yimin CHEN, Weixian LI
    2017, 72 (5):  850-862.  doi: 10.11821/dlxb201705007
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    The study of the spatio-temporal effects of urban rail transit on land-use change is significant for the collaborative simulation of land use and urban rail transit. In this paper, high-resolution remote sensing images and POIs data were combined to acquire fine-scale land use information. A stepwise regression model and a land function classification method were used to investigate the spatial and temporal effects of urban rail transit on land-use change. The results indicated that low density residential land would be converted to high density residential land and commercial land under the influences of urban rail transit. The influences of rail transit on land use vary over its various stages, including planning, construction and operation. In the planning and operation stages, such influences are mostly found in suburban areas with better transport infrastructure, while in the construction stage, they are related to available areas for land development. The land function around the urban central stations has changed slightly due to the restriction of land, while the land function around the suburban stations has changed significantly. The transitions of land function will emerge when metro stations go into operation.

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    Evaluating the potential of vegetation restoration in the Loess Plateau
    Haidong GAO, Guowei PANG, Zhanbin LI, Shengdong CHENG
    2017, 72 (5):  863-874.  doi: 10.11821/dlxb201705008
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    The "Grain for Green" project has been initiated in the Loess Plateau since 1999, and would be continuously promoted in the future. Therefore, it is of important significance to assess the vegetation restoration and its potential in the Loess Plateau. In this paper, based on the SPOT VEG NDVI dataset, the trend analysis, Hurst exponent method, statistical methods and geographical spatial analysis technology were adopted. Results showed that NDVI from 1999 to 2013 had a significant upward trend and the vegetation of 2/3 of the area would continue to improve. In loessal areas, the analysis of vegetation response curve indicated that vegetation coverage had a significant exponential relationship with drought index. Such relationship of gentle slope was more obvious than that of steep slope. The best vegetation response function of soil and rock-mountainous areas was linear function. Its correlation coefficient was lower than that of loessal areas. In the future, the average vegetation restoration potential of the Loess Plateau could reach 69.75%, which was high in the southeast and low in the northwest of the plateau. The region with better vegetation restoration would have lower vegetation restoration potential index. The vegetation restoration potential was mainly concentrated in the northern sandy land as well as in the western hilly and gully area. Subsequently, the differences of vegetation restoration rate for this region under different precipitation thresholds were remarkable, among which the area with precipitation of 375-450 mm had fast vegetation restoration. The measures "adaptation to water conditions" should be taken so as to avoid soil drying for afforestation. The results provided scientific support for the construction of ecological civilization on the Loess Plateau.

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    Environmental changes and cultural exchange between East and West along the Silk Road in arid Central Asia
    Chengbang AN, Wei WANG, Futao DUAN, Wei HUANG, Fahu CHEN
    2017, 72 (5):  875-891.  doi: 10.11821/dlxb201705009
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    Based on environmental records, archaeological findings, and isotopic data, the environmental changes and cultural exchange between East and West along the Silk Road in arid Central Asia during the Holocene have been studied. The results show that the cultural exchange is definitely influenced by geographic setting and environmental changes. Hexi Corridor is located at the marginal area of monsoonal Asia, characterized by monsoon-westerly transitional model. From Xinjiang to Central Asia, the environmental change demonstrated uniform trends during the Holocene: the early Holocene witnessed dry environment conditions and desert vegetation, while during the mid and late Holocene, steppe vegetation expanded when moisture increased. The cultural exchange between East and West along the Silk Road took advantage of moisture conditions during the mid to late Holocene. Benefited from the improvement of environmental conditions, the cultural exchange between East and West accelerated after 2000 BC. During 2500-2000 BC, Eastern and Western agriculture met and integrated along the Silk Road, representing the beginning of prehistoric "Silk Road" along the Tianshan Mountains. Furthermore, during 2000-1000 BC, a mixed economy characterized by wheat/barley-millet-husbandry appeared in the oases along the Silk Road, and expanded to the Eurasia steppe after 1500BC, being a sharp contrast to the surrounding animal husbandry and continuing to the historic periods. Such spatial differentiation is the result of integrated geographic setting and cultural exchange between East and West. During the prehistoric period, Eastern and Western agriculture oppositely spread along the oases in a leapfrogging forward way. While during the historic periods, political factors were the primary controlling upon the Silk Road, but environmental change was still a factor that cannot be ignored.

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    Heavy metal enrichment and pollution of historical cultural layers in Kaifeng City, Henan Province
    Yanfang CHEN, Jianhua MA, Dexin LIU, Lei GU
    2017, 72 (5):  892-905.  doi: 10.11821/dlxb201705010
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    Several dynasty palaces in Kaifeng City were buried by flood sediments of the Yellow River, forming the unique spectacle of city overlapping city, which were taken as excellent and rare samples to assess heavy metal enrichment and pollution of historical cultural layers. Three sedimentary cores with a length of 25 m were drilled in April, 2012, of which two were located in the urban area of Kaifeng City (ZKsz and ZKyz), and the other one was located in the western suburbs of the city (ZKjm). Each core was split into 10 cm intervals mostly, for a total of 657 soil samples. Concentrations of Pb, Cd, Cu, Zn, Ni, Cr and Co in samples were measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), while Hg and As were analyzed with Atomic Fluorescence Spectrometer (AFS). The dating frameworks of all the cultural layers in different dynasties were established according to AMS14C dates, archaeological explorations and historical documents. The results showed that six cultural layers were found in all the three sedimentary cores, including the Warring States, Song-Jin Dynasty, early Ming Dynasty, mid-Ming Dynasty, late Ming Dynasty and Qing Dynasty. Enrichment factors (EF) were calculated to assess the enrichment of heavy metals in cultural layers. Enrichment of most heavy metals occurred in the cultural layers, and Hg contributed to the highest enrichment level. Enrichment levels of Hg in the cultural layers of the two urban cores (ZKsz and ZKyz) before the early Ming Dynasty were from significant to extremely high. Pollution load index (PLI) was used to identify pollution levels of heavy metals in cultural layers. Most cultural layers showed slight to moderate pollution, while Song-Jin cultural layers of the two urban cores were considered as moderate pollution. Mercury was the main pollutant of the two urban cores while Cu, Pb and Zn had minor effects on the pollution, due to the wide use of cinnabar with high Hg contents in the history. As for the cultural layers of ZKjm core, Cd, Cr, Hg and Pb made more contributions to the pollution. The results also showed the positive linear relationships between metal PLI of cultural layers and their corresponding population densities. The decreasing PLI values from the early Ming to late Ming Dynasty were influenced probably by the frequent floods of the Yellow River.

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    Spatial pattern and influencing factors of casualty events caused by landslides
    Ying WANG, Qigen LIN, Peijun SHI
    2017, 72 (5):  906-917.  doi: 10.11821/dlxb201705011
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    The economy of China has maintained rapid growth with an average annual GDP growth rate of 10.14% (in comparable price) from 2000 to 2012. During this period, China witnessed frequent landslide disasters, including 338,964 identifiable individual landslide disasters that resulted in 45,381 casualties, including 9,928 deaths. Analysis of the casualty events caused by landslides from 2000 to 2012 revealed that the spatial pattern of the casualty events was affected by terrain and other factors of the natural environment, which resulted in the distribution of casualty events being higher in the south region than in the north region. Hotspots of casualty events caused by landslides were in the western Sichuan mountain area and the Yunnan-Guizhou Plateau region, the southeast hilly area, the northern part of the loess hills, and the Qilian and Tianshan Mountains, among some others. However, their local distribution pattern indicated that they were also influenced by economic activity factors. To quantitatively analyze the influence of natural environment factors and human-economic activity factors, the binary logistic regression model was applied. The binary logistic regression model is a type of probabilistic nonlinear regression model describing the relationship between a binary dependent variable and a set of independent variables (explanatory factors). The explanatory factors used in this study included relative relief, mean annual precipitation, vegetation coverage, fault zones, lithology, soil type, GDP growth rate, industry type, and population density. The dependent variable used in this study was the presence (1) or absence (0) of casualty events caused by landslides in the county. For the logistic regression analysis, the continuous variables of relative relief, mean annual precipitation, vegetation coverage, GDP growth rate, and population density were substituted into the model. The categorical variables of fault zones, lithology, soil type, and industry type were transformed into binary dummy variables and then substituted into the model. The Probability Model of Casualty Events Caused by Landslide in China (CELC) was built based on the logistic regression analysis, and the confusion matrix and the receiver operating characteristic (ROC) curve were applied to assess the model performance. The results showed that all explanatory variables in the model were selected based on a significance level of 0.05. The coefficients of the explanatory variables showed that relative relief, GDP growth rate, mean annual precipitation, fault zones, and population density have a positive effect on casualty events caused by landslides. In contrast, vegetation coverage has a negative influence on casualty events caused by landslides. More specifically, the results showed that in terms of the influence degree of casualty events caused by landslides, the GDP growth rate ranks only second to relative relief. The probability of occurrence of casualty events caused by landslides will be 2.706 times that of the previous probability with an increase of GDP growth rate of 2.72%. In the evaluation of the model performance, the correct percentage in the confusion matrix is 75 % and the area under the ROC curve (AUC) is 0.826, revealing that the CELC model has good predictive ability. The CELC model was then applied to calculate the occurrence probability of casualty events caused by landslides for each county in China. The results showed that there are 27 counties with high occurrence probability but zero casualty events caused by landslides. The 27 counties can be divided into three categories: poverty-stricken counties, mineral-rich counties, and realty-overexploited counties, which are the key areas where great emphasis should be placed on landslides risk reduction.

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    Geographic Information
    Development and practice of Chinese Geographical andResource Journals cluster service platform
    ZHU Xiaohua,HE Shujin,YUAN Lihua
    2017, 72 (5):  918-941.  doi: 10.11821/dlxb201705012
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    The cluster development of academic journals has become an international trend. Foreign publishing groups have long retained the dominant position in sci-tech periodicals, while the cluster development of Chinese sci-tech periodicals is still at the initial stage. After the continuous efforts of nearly a decade to actively and creatively respond to the development opportunities and challenges of foreign and domestic journals, since 2006, Chinese geographical and recourse journals and their staff have basically completed the strategic development planning of Chinese geographical and resource journals cluster service platform and successfully launched 14 outstanding multiple value-added journal products include a cluster service platform site (www.geores.com.cn) with 54 joined journal and comprehensive module functions, a unified online editing system, the structurization of underlying data, rich media publishing, mobile phone APP and the WeChat service public number, data publishing, scientific cloud assistant system, media publicity and promotion, authoritative expert database of geography and resources in China, Chinese geographical conference service system, Chinese Geographical Editing and Publishing Annual Conference, the occasional thematic journal salon, China Geographical and Resources State Express policy and popular science edition, excellent papers of influential Chinese geographical journals etc. With clear business ideas, bold action, solid and orderly work, complete cluster function and high input-output ratio, the realization of two fundamental transformations have been promoted greatly, which is the Chinese Geographical and Resources Journals publishing from the traditional paper to the rich media, and from the literature producer to the academic and social integrated knowledge service platform, thus the Chinese Geographical and Resources Journals have further taken the initiative, grasped the opportunities, and opened a new situation and a new era of the cluster development.

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