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    15 October 1982, Volume 37 Issue 4 Previous Issue    Next Issue
    PHYSICAL GEOGRAPHY AND AGRICULTURE
    Li Zhi-wu, Wu Bo-fu
    1982, 37 (4):  341-348.  doi: 10.11821/xb198204001
    Abstract ( )   PDF (617KB) ( )   Save
    Based on the relation between basic science and technology, this article intents to discuss why physical geography is a foundation of agricultural technology and one of its aims is to serve agriculture.- We mention that physical geography as a foundation of agriculture is in accordance with the following facts: 1) At present the way to raise agricultural yields other than to breed improved varieties is to improve the ecological conditions, expand the area under cultivation and rationally use of the land resources-all these are within the study scopes of physical geography. 2) Through the ages physical geography has played a supporting role in the improving of agricultural productions. Writings of physical geography such as "Yu Gong" in ancient times, and "Qi Min Yao Shu" later, in the history of China, are remarkable examples in this respect. After the foundation of new China in order to have a rapid advance in agricultural production, the party and comrade Mao Tse-tung worked out the famous measures "the Programme for Agricultural Development" and "the Eight point Charter for Agricuture" in both of which geographical conditions are placed in an outstanding. Today in carrying out construction of modern agriculture in our country, agricultural regionalization and balance of ecology should be based on. From what said above it shows that physical geography played an important part in agricultural production. 3) Besides productive requirement there are still enormous significance attached to the comprehensive character, regionalism and productiveness of physical geography. Today in developing agricultural production we should make sufficient use of natural resources of agriculture on one hand, protect natural resources and build good ecosystem on the other are also required. Entrusted with this very complicated mission if we want the mutual relation ship of natural elements to develop as man expected we have to approach the problems in accordance with the regularity of the changes of nature, the law of area differentiation and the patterns of various natural productiveness. It is natural to regard physical geography as a fundamental science as well as to believe its main aim is to serve the agriculture.In tackling the problem of how physical geography serves agricultural production, we suggest that natural regionalization and evaluation of landquality, overall plan of agricultural production and construct of fields with high and stable yields, in accordance with the law of materialization of scientific theories and the need for physical geography in production. These measures are: 1) able to meet the requirements in different stages of agricultural development, viz. requirements in stages of observation, planning and implementation, 2) conform to the processes of recognizing and utilizing natural environment by man, and 3) accord with the general law of materialization of scientific theories.
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    THE GEOMORPHOLOGICAL STRUCTURE OF THE YELLOWRIVER DELTA AND ITS EVOLUTION MODEL
    Ye Qing-chao
    1982, 37 (4):  349-363.  doi: 10.11821/xb198204002
    Abstract ( )   PDF (853KB) ( )   Save
    Due to the frequent shifting of its distributary mouth and displacempnt of its apexthe Yellow Kiver delta has a complex structure.1. The environment factors which influence the delta formation are:1) Sediment yield of the river basin2) Fluctuation of the sea-level3) Marine Dynamics4) Sea-bottom features5) Frequent shifting of the lower channel2. The geomorphological structure of the delta and their genesis1) The delta plain declines from southwest towards northeast with an averagegradint of 0.1-0.15 ‰ . It consists of distributary channels and bordering levees, com-posed of fine sands and silts with intervening depressions composed of fine clay and silts.The plain is formed as a result of frequent shiftings of the distributary channels. Since the latter are intensively aggraded and often breached at certain points, the amount of sediment deposited on the delta plain occupies about 20% of the oncoming sediment discharge of the Yellow Kiver.2) Undersea delta: It is the extension of the delta plain under the sea and spreads out towards the shallow sea in the from of a fan. Its average gradient is 0.8%0. It is formed in the flat and shallow off shore enrironment where tide and wave are both very weak. Here the water flow from the river is dispersed with a consequent decrease of flow velocity thus reducing its sediment carrying power both this fact and the floc-culation of fine sediments by saline water, lead to large amount of sedimentation in this area which attains 40% of the total oncoming load from the Yellow River.3) The river mouth bars: Checked by the tide, the sediment poured into the river mouth area is partly laid down to form a series of sand bars. Some of them stretch across the channel mouth as transverse mouth bars; some of them stretch along the channel as mid-channel bars; some of them lie beyond the channel mouth as offshore bars.3. The evolution model of the deltaThe evolution model of the Yellow River delta can be outlined as follow: two main stages of evolution have been recognized, the formation of the first major subdelta during 1889?934 with its apex at Ninghai and the formation of the second major subdelta during the period of 1934?980 with its apex of Yuwa. With each of thesetwo major subdelta, there are five tongue like minor subdelta. The evolution cycle for each major subdelta is about 50 years, while that for each minor subdelta about 7 years. These subdeltas of different scales and different ages are all overlapping one anather. This is revealed in vertical sections of the delta alluviums and deposits. Under the alluvium at the front of each subdelta lobe, a buried lens of marine deposits can often be found.4. The effect of the delta evolution on the upstream reaches of the river With the apex of the delta being relatively fixed. The surface of the delta has been raised with corresponding elevation of the river bed upstream from the delta area. This may be called the headward aggradation along the river, But whenever a shifting of the channel occurred or when there was abundant water in some the years, both downstream and heaklward degradation of short period would be found from the apex of the delta of that time. Successive rising of the river bed near Yuwa and their correspendiug headward aggradation were very remarkable during the period from 1969?973, besides, headward aggradation has also a close relation with the rising of the average sea-level. The coefficient of correlation is r=0.95 during 1970?1973. Judging from the adjustment of the long profile of the river and the distribution of D50 grain-size along the river. We find that the headward aggradation has almost reached near Lao Kou, about 262 Km upstream from the mouth.
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    PRELIMINARY STUDY OF THE BEIJING MICROTEKTITE
    Li Ding-rong, Wang An-de, Xie Zhenzhao, Wang Huan-zhen, Liu Qing-si
    1982, 37 (4):  364-371.  doi: 10.11821/xb198204003
    Abstract ( )   PDF (509KB) ( )   Save
    In the sumzner of 1979, the authors discovered more than 100 glass globules withniameters of 0.17-0.65 nun at a depth of 182--327 m from the eore of well No.1in Shunvi, Beijing, China. No trases of erosion are Wered on surface of theseglobules. The filaments on them are still perfectly clear, without any evidence oftransportation and resedimentation.Observed under microscope, most of these microtektites are globules like tadpolesand dumb-bells, generally with a smooth surface, a great many have prolongedfilaments, some of which are curved and twisted. They are generally yellowish or darkbrown in colour. Seen under orthopolariscope. they are substantially uniform. Therefraction index, as determined by immersion method, is 1.590-1.613. No crystalenclosures are found inside them, but there are a lot of blebs in them.Their chemical components (weight %), determind by the Electronic Probing Group, Uranium Geological Institute of Beijing, are: Si02, 37.25; Al2O3, 16.60; FeO, 0.47; MgO. 15.25; A12O3 CaO, 27.11; Na2O, micro; K20, 2.94; TiO, 0.08; and MnO, 0.85.According to their stratigraphic ages, occurrences, forms, physical properties andmain chemical components, we consider that they are microtektites.These microtektites are preserved in the middle and lower parts of Zhaili Forma-tion of the Mid-Pleistocene Series. Their lithoglass globules discovered in Beijing axedifferent from the known samples, either the glass meteorites (including tektitesof China), or the hay silica glass. By their forms and physical properties, they areobviously microtektite of high calcium and low silicon.Their absolute age, as determined by fission track dating, can provide an importantbasis for age determination and stratigraphic correlation of the Cainozoic strata, as wellas a new way for the study of the Quaternary Period.
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    ON THE SHANGHAI URBAN HEAT ISLAND EFFECT
    Chou Shu-zhen, Zhang Chao
    1982, 37 (4):  372-382.  doi: 10.11821/xb198204004
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    Shanghai is the biggest and most important industrial and commerical center inChina. Multiple observations show that the urban area is nearly always wanner. Forexample, on Dec. 13, 1979 at 8pm. (a calm dear night) the warmest temperature isotherms (8.5°) were associated with the highest density urban dwellings (fig 2). Some ave-rage records in the coldest temp., annual temp., the number of coldest days and hottestdays all indicated the urban heat effect as shown in table 1-2.The diurnal variation, annual variation and local difference of urban heat islandintensities for Shanghai were shown in fig. 4-5 and table 3-6 as examples.The urban heat island has a number of consequences. During the maximum deve-lopment of an urban heat island, the temperature field often induces a ’’ country breeze’’.There are more thunderstorm days, and heavy rainy days in Shanghai city comparedwith its nearby counties due to the rising current above the heat island. Except themean value of absolute humidity and relative humidity are lower, all the mean tempe-rature value of the coldest month, the hottest month and the annual are higher in urbandistricts compared to the rural areas in average, (table 7-8).
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    PRELIMINARY STUDY ON THE DEGREE AND TIME OFCONCENTRATION OF MONTHLY RUNOFF OFCHINESE STREAMS
    Tang Qi-cheng, Cheng Tian-wen, Li Xiu-yun
    1982, 37 (4):  383-393.  doi: 10.11821/xb198204005
    Abstract ( )   PDF (652KB) ( )   Save
    Taking runoff volume of time interval as a vector, the degree and time of con-centration can be resulted by means of vector composition. They are considered as arather new expression describing seasonal distribution of stream, runoff which can beperformed on the basis of different time intervals (day, month, season, etc.) in accor-dance with specific requirements. The resultant vector composition is a graph, takingmonthly runoff as time unit (Fig. 2 and 3).Degree of concentration represents the magnitude of concentration of monthly streamrunoff within twelve months. It is closely related with unequilibrium coefficient ofmonthly stream runoff (Fig. 1) but possesses a higher resolution than that of unequilib-rium coefficient. Time of concentration represents the most regulatable months in termsof accumulation of monthly stream runoff which, in most cases, are comparable to themonths regarding that with practically maximum values occured.Data of the hydrological stations (8,307 station-years in all) in China are selectedin this paper for calculation and illustration. Upon which isopleth maps of degree ofconcentration (Fig. 4) and time of concentration (Fig. 5) of stream-runoff in Chinahave been constructed. Analysis on the law of distribution of the above mentioned twomaps is thus carried out areally. Degree of concentration of stream runoff in Chinais comparatively high, it is especially so in northern part of China. If these runoffvolumes are sufficiently utilized, greater regulating reservoir capacity would be re-quired. Since degree of concentration of rivers in west China occurs in summer monthsit is necessary to prepare regulating reservoir capacity beforehand for flood preven-tion.
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    THE GEOCHEMICAL CHARACTERISTICS OF CHEMICALELEMENTS IN TROPICAL SOILs IN HAINAN ISLAND,CHINA
    Wang Jing-hua, Pan Shu-rong, Sun Jung-xin, Tu Shu-de, Qian Qin-fang, Wang Yu-ji, Chen Bing-ru
    1982, 37 (4):  394-406.  doi: 10.11821/xb198204006
    Abstract ( )   PDF (731KB) ( )   Save
    The Hainan Island is belonged to the tropical seasonal rain forest laterite zone. Thelatosol dominates this zone, but as an exception, there are also lateritic red soil, paddysoil, coastal solonchak and dry red soil. The mountain yellow soil is distributed at 900 mhigh mountainous region. The neutron activation method was used to determine thechemical elements of the soils in Hainan Island. 28 elements and A.B.C. three naturalgenetic horizons were analysed for each type of soil and the result illustrated as follows:1. The abundance of Cu, Zn, Ni, Co, As, Sr in tropical soils are very low whencompared with the soils of Northern China. The abundance of Cu is 14.3, As 7.30, Ni39.2, Co 9.03 ppm respectively. The abundance of Zr, Th and Fe are high than that ofNorthern China, they are 706.9. 40.6, and 4X104 ppm. This is due to the intense wea-thering and leaching of tropical regions.2. The abundance of rare elements and rare earth elements in lateritic red soilderived from granite are higher than the latosol which derived from basalt, for example,the abundance of Zr and La in latosol derived from granite are 1996.7 and 118.1 ppm.The parent material is an important factor.3. The rate of Zr/Hf from dry red soil, yellow soil, lateritic red soil to latosol arerespectively 31.8, 33.8, 42.3, 48.5. This illustrates the relatively light to heavy weatheringof the soil.4. The abundance of rare earth elements in soil are richer than that in chondrite.The abundance of Bu in the yellow soil, podzolic yellow soil and paddy soil and theabundance of Ce in the limestone red soil derived from limestone show a negative ano-maly.5. In eight samples, the total amount of abundance of eight rare earth elementsare 0.021%, in which Ce takes 41.3%.
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    THE VARIATION OF THERMAL INDEX WITHALTITUDES AND THE DIVISION OF VERTICAL-HORIZONTAL CLIMATIC ZONES OF THE SOUTHERNPART OF YUNNAN PROVINCE
    Lu De-kang, Chang Ke-ing
    1982, 37 (4):  407-420.  doi: 10.11821/xb198204007
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    The southern part of Yurman Province may be divided into three climatic zones:(1) tropical SW monsoon humid climatic zone (2) tropical SE monsoon humid climaticzone and (3) tropical central dry climatic zone, according to the general circulation ofthe atmosphere and topography. The eharateristics of thermal-moisture regimes of eachzones are quite different from one another, and the division lines of these three climaticzones are quite distinct and stable from year to year.The thermal regime of each of the above zone is mainly determined by the altitudeabove the sea level. As the data of meteorological stations located at valleys or basins.at different altitudes and different latitudes are analysed, six thermal belts can be drawnout which may be called the vertical-horizontal thermal belts. The division of these beltsshows both the characters of vertical spectrum and of horizontal zonality.The multiple varieties of climates corresponding to different altitudes in tropicalsouthern Yunnan are favourable in forming a rich and diversified biological resources,and production of tropical and subtropical crops.The system and classification of the climatic regioualization are proposed by theauthors as follows.0 grade: three climatic zone as mentioned above1st grade, six vertical-horizontal climatic belt2nd grade, sub-division according to moisture index3rd grade, sub-division according to overwintering conditions of vegetation.
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