Table of Content

    15 January 1979, Volume 34 Issue 1 Previous Issue    Next Issue
    Zheng Du, Zhang Rongzu, Yang Qinye
    1979, 34 (1):  1-11.  doi: 10.11821/xb197901001
    Abstract ( )   PDF (898KB) ( )   Save
    Very high elevation coupled with very vast extension as well as their accom-panying intense thermodynamic effects have made the Qinghai-Xizang Plateau a unique physical geographical region in the world, where natural conditions are very complicated and the horizontal zonation is closely correlated with vertical zonation.
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    Zhang Shen
    1979, 34 (1):  12-17.  doi: 10.11821/xb197901002
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    On the northern slopes of Mt. Qomolangma samples of ice and snow were collected at altitudes of 7,050-7,846 m. The trace elements in ice and snow samples were determined by neutron activation analysis in the Institute of High Energy Physics, Academia Sinica. The data obtained indicate that variation in the vertical distribution of trace elements in the ice-snow profiles does not differentiate greatly. The contents of Hg, Cu and Sb in glacial ice and snow collected in the nit. Qomolangma region are in agreement with those of the metals in snows of the Antarctics and Greenland. The contents of As and Cr in our samples are greater than those in ice and snow of the Antarctics. The zine content is high up to 0.42 ppm as comparable with that in precipitation in the USA. The order of enrichment factor valtues of trace elements (Cu, As, Cr, Sb and Hg) is similar to that of the Antarctics with the exception of zinc. There are probably natural sources for these trace elements, such as crustal weathering, volcanic eruption etc. yet the high enrichment factor may be due to some anthropogenic sources.
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    Wang Jiacheng, Wang Shanling, Qiu Guoqing
    1979, 34 (1):  18-32.  doi: 10.11821/xb197901003
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    The chief characteristics of the permafrost distributed along the Qinghai-Xizang Highway are discussed in this paper.The Qinghai-Xizang Plateau has the greatest area, lowest temperature and thickest permafrost in the middle-low latitudes of the world. The permafrost distributed and perched on this plateau occupies more than 60% of the total permafrost areas in our country.The distribution of the permafrost on this plateau depends chiefly on the elevation as well as the latitude and other geological and geographical factors.On this plateau, the solar radiation, which has an important effect on the heat balance of the ground surface, is so strong that the necessary conditions for the permafrost formation appear more strict than those in the high latitudes. The southern limit of the permafrost in the Da Hinggan Ling (Great Khingan) Region generallycoincides with the 0 - -1℃ isotherm of the annual mean air temperature, while alongthe Qingha-Xizang Highway, with the -2- -3℃.According to areal differentiation in the permafrost distribution, six regions may be recognized.Besides, in this paper we also analyze some of the distributive laws of underground ice and the cryogenic structure of the permafrost, recite several cryogenic phenomena and their distributive characteristics and briefly discuss the history of the permafrost development in this region.
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    Tang Maocang, Shen Zhibao, Chen Yonyu
    1979, 34 (1):  33-42.  doi: 10.11821/xb197901004
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    Studies on the mean pressure, wind and precipitation data over the Xizang Plateau and its neighbourhood reveal their climatic characteristics as follows:1.The Plateau has its own permanent pressure systems in the lower and middle troposphere, i.e., the cold high in winter (Nov.- March) and the heat low in summer (June-Sept.).2.In summer, the Xizang heat low is separated from the Indian monsoon depression by a so-called Southern Plateau high belt, its axis is almost paralleled to the Ximalaya range.On the northern slope of the Plateau, there is a high belt too, its axis with a slope about 1/200 dips toward the plateau proper.3.In winter, the Xizang cold high is separated from the Indian high by a Southern Plateau low belt, its position has shifting northward from the summer southern Plateau high belt and with a slope about 1/100 dipping toward the Plateau proper.4.The vertical distribution of the prevailing winds over the Xizang Plateau is distributed into three layers: the lower is the mountain-valley wind layer, with a thickness about 1 km; the middle is the plateau monsoon layer, with a thickness about 2? km over the margins of the Plateau and about 1 km over the Plateau proper; the upper is the plenetary circulation, under the control of the global atmospheric circulation.5.The plateau monsoon, is not a part of the Indian monsoon, there exist a distinguishable anticyclone belt in summer and a cyclone belt in winter between these two monsoon systems.The plateau monsoon is caused by the seasonal variation of the thermal effect on the Xizang Plateau.
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    Pu Jingjuan, Wang Changyao
    1979, 34 (1):  43-54.  doi: 10.11821/xb197901005
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    In order to grasp their dynamics, it is necessary to have some means to monitor their changes between short intervals. Remote sensing technique is an ideal one among these means- This article is an attempt to study the dynamics of some river deltas and lakes by means of Landsat-MSS imagery in combination with field observation and analysis of historical records.The Huang He Delta is fast prograding through the aggradation, shifting and lengthening of its numerous distributaries. It may be considered as the overlapping and coalescing of tens of small individual deltas which can be clearly delineated from the Landsat-MSS imagery. The development of the Chang Jiang Delta is somewhat different. Its channel mouth bar is the focus of the delta growth. The channel mouth bar first becomes an island and then gradually combines with the mainland as one of the passages around it, gradually silting up. So the river mouth island may be considered as a subdelta which will eventually be annexed to the main delta. It can be seen from the Landsat-MSS imagery that the annexation of the Chongming island to the main delta is impending as the passage north of it is silted up while the Changxing island at the mouth of the southern passage is becoming the site of a new subdelta. According to the Landsat-MSS imagery, the Luan He Delta has a strong tectonic control in its development.Along the middle and lower courses of the Chang Jiang River, there are several large lakes which are the resulting from the combined actions of exogenic and endo-genic forces. Among them the Poyang Lake and Dongting Lake are the largest two. The Poyang Lake is inundated by the Chang Jiang River during flood and is largely exposed at low water stage to be crossed by the extended Gan Jiang channel. The Dongting Lake is connected to the Chang Jiang River by four over flow channels which bring large amount of silt to the northern side of the lake. So the lake shrinksin area. The desert lake------Lop Nur has so far been famous as a wandering lake,but in fact it is not wandering. All evidences recealed on the Landsat-MSS imagery and collected in the field indicate that this lake is much affected by climatic fluctuations and neotectonic movements. It gradually shrinks and moves to the west but has never left its downfaulted basin.Landsat-MSS imagery will much promote our researches in various fields of geography and help to realize the ’quantification of geographical phenomena.
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    Wu Zhongxing
    1979, 34 (1):  55-68.  doi: 10.11821/xb197901006
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    The article presents two methods for deriving coordinates formulae for protective points, which are quite necessary for compiling computing programs when one kind of map projection, by computer operation, is transformed into another.
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