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  • 1998 Volume 18 Issue 1
    Published: 20 January 1998
      
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  • PEDOGEOCHEMISTRY OF CHINA AND ITS SIGNIFICANCE IN AGRICULTURE
    Gong Zitong, Huang Biao, Ouyang Tao
    1998, 18(1): 1-9. https://doi.org/10.13249/j.cnki.sgs.1998.01.1
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    Pedogeochemistry in China is affected by the factors such as bio climate, parent material, topography and human activities, forming the various geochemical types, including clastic soils, saline soils, gypsic soils, carbonate soils, siallic soils, ferrallic soils and ferrolysed soils, and the spatial distribution of soil geochemical regions which include saline, carbonate, siallic and ferrallic regions from northwestern to southeastern China. The different pedogeochemical type has its own different element abundance that depends on the spatial distribution of soil types. In the saline soil region, available Na, K, B, F, and Cu in soils are rich, but available P, Zn, Fe, Mn and I are deficient. sixty three percent of the region are deficient in P, 80% in Zn and Mn, and 50% in Fe. In the carbonate soil region, available K and B are still rich, but available Zn, Fe, Mn, Mo, I and Se are deficient. On the basis of statistics, about 60% of the region are deficient in P, and 80% in Zn, Mn, Fe and Mo. In the siallic soil region, deficiency of K, B and F is gradually evident, but the area of deficiency in Zn, Mn, Fe, and I decreases. Thirty two percent of the region is deficient in K, and 47% in P. In the ferrallic soil region, available K, B, Mo and F are lack due to strong leaching, on the contrary, available Zn, Mn, Fe in the region are more sufficient than those in the other regions. The toxic of Fe and Mn in some soils even appears. Fouty six percent of this region is inadequate in P, 60% in K, and 90% in B, Mo and F. In a word, the availability of elements are affected by pH, Eh and fertilizing activity besides the states of elements. On the basis of the soil geochemical distribution and types, rational plantation, application of fertilizer to soil types and rational utilization of soil nutrition will be of great significance in raising the yield and improving the quality of agricultural products. Authors suggest that fertilizers be utilized on the basis of soil geochemical characteristics, types, pH, Eh and special necessity of plants.
  • CULTIVATED LAND RESOURCES AND DEVELOPMENT IN THE TROPIC AND SUBTROPIC MOUNTAIN AREAS OF SOUTH CHINA——A Case Study in Deqing
    Zhu Gongwu, Liu Ruihua
    1998, 18(1): 10-15. https://doi.org/10.13249/j.cnki.sgs.1998.01.10
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    Deqing is located in the tropic and subtropic mountain Area of China. Its area of Cultivated land from land use survey is 40% larger than the statistic. Of all cultivated land, owing to the flood, waterlogging, drought and barren soil, the high yield land occupys only 30%, and the mid low yield land 70%, which is far more than the percent statistic. These situations generally existed in tropic and subtropic mountain areas of South China. So the measures to protect the high yield cultivated land strictly, to improve parts of the mid low yield selectively, to adjust agricaltural structure further, and to control soil erosion, are necessary to make best use of its advantages and bypass the disadvantages.
  • HYDROCHEMICAL INDEXES OF SEAWATER INTRUSION AND COMPREHENSIVE JUDGEMENT ON INTRUSIVE DEGREE
    Zhao Jian
    1998, 18(1): 16-24. https://doi.org/10.13249/j.cnki.sgs.1998.01.16
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    The paper discusses the use of fiver hydrochemical indexes in evaluating the seawater intrusion, and ranking the intrusion degree for Cl-, M, Br-, rHCO3/rCl and SAR. The fuzzy mathematical comprehensive judgement model has been adopted as the method of adjustment. Based on more than 300 water samples obtained from four typical profiles in the coastal region of the Laizhou Gulf, during the period from June 1993 to June 1995, we made a comprehensive judgement of seawater intrusion degree.
  • A RESEARCH ON THE COMPLEXITY OF NATURAL DISASTERS
    Wei Yiming
    1998, 18(1): 25-31. https://doi.org/10.13249/j.cnki.sgs.1998.01.25
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    From the view point of system of natural disasters, some features of this system are described, a new concept of the complexity of natural disasters is put forward. On the basis of some research achievements in natural disasters, the application of fractal dimension and chaos, artificial neural network,as well as the comprehensive technology with qualitative and quantitative integration to the study on the complexity of natural disasters are discussed. Through the study on the complexity of natural disasters, the process of investigation on the whole behaviour of natural disasters will get a promotion.
  • HORQIN SANDY AREA DYNAMIC RESEARCH BASED ON THE THEMATIC CARTOGRAPHIC DATA BASE SYSTEM
    Zhao Yongping, Xu Bin, Huang Fang, Wang Yimou
    1998, 18(1): 33-38. https://doi.org/10.13249/j.cnki.sgs.1998.01.33
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    A quantitative research on Horqin sandy area dynamic evolution has been done for more than thirty years, based on the thematic cartographic data base system of Horqin typic sandy area which has been established by themselves. Influenced by human activities the desertification developed very fast from the 1950’s to the 1970’s, and faster than before the 1970’s to the 1990’s. If reducing human interference or with the help of the people, the eco environment would be recovered again. And the research result will have an important effect on the general improvement and the eco environment recovery of Horqin sandy area.
  • THE PROBLEM ABOUT THE RIVER SILT DELIVERY RATIO IN SOUTH SHAANXI
    Wu Chengji, Gan Zhimao
    1998, 18(1): 39-44. https://doi.org/10.13249/j.cnki.sgs.1998.01.39
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    This paper analyses the present situation of river silt delivery ratio, the delivery ratio change in time and space, and the development trend in South Shaanxi, indicates that under the spesific physical geography conditions, the tractional load ratio in the silt is rather great and it made the delivery ratio of this district less than 1. This is a very important character of river silt migration in South Shaanxi; the delivery ratio has an obvious difference in space; generally, it gets bigger along the river flow; considering the time, it has had the trend of decrease since the fifties, and in the coming days, with the decrease of river silt runoff volume and the manmade erosion worsening in this district, the silt delivery ratio will decrease further.
  • A STUDY ON THE CHARACTERISTIC OF WIND AND TEMPERATURE OVER THE ROOFTOP AND THE GROUND IN URBAN AREA
    Zhang Yiping, Peng Guifen, Zhang Qingping
    1998, 18(1): 45-52. https://doi.org/10.13249/j.cnki.sgs.1998.01.45
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    The microclimatic observation was conducted over the rooftop and the ground in urban and suburban areas of Kunming City of P.R.China. The main results obtained in this paper are summarized as follows: 1. The wind speed over the rooftop and the ground in the suburban are larger than in the urban area, and in daytime the differences are markable. 2. The air temperatures over the ground in the urban area are higher than in the suburban area at majority times. At night the differences are larger, the maximum is 2.7℃(at 7:00). Because the influences of different factors, in the same day the urban heat island appear, the urban cold island may appear too. 3. The variation of the urban heat island in rooftop is different from that on the ground. The maximum appears 14:00 of fine day. The mechanism responsible for urban heat island is the differences in the rooftop and on the ground. 4. The air temperatures over the rooftop are larger than over the ground. That expressed that the rooftop is the second thermodynamic surface in the urban area. There exist differences of vertical variations of the air temperature in the urban and suburban areas. 5. Because the position and the character of surface and the sky condition are different over the rooftop and on the ground in the urban and the suburban areas, the characteristics of the urban climate are different.
  • STUDIES ON ORIGIN OF THE LATE PLEISTOCENE STIFF CLAYS AT THE YANGTZE DELTA
    Chen Qingqiang, Li Congxian
    1998, 18(1): 53-57. https://doi.org/10.13249/j.cnki.sgs.1998.01.53
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    The stiff clays beneath the Holocene strata at the Yangtze Delta are considered to be paleosols by their subaerial pedogenesis characteristics, such as cutans, cracks and microcracks, plant roots and debris, etc. The paleosol sections, which are more than 2.0 meter thick, contain several clay accumulation layers, however, the sections are lack of caliche. Foraminifera occurs in paleosols of more than half of the study cores. Magnetic susceptibilities of the paleosol sections are low and lack of distinct fluctuations, and the magnetic fabric parameters alternate within a wide scope. The above characteristics of the paleosol sections suggest that the parent materials of the paleosols are of flood plain deposits, and the paleosols are the results of successive deposition and continuing pedogenesis on flood plain.
  • RESARCH ON THE PHYSICAL GEOGRAPHICAL BACKGROUND OF THE CULTURE OF TRADITIONAL CHINESE RESIDENTIAL ARCHITECTURE
    Sha Run
    1998, 18(1): 58-64. https://doi.org/10.13249/j.cnki.sgs.1998.01.58
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    This thesis discusses the influence of such physical geographical factors as climate, landforms and hydrology, geology and vegetation on the general layout, forms, styles and features of traditional Chinese residential architecture. Furthermore, analysis on the basis of it hase been made to find out the view of the nature of traditional Chinese residential architecture with the connotative views of utility, aesthetic perception and ecology.
  • TIME GEOGRAPHY: ITS ORIGIN, KEY CONCEPTS AND APPLICATIONS
    Chai Yanwei
    1998, 18(1): 65-72. https://doi.org/10.13249/j.cnki.sgs.1998.01.65
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    Time geography was originally developed by Swedish geographer, Torsten Hgerstrand and his associates at the Lund University, which first applied study using time geographical approach was a computer simulation model of daily activity programmes in urban planning. After a briefly explanation of the points at issues in time geography, this paper introduces time geography’s key concepts such as path, prism and constrain, and stressly reviews its various applications. Before the end of the 1970s, time geography was applied mainly to the studies of to regional planning, human environment relationship and social history along Hägerstrand’s basic viewpoint, but since entering the 1980s time-geographical approach have been extended to various fields such as the research of relationship between individual behavior and social structure, gender geography, warfare geography and urban area study, etc.
  • STUDY ON METHOD OF QUANTITATIVE ASSESSMENT OF FRAGILE ENVIRONMENT
    Zhao Yuelong, Zhang Lingjuan
    1998, 18(1): 73-79. https://doi.org/10.13249/j.cnki.sgs.1998.01.73
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    In this paper, a set of index and method on assessment of fragile environment are separately established. This is a systematic, complete, objective and flexible method of assessment of fragile environment. And it is easily used in practice. At last, its practicality and accuary are tested by using it to assess fragile degree of environment within 26 provinces of China.
  • CHARACTERISTICS OF THE URBAN AIR POLLUTION IN CHANGCHUN
    Li Wenbo, Zhai Guihua, Su Hongshi, Hu Xingda, Wang Tongyan, Du Zhaozhong, Song Zichun, Zhao Limin
    1998, 18(1): 80-87. https://doi.org/10.13249/j.cnki.sgs.1998.01.80
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    This article makes a detailed study of changes in geomorphologic landscape with the guide of air pollution meteorology. The article discusses changes in the area of city for surface roughness. That leads to changes in atmospheric boundary layer that form special wind field and temperature field in the districts of the city. The phenomenon of thermal is land and calm has changed the districts of atmospheric environmental capacity for pollutants. There is a trend of worse pollution in some districts. All these provide a scientific basis and aim at policy for making plans of city’s development and measures aginst air pollution in the future.
  • SIMULATED STUDY ON BARCHAN DUNE FORMS
    Ling Yuquan, Wu Zheng, Liu Shaozhong, Li Changzhi
    1998, 18(1): 88-93. https://doi.org/10.13249/j.cnki.sgs.1998.01.88
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    Barchan dunes is a fundamental pattern of aeolian landform. Generally speaking, it is moulded by non saturated wind-sand flow which is the high concentration. Its fomating process is caused by the wave grain duality of sand grain movement, and develop with two stages: sand material accumulation(high concentration saturated wind-sand flow)and form moulding(high concentration non saturated wind-sand flow), which shows the increase of dissipation and the decrease of dispersion. The scattered single barchan dunes on the non sand bed possess movability and form unstability except the high large crescent sand mountain. In wind tunnel, the formation of crescent dune form(its size is bigger one order of magnitudes than the ripples on the sand bed)will be helpful to understand the formation mechanism of the barchan dunes.