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    15 January 1996, Volume 51 Issue 1 Previous Issue    Next Issue
    AREAL ASSOCIATION OF NATURAL HAZARD IN CHINA
    Li Bingyuan, Li Juzhang, Wang Jianjun
    1996, 51 (1):  1-11.  doi: 10.11821/xb199601001
    Abstract ( )   PDF (732KB) ( )   Save
    By analyzing disaster forming mechanism.natural hazards in China can be divided into 20 basic types according to direct factors causing disasters, in which drought, waterlogging, flood, earthquake, landslide and debris are the most serious in China.The macrolandform,especially the three grand relief terraces in China, and the macrolandform-dominated regionalization of natural environment affect the distribution of flood, waterlogging, landslide, debris and earthquake.The difference in natural hazard distribution can reflect the regularities of areal association of natural hazards. The regionalization of disasters should abide by not only geographic principles, but also the principles of similarity and difference in the main types of natural hazards. By analyzing the areal differentiation of Chinese main natural hazards and the intensity of factors inducing disasters based on the Chinese data bases of intensities of the main factors inducing disasters and the data bases of social environment, and using ARC/INFO GIS. the authors compiled distribution maps of Chinese main natural hazards and maps of intensity of factors inducing disasters. Results show that Chinese natural hazards can be divided into 3 regions and 12 subregions.I. Severe hazard region in monsoon plain and mountain in east China This region is located west of seas and controlled by monsoon. The intensity and frequency of drought, waterlogging and flood in the area are the highest in China under the influences of abnormality of monsoon, typhoon and cold wave, and exclusive hazards of oceanic genesis appear here.Microtherm, earthquake, landslide and debris are serious. The area includes seven subregions: I1 Moderate hazard subregion of waterlogging. flood, microtherm and biological hazards in northeast China; I2 Severe hazard subregion of drought. waterlogging. flood and earthquake in the plain in east China. I3 Severe hazard subregion of waterlogging. flood and draught in the middle Changjing River, I4 Severe hazard subregion of waterlogging, flood, drought and earthquake in the southeast coastal area; I5 Severe and moderate hazard subregion of drought, soil erosion and earthquake in the Loess Plateau; I6 Severe hazard subregion of drought, waterlogging, flood, landslide and debris in Sichuan, Guizhou, Hunan and west Hubei; I7 Severe hazard subregion of earthquake. landslide and debris in Yunnan and west Sichuan.Ⅱ. Moderate hazard region in mountain and basin in dry northwest China This area lies in the inland with dry climate, strong wind and frequent sandstorm. and there is no rainfed agriculture. The main natural hazards are earthquake. flood, drought and windstorm.The area includes three subregions: Ⅱ1 Moderate and slight hazard subregion of drought, heavy snow and forest fire in Inner Mongolia: Ⅱ2 Moderate hazard subregion of earthquake, sandstorm,flood and drought in Xingjiang and Gansu; Ⅱ3 Moderate hazard subregion of earthquake. landslide and debris in the Tianshan Mt. in Xinjian Ⅲ. Slight hazard region in the cold Qinghai-Tibet Plateau Tectonic movement in the region is strong. Earthquake, collapse. debris and heavy snow are intense, but the losses population. This region includes two subregions: Ⅲ1 Moderate hazard subregion of earthquake, landslide and debris in the southeast Qinghai-Tibet Plateau; Ⅲ2 Slight hazard subregion of earthquake and heavy snow in the northwest Qinghai-Tibet Plateau.
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    AN OBJECT-ORIENTED MODEL OF ELECTRONIC MAP DESIGNING:A STUDY ON THE SOFTWARE FOR THE NATIONAL ECONOMIC ATLAS OF CHINA (ELECTRONIC VERSION)
    Chu Shiqiang, Liu Yue
    1996, 51 (1):  12-24.  doi: 10.11821/xb199601002
    Abstract ( )   PDF (711KB) ( )   Save
    With the development of computer-aided cartography (CAC) incorporating geographic information system (GIS), electronic mapping system has taken on a new look with rich interactive and analytical abilities. This paper presents an object-oriented model for electronic map designing, and describes its implementing techniques systematically.On the basis of a thorough analysis of a number of cartographic works, such as the National Economic Atlas of China, adopting the object-oriented method, the author provides a conceptual model of electronic maps by abstracting two classes: "map class" and "map layer class" (Fig. 1).Each map has a main topic (usually described with the map name), and this topic may be divided into several sub-topics (themes) including a base map and thematic contents. Each theme is represented by a certain symbolization method with a specific legend, which can be taken as a kind of object "layer". Thus. a map can be considered as an organic entity, named "map object’, which consists of the map name, the mathematical basis, map layers and the relationships among them.The map class should include a series of function members for map designing, editing. querying and analyzing, thematic data and figure output, etc. And thus, a conceptual model of electronic map can be deduced.Going a step further, the author summarizes a numbers of thematic map symbolization methods for economic and social phenomena, and establishes a library of computerized models of thematic symbols, such as "pie" graph, "bar" graph, "percent proportion table" graph, "population pyramid" graph. Based on those above, the author creates a model for electronic map designing, and sets up a series of mapping "templates". With these templates, map features can be visualized automatically with cartographers’ own styles. In addition, a group of essential software resources invoked in mapping templates, such as the map symbol library. the map color library, the method library for cartographic index classification, the symbol-scale building tool, the data capture dynamic linking library (DLL) and the object linking and embedding (OLE) tool, are introduced.Developed in accordance with the strategy mentioned above, the software package MapMagic can produce multimedia electronic maps efficiently and has been successfully used in editing and compiling the Electronic Version National Economic Atlas of China. Through practice, it has been proved that MapMagic, as a thematic mapping software for general purposes, is a qualified method of editing & compiling a variety of electronic maps on social, economic, or natural phenomena.
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    THE FEATURES OF MEAN WIND STRESS FIELD IN THE PACIFIC OCEAN
    Li Kerang, Lin Xianchao, Wu Zhongxiang
    1996, 51 (1):  25-32.  doi: 10.11821/xb199601003
    Abstract ( )   PDF (478KB) ( )   Save
    By using the wind data derived from COADS, of which the mesb is 5白5癮nd the average period is from 1949 to 1987, monthly mean wind stress in the Pacific Ocean is calculated. For determining the wind stress, bulk aerodynamic formula is used in which the drag coefficient is represented by a second degree polynomial, considering the effect of wind speed and stability. The drag coefficient depending on wind speed and stability, which is proposed by Bunker, is selected for analysis. The results show this method is quite good for its precision and convience.In this paper, the zonal and meridional wind stess for each latitude zone and the distributions of wind stress field in January, April, July and October are analyzed. distribution of wind stress corresponds with planetary wind system on the whole. Walker cell in equatorial area and seasonal variation of monsoon circulation in the west Pacific have an obvious impact on the variation of wind stress. There are some asymmetries in the mean zonal wind stress of both hemispheres. Wind stress intensity of midlatitude westerlies is weaker in the northern hemisphere than in the southern hemisphere, and it is opposite in the tropical trades.In the northern hemisphere, in January, the zero line of zonal wind stress is at about 28癗. To the north of this line, the zonal wind stress is positive where the ocean gets momentum from the air.To the south of this line up to the 32癝. the zonal wind stress is negative where the air gets momentum from the ocean. Along the equatorial zone of the west Pacific between 0? 12癝, momentum flux is transferred from air to ocean. In July. trade-wind moves northward. The zero line of zonal wind stress is at about 40癗 in the northern hemisphere and is at about 31癝 in the southern hemisphere.The momentum flux is positive in the summer monsoon regions.The value of longitudinal wind stress is much lower than that of latitudinal wind stress. In January, the dominant wind in the subtropical and tropical north Pacific is from northeast. The meridional wind stress is negative whiers the ocean gets momentum from the dir. Along the east and south coast of Asia continent, the strong northeast monsoon results in a band which has maximum values of meridional wind stress. In July. the wind stress in the east Pacific of northern hemisphere is negative. In the west Pacific, the momentum flux is positive with a maximum in the south China sea and its adjecent seas related to the southwest and southeast monsoon there.
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    VARIATIONS OF THE ANTARCTIC SEA ICE AND POLAR VORTEX INDEX IN SOUTHERN HEMISPHERE AND THEIR RELATIONSHIPS
    Bian Lingen, Lu Longhua, Jia Pengqun
    1996, 51 (1):  33-43.  doi: 10.11821/xb199601004
    Abstract ( )   PDF (617KB) ( )   Save
    In this paper Cluster Analysis was used for grouping the similar regions of the variability of the Antarctic sea ice, and five regions were obtained based on the Antarctic sea ice extent data of 17 year period (1973--1989). The indices of the polar vortex area and the intensity in southern hemisphere were calculated using of 500hPa monthly mean data in the same period.The analysis of the features of temporal and spatial variations of the Antarctic sea ice and polar vortex as well as their relationships is presented by using statistic analysis. The results show that the discrepancy of climatic characteristics and interannual variability of the sea ice and polar vortex are obvious. They oscillate with cycles of 2 2. 5 years and 5 7 years over most of the regions. The linear trend of the sea ice anomaly reveals that 4 of the 5 regions exhibit a trend of reducing sea ice.The trends of the polar vortex coverage anomaly for all regions are negative similar to that of sea ice, while the corresponding trends of polar vortex intensity are predominantly positive over 3 regions. The above statistical facts is consistent with the effect of global warming.Cross-correlations among concurrent anomalies of the variables are most signifcant from the Southeast Pacific area (e. g., Antarctic Peninsula, region 5) to the South Atlantic area (region 1 ). Lag correlations between them are also closer to the sea ice leading the polar vortex cover and lagging the polar vortex intensity in region 1. The correlations are larger with the sea ice lagging both of the cover and intensity of the polar vortexm in region 5.
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    THE SPATIAL DIVISION OF INDUSTRIAL ACTIVITIES IN THE PEARL RIVER DELTA
    Ouyang Nanjlang
    1996, 51 (1):  44-50.  doi: 10.11821/xb199601005
    Abstract ( )   PDF (284KB) ( )   Save
    The article analysed the spatial division of industry of the Pearl River Delta (PRD) in the context of rapid industrialization both in urban and rural area since the implementation of reform and open-door policy. Industrial output value of 39 industrial sectors of counties and urban districts in 1990 are used. Location coefficient and index of specialization are used to measure the extent of specialization of a spatial unit and its status in the region.The research revealed that the PRD is characterized by its advanced and high-tech industris in Guangdong and China and that the spatial division of industry has been emerging. Most of the cities and counties in PRD have at least 5 sectors in which the location coefficient are larger thanl, and the percentage of uuangzhou’s industrial output value in PRD has droped from more than 50% in 1980 to 23.68% in 1990. This demonstrates that the specialized activities in PRD have no longer been concentrated in Guangzhou.However, the key problem is that a number of the counties/cities in PRD lack highly specialized activities and have similar industrial structure. When measured by using the index of specialization,those counties/cities often have low values. The paper points out that lack of competition from other regions, diversified investment sources and interest groups, decenteralization in economic administration in PRD and weakening of provincial government control/guidance are the reasons contributing to the above problems.To perfect industrial spatial division and to promote industry development in PRD, Guangzhou and Shenzhen should be developed as the industrial innovation centres of PRD. Places outside Guangzhou and Shenzhen should concentrate their industries in only several activities. Government intervening is necessary as integrated development has become an essential issue in PRD.
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    IMPACT ASSESSMENT OF WIND ON LAKE’ S FLOW PAGATION IN EAST DONGTING LAKE, HUNAN, CHINA
    Wu Bingfang, Shen Liangbiao, Zhu Guangxi
    1996, 51 (1):  51-58.  doi: 10.11821/xb199601006
    Abstract ( )   PDF (326KB) ( )   Save
    Lake’ s flow was studied thorourghly and many effective analysis methods were developed both at home and abroad.In areas where flood risk is high, researches on lake flow patterns and the effect of wind on lake water depth are very important in respects of design of flood prevention projects, selectlon of flood prevention creterla, management and maintainance of flood prevention projects and utilization and conservation of wetland in the area. There are many factors reponsible for the lake flow, inc0uding energy, depth of lake water, the roughness of lake bottom and the environment around the lake. Comprehensively taking all these factors into consideration, the paper makes a quantitative analysis on the change pattern of lake flow by means of a two dimensional unsteady flow model with the assistance geographical information system.The lake’s flow propagation model, with the Saint-Venant equations of two dimensional unsteady shallow water, was developed for East Dongting Lake, Hunan Provlnce, China. The model’s parameters(e. g. ground elevation and roughness coefficience). were retrieved from geographic information system, which made the software compacted and universal. The model was used to analyze the lake’s flow motion and assess the impact of wind on flow. The results Indicate that the wind force has an important influence on flow but it is modified by elevation, natural environment, roughness. The water level will be increased by 30.1cm when wind velocity is increased from 6m/s to 12m/s. Following results are got in the study: (1) The geographical information systems has introduced a solution to the probems of selection of model parameters in the analysis of large area lake flow motion. Geographical in formation systems make the processing of model boundary conditions and popularization of the model easy and convenient. (2) The methods adopted in the paper are capable of representing the pattrns of lake flow and the impacts of wind on lake flow. The methods can be used to simulate the process of lake flow motion, to evduate the food prevention function of wetlands(weed land, counter-wave forest) and to identify the sensitive area to wind. (3) Among the so many factors that affect lake flow,the lake bed,the shape of lakeshore and the wind are the most influential factors affecting the patterns of lake flow motion. (4)Further anabsls on the impacts of weed and counter-wave forest on lake flow should be made on the basis of the present research.
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    A PRELIMINARY STUDY ON THE PALEOENVIRONMENT OF THE MIDDLE HOLOCENE IN THE HULU RIVER AREA IN GANSU PROVINCE AND ITS EFFECTS ON HUMAN ACTIVITY
    Mo Duowen, Li Fei, Li Shuicheng, Kong Zhaochen
    1996, 51 (1):  59-69.  doi: 10.11821/xb199601007
    Abstract ( )   PDF (669KB) ( )   Save
    Hulu River drainage area is located in eastern Gansu and southern Ningxia, which is west of Lupan Mountain in middle Loess Plateau. The middle Holocene strata were well developed on the first terrace of the Hulu River and its tributaries. The paleoenvironment is established by the analyses of sedimentary characteristics, clay minerals, carbonates and pollens in the deposits ors the terrace. The climate changes remarkablly affected the ancient civilization in the region.The early Holocene stratum can be seen at the bottom of the first terrace, which mainly consists of alluvial loessic deposits. The clay minerals are mainly illites and the pollens are mainly herbs,which shows a relatively dry and cool paleoclimate. There was no ancient civilization during this period in this region.The early-middle Holocene stratum lies in the lower part of the first terrace, which is mainly composed of alluvial and lacustrine silts and clay. The alluvial gravels can also be found in some places, which indicates a warm and humid paleoclimate. A climate change is found by the sedimentary analyses. It was the warmest and the most humid from 8 000 to 6 000 aBP. The contents of kaolinite and montmorillonite are high. The pollens indicates a wooded grassland or a forest flora of coniferous and broadleaf trees. The favourable natural conditions resulted in the appearances andrapidly development of ancient civilizations. The first stage of Dadiwan civilization (7 800- 7 300aBP) shows some relatively advanced characteristics with big ancient communities (based on the size of the sites), appearances of colourful pottery and agriculture. The early Yangshao civilization (6 800- 6 000 aBP) shows some developmental features. The communities were still big and the number of communities was increased. From 6 000- 5 000 aBP the clay mineral association and the pollen spectrum indicate a slighty dry and cool paleoclimate. The technology of production and pottery making of the middle and late Yangshao civilization during this period had some development, the number of ancient communities were also increased but the size of communities was not increased and some were even decreased.The late middle Holocene (about 5 000- 3 000 aBP) stratum mainly consisting of alluvial loessic silts lies in the upper part of the first terrace, representing a distinguish aggradation of loessic silts.The fact that the content of illite increased and the contents of the kaolinite and montmorillonite decreased and the pollen is mainly herbs indicates a drier and cooler paleoclimate. The number and the size of the communities of the Changshan civilization(4 800-4 200 aBP) decreased. Thete were some cave like residences. The technology of pottery makinghad some retrogradation. The communities of Qijia civilization(4 400-3 900 aBP) were widely distributed but the size of them were very small indicating that the civilized area increased but the production of per unit area decreased, and also the proportion of animal husbandry increased. The ancient civilization from 3 900-3 300 aBP has not been found out yet. The Shiwa civilization(about 3 000 aBP) was also very limited in scale. All of these are because of the deterioration of the paleoenvironments during this period.
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    AMELIORATING SALINE ALKALINE LAND BY INTENSIVE PUMPING AND IRRIGATION AND MAINTAINING ECOLOGICAL STABILITY
    Pang Chunhao, Cheng weixin, Li Yunsheng, Zhang Xingquan, Liu Enmin
    1996, 51 (1):  70-79.  doi: 10.11821/xb199601008
    Abstract ( )   PDF (585KB) ( )   Save
    Well irrigation and well drainage" was adopted to ameliorate saline-alkaline land in the 1960’s in Feng Qiu and Yucheng, and "pumping saline-water and suppling fresh water" was used to improve saline-alkaline land in the 1960’s in the northern part of China.On the bases of the specific conditions in Bei Qiu in Yucheng City, we adopted a method of intensive pumping and irrigation to ameliorate saline-alkaline land. The improvement is distinct, and the treatment period is shorter.After intensive pumping and irrigation, the ecological conditions can be long maintained by spreading manure, intertilling and loosening the soil, covering with crops at all seasons, salt content in the cultivated layer is less than 0. 2%, and crops grow very well for 4 years.It is clear that irrigation can leach salt of soil, spreading manure and nitertilling-loosenning the soil can improve root condition. Pumping saline water and Levelling of land can strengthen the improving effect.
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    THE STUDY ON SPATIAL LINKAGE BETWEEN THE SUPPLY AND DEMAND OF TOURISM
    Niu Yafei
    1996, 51 (1):  80-87.  doi: 10.11821/xb199601009
    Abstract ( )   PDF (526KB) ( )   Save
    Tourist market involves the supply market and demand market. It is significant to maintain the balance of tourist supply and demand. This paper discusses the law of regional distribution and dynamic balance of tourist supply and demand. The author also defines the spatial models of tourist supply and demand.First, based on case studies, a new concept, tourist threshold population, is defined. The threshold population size of a tourist destination is the population size of tourists visiting the destination when input of tourism is equal to output.Secondly, a demand model is given. From the demand model, we can understand easily why the tourism in metropolitan areas often bring higher income than in remote regions.From the supply and demand models, tourist destinations can be divided into four types and conclusions on the space linkages of tourist supply and demand in the four types are drawn. The four types are listed as follows:1. tourist destinations are located in the core cities of metropolitan areas;2. torist destinations are located in the suburbs or outskirts of metropolitan areas;3. tourist destination are located beyond metropolitan areas;4. tourist destinations are located in remote regions.In the first situation, the supply and demand of tourism are overlapping in space, and the marginal profit of tourism is the largest. When the distance between a tourist destination and a core city increases, the marginal profit of tourism decreases.
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