Loading...

Table of Content

    15 June 1993, Volume 12 Issue 2 Previous Issue    Next Issue
    EFFECT OF GLOBAL CLIMATIC WARMING ON THE EROSION AND SEDIMENT YIELD ON THE LOESS PLATEAU
    Jing Ke, Li Fengxin
    1993, 12 (2):  1-8.  doi: 10.11821/yj1993020001
    Abstract ( 622 )   PDF (630KB) ( 611 )   Save
    For the recent years,the erosion and sediment yield on the Loess Plateau tend to decrease obviously,as a result of the periodical reduction in precipitatior.Starting from the condition of global climatic warming in the future,this paper discusses the tendency of variation in the erosion and sediment yield on the Loess Plateau,Based on the correlation between the variations in erosion and climate in history,it has been identified that both the strong erosion and the deposition occurred during dry periods Because of the oncoming global climatic warming,the Loess Plateau will go into a wetter period,with an increasing precipitation.Consequently,the cover of vegetation will increase,leading to a reduction in erosion and sediment yield.ue to a limited environmental capacity and an over-laden population,the erosion and sediment yield will still remain at the present level
    Related Articles | Metrics
    THE STUDIES ON SEDIMENT TRANSPORT MODE AND ITS APPLICATION IN THE OUJIANG RIVER ESTUARY
    Zhu Yongkang, Sun Zhilin
    1993, 12 (2):  9-18.  doi: 10.11821/yj1993020002
    Abstract ( 586 )   PDF (745KB) ( 575 )   Save
    In view of the general character of several mountainous macrotidal estuaries in the provinces of Zhejiang and Fujian,the authors try to probe both the universal law of sediment transport and,the control means in estuaries of this kind by the monographic research on the Oujiang River estuary.The methods for geography and river mechanics as well as s'edimen-tology are applied to the detailed analysis of sedimentation in the estuary on three aspects.(1) a relation between the formation of an estuary and the sediment transport.(2) sediment from the river basin and its transport modes.(3) sediment from the adjacent coastal waters and its characteristics of transport by the tidal current.The basic conclusions are as follows.1.The coarse sediment grains larger than 0.1 mm ill size are widely distributed in the estuarine channel,among which the gravel particles move downstream by way of bed load and deposit in the upper estuary while the sand particles,except some inlaid in the gravel deposits as well as a small amount moved as bed load and tongued eastward in the Wenzhou Bay,are largely transported in such ways as either rolling and saltation or suspension into the lower estuary during flood season.In dry season the sand particles move there and back as bed load by the tidal current in the main channel.2.According to quantitative analysis on the measured data,the amount of coarse sediments from the Oujiang River basin every year,approxmiately 780 000 tons is much less than that of erosion and deposition in the estuary,several millions of tons.This shows that the movement of sand particles on local estuarine bed is the main causes for erosion and deposition of the estuary,and thus should be considered emphatically in the estuarine regulation.3.Transported in suspension,the fine sediment grains less than 0.1mm in size are mostly derived from the adjacent coastal waters besides a little from the Oujiang River.An obvious feature of suspended sediment transport is the presence of a turbidity maximum which migrates to and from with the tidal current.The maximum distance of shift is about 18 km.4.Because the coarse sediment differs fro the fine in the laws for transportation and deposition,it is suggested that the different control principles of both sediments should be adopted for the estuarine regulation
    Related Articles | Metrics
    ON THE TERRESTRIAL STRUCTURE AND TYPE OF INDUSTRIAL REGIONS
    Liang Rencai
    1993, 12 (2):  19-26.  doi: 10.11821/yj1993020003
    Abstract ( 521 )   PDF (636KB) ( 464 )   Save
    Terrestrial structure of industrial regions reflects the spatial features of industrial regions and their combination situation and proportion.It has taken shape progressively in the process of exploiting and using natural resources and advantageous location.Different industrial regions have different characteristics in terrestrial structure with the difference ot their birth setting,developing stage,aggregated industrial types and scale.Based 011 the feature of the terrestrial structure formation of industrial regions,the terrestrial types of industrial regions may be classified into the following five types,the urban type;the mining area type;the junction-combination type;the grouping type and the network type industrial district.The first three types are the urbanized industrial districts,and the last two the regional.Generally,the development and evolution of terrestrial structure of industrial regions proceed from point to area,from one level to multiple levels,from one group to multiple groups.Its movement direction and development velocity follow the smallest Resistance Law,i.e.the structure could firstly advance towards the smallest resistance direction with the fastest speed.
    Related Articles | Metrics
    THE RELATIONSHIPS BETWEEN SELENIUM AND ITS RELEVANT ELEMENTS IN ECOLOGICAL ENVIRONMENT AND KESHAN DISEASE IN SHANDONG PROVINCE
    Zhu Wenyu, Li Ribang, Wang Wuyi, Zhao Yuanwei, Tan Jianan, Wang Weizhong
    1993, 12 (2):  27-36.  doi: 10.11821/yj1993020004
    Abstract ( 607 )   PDF (714KB) ( 440 )   Save
    Keshan disease is mainly distributed in the compound area of Brown earth and Drab soil in lower mountains and hills of middle south Shandong province.Its feature of the chemical ecological environment in affected area is trace element deficiency.Especially,Selenium deficiency is common.With the comparative investigation between 1976 and 1987 in the same area,it was indicated that the decreasing incidence of Keshan disease was related closely with the increasing Se content in human body in recent years.Because the intake of Se contents of the inbatitants in Keshan disease area have increased with the improvement of their foods composition since early 1980's,the Se contents in the hair of the people in affected area have the same trend of increase.Through the present study,also it was shown that besides low content of Se,there were high contents of Mn,V,etc.from the environmental substances to human body.So these elements should be considered as the combinative factors for the compound cause of Keshan distease.
    Related Articles | Metrics
    THE INTER-EFFECTS BETWEEN RIVER GEOMETRY AND FLOW AND SEDIMENT TRANSPORT AND ITS SIMULATING APPROACH
    Liang Zhiyong, Zeng Qinghua, Zhou Wenhao
    1993, 12 (2):  37-46.  doi: 10.11821/yj1993020005
    Abstract ( 476 )   PDF (2691KB) ( 655 )   Save
    Based on the researches of the field data of the Lower Yellow River,the inter-effects between channel geometry and flow and sediment transport have been analysed and two patterns of scour-fill changes in river bends and straight reaches have been suggested.The effects of channel geometry on flow and sediment transport could be estimated through the following eqationsin which are usually not equal to unity,The narrower the cross-section is,the higher the values of β and α.The role of flow and sediment transport on cross section could be considered by eqs.(27) to (30).
    Related Articles | Metrics
    ENVIRONMENTAL CHANGE OF INLAND-TYPE CLIMATE DURING THE LATE PERIOD OF LATE-PLEISTOCENE IN NORTHERN XINJIANG
    Han Shuti, Wu Naiqi, Li Zhizhong
    1993, 12 (2):  47-54.  doi: 10.11821/yj1993020006
    Abstract ( 682 )   PDF (2618KB) ( 482 )   Save
    In this paper,based on using sedimentary profile,i.e.,representative Hole A and combining the age-determination date,we have synthetically studied the various environmental elements of Balikun lake in northern Xjnjiang.Then we have gained the sedimentary environmental signs that fit in with the biological,physical and chemical processes in arid land,which confirmed that the environmental change of Balikun Lake has evolved in the climatic pattern of alternating between cold-wet and warm-dry.In other words,the environmental change in this region acted upon the inland-type climate since the late period of late-pleistocene.Owing to the influence of the special geographic position and inner-outer factors of climatic system,fluctuating intensity,range and period of the inland-type climate have displayed the regional difference in time-space distribution,which constitute the change model of inland-type climate.The result mentioned above provides the new evidence for regional study jn globe change.
    Related Articles | Metrics
    A METHOD OF ESTIMATION OF EVAPORATION FROM WATER SURFACE
    Hong Jialian, Fu Guobin
    1993, 12 (2):  55-62.  doi: 10.11821/yj1993020007
    Abstract ( 722 )   PDF (534KB) ( 1404 )   Save
    Based on the similarity theory,this paper points out a new method jn which free convection and forced convection are taken into account in the estimation of water surface evaporation.To compare the estimated water surface evaporation by the model with observed water surface evaporation in Yucheng Experimental Station,CAS,we get that the average estimated evaporation value is about 5.1% less than that of the observed and the average relative error is 13.2%.The coefficient between estimated water surface evaporation value and observed value reaches 0.928,which illustrates the model has a high precision and is likely advis able for application.Finally,the authors copmare the model with some famous water surface evaporation's formula at home and abroad.
    Related Articles | Metrics
    FLOOD DISASTER SURVEILLANCE AND EVALUATION BY REMOTE SENSING
    Zhou Chenghu
    1993, 12 (2):  63-68.  doi: 10.11821/yj1993020008
    Abstract ( 620 )   PDF (416KB) ( 936 )   Save
    Flood hazard is one of the major natural hazards which threaten mankind.Besides the flood control construction,it is also important to the disaster deduction to establish a flood monitoring system.This paper focused on the application of Landsat satellite,meteorological satellite and air-born side-looking radar to flood disaster investigation and evaluation.Based on the analysis of the thematic flood information characteristics of the remotely sensed data,flood inundation area calculation model was developed.This model included digital image processing sub-model,water boundary extraction sub-model,flooding-area calculation sub-model and flood mapping sub-model.The last part of the papsr showed a successful application of the technology to the investigation and evaluation of "the 1991's flooding in Taihu basin.
    Related Articles | Metrics
    CHEMICAL SPECIATIQN AND CHARACTERS OF DISTRIBUTION OF HEAVY METALS IN GLACIER, RIVER AND LAKE WATER IN URUMQI AREA
    Chen Xibao, Zhang Shen, Tang Yijian
    1993, 12 (2):  69-76.  doi: 10.11821/yj1993020009
    Abstract ( 704 )   PDF (598KB) ( 687 )   Save
    The background values and chemical speciation of copper,lead,zine and cadmium in glacier,river,and lake water in Urumqi area were studied with a view to develop water resources in Xinjiang area as well as evaluating of water quality.The ice and water samples collected from the upper,middle and low reaches of Urumqi River and lakes were filtrated through 0.45μm membrance and determined by means of ASV technique The main results obtained are as follows.1.The total content levels of heavy mstals in some snow ice waters were in the order of old ice from No.1 glacier>fresh ice from the same glacier >snow ice water from this glacier>fresh ice from ths Bogeda mountain peak.2.The contents(Mt and Ms)of Cd,Zn,Pb and Cu in the Urumqi Ri ver from Wangfeng to Wulopo Reservoir were all within the range of the background values of these elements in the world fresh water.3.Due to the dry and cold natural environments,the Cd,Zn,Pb and Cu in the above water of the Urumqi River mainly existed as dissolved forms,and most dissolved Cd,Zn and Pb were present as ASV labile,only most dissolved Cu was ia the bound forms.4.With the thick anions complsxing,the significant fractions of total heavy metals in Chaiwobao Lake and Salt Lake water were in dissolved forms,except that significant percentage of Cu in Salt Lake water was in suspended forms,while for the four dissolved elements,their bound forms concentrations were all higner than corresponding labile.
    Related Articles | Metrics
    A PRELIMINARY RESEARCH ON THE MODEL EXPERIMENTS OF THE RISK RANGE OF DEBRIS FAN
    Liu Xilin, Zhang Songlin, Tang Chuan, Cheng Ming
    1993, 12 (2):  77-85.  doi: 10.11821/yj1993020010
    Abstract ( 593 )   PDF (681KB) ( 711 )   Save
    By the way of small-scale model experiments of debris flow in the Jiangjia gou,Dongchuan City of Yunnan Province,five groups of 68 times of standard experiments have been conducted,and the results have given the relationships among the maximum length,width,thickness,risk range of debris fan and the supply modes of debris flow (continuous and intermittent supply),gradients of depositional area and flow section as well as unit weights of debris flow.Under the specific experimental parameters,four types of the formulae to calculate the risk range of debris fan are presented.The important conclusions are as follows,1.Under the circumstance of the continuous accumulation of debris flow,the relationships between the maximum length,width and the risk range of debris fan and the total sediment of debris flow are positively related,and can be expressed as the natural logarithmic functions.The relationship between the maximum length of debris fan and the total sediment of debris flow is positively related,too,aad can be expressed as the linear function,2,Under the condition of the intermittent supply of debris flow,the relationships between the maximum leng th,width,risk range of debris fan and a debris flow supply are positive linear funtions,while the relationship between the thickness of debris fan and a debris flow supply is not close.3 The relationships between the maximum length,risk range of debris fan and the gradients of depositional area are positive linear function The relationships between the maximum width,thickness of debris fan and the gradients of depositional arer are negtiye liaear functions.4,No matter how the unit weight and supply of debris flow are,the maximum length,width,thickness and risk range of debris fan all have a stochastic relationship with the gradients of flow section of debris flow,5,The relationships between the maximum length,risk range of debris fan and the unit weight of debris flow are nsgatively related,and can be written as the natural logarithmic functions.The relationship between the maximum thickness of debris fan and the unit weight of debris flow is positively related,and can be written as a linear function,The maximum width of debris fan and the unit weight of debris flow have not a good relationship.
    Related Articles | Metrics
    AN APPROACH TO THE AGRICULTURAL STRUCTURE READJUSTMENT IN THE LOW MOUNTAIN-HILL REGION OF THE SUBTROPICAL ZONE IN CHINA-TAKING THE REGION OF SOUTHERN YIXING CITY AS AN EXAMPLE
    He Xiang
    1993, 12 (2):  86-93.  doi: 10.11821/yj1993020011
    Abstract ( 435 )   PDF (561KB) ( 460 )   Save
    The research in this article shows that.The quantitative classification method can be applied to the research about the areal agricultural structure readjustment.Meanwhile,it is of great importance when drawing up a scheme to study the areal land type structure,the present areal agricultural structure and problems accompanying with land use.And based on the research,several profitable conclusions are drawn out at last.
    Related Articles | Metrics
    REVIEW ON THE STUDY OF SANDY DESERTIFICATION AMD ITS PROSPECT
    Dong Yuxiang, Liu YiHua
    1993, 12 (2):  94-102.  doi: 10.11821/yj1993020012
    Abstract ( 536 )   PDF (780KB) ( 612 )   Save
    Sandy desertification is one of the most important problems in China,the study of sandy desertification has become one important topic in recent years because of its immense harmfulness This paper looked back on the developing pro-cess of the study on sandy desertification,reviewed its study on the historical,modern,physical and reverse process of sandy desertification,analised the points in debate of some basic problems such as the definition and the causes of the sandy desertification,discussed the new trends and some problems in study This paper also gave the main topics of sandy desertificantion lately.
    Related Articles | Metrics
Share: