首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
1 INTRODUCTIONInrecentyearstheecoenvironmentoftheChangjiangRiverbasinsufferedfromseveredestruction,sedimentcontentintheriverwatergreatlyincreased,thedownstreamcoursewasseriouslysiltedupandfloodcontrolcapacitywasweakened.Thesimilarsituationalsooccu…  相似文献   

2.
The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in Chi-na. Rail, road and water transportation have competed against each other for container transportation in the Chang-jiang River main line and its delta area. It is of significance to assess these different transportation modes scientifi-cally in order to organize container transportation efficiently in this area and make decision for integral plan and construction of transportation system in this area. This paper outlines application of fuzzy comprehensive evaluation to appraise different modes of typical direction of containers. Twelve assessment indexes were decided. Membership functions were formulated. Evaluation results indicated that road transportation was optimal mode in the Changjiang River delta area, however water transportation was the primary way in the Changjiang River main line.  相似文献   

3.
We established a budget model of nitrogen (N) inputs and outputs between watersheds and waterbodies to determine the sources of riverine N in the Changjiang (Yangtze) River drainage area. Nitrogen inputs in the budget included N from synthetic fertilizer, biological fixation by leguminous and other crops, wet/dry atmospheric deposition, excreta from humans and animals, and crop residues. The total N input was estimated to be 17.6 Tg, of which 20% or 3.5 Tg N was transported into waterbodies. Of the total N transported into waterbodies, the largest proportion was N from animal waste (26%), followed by N from atmospheric wet/dry deposition (25%), synthetic fertilizer N (17%), N in sewage wastes (17%), N in human waste from rural areas (6%) and industrial wastewater N (9%). We studied the spatial patterns of N inputs and outputs by dividing the Changjiang River drainage area into four sub-basins, from upstream to downstream: the Tongtian River drainage area (TTD, the headwater drainage area, 138 000 km 2 , less disturbed by human activities); the Jinsha River drainage area (JSD, 347 000 km 2 , less disturbed by human activities, approx. 3 500 km upstream of the Changjiang estuary); the Pingshan-Yichang drainage area (PYD, 520 500 km 2 , large-scale human disturbance, about 2 000 km upstream of the Changjiang estuary); and the Yichang-Datong drainage area (YDD, 699 900 km 2 , large-scale human disturbance, approx. 620 km upstream of the Changjiang estuary). The average N input into waterbodies was 2.3, 7.3, 24.1, and 28.2 kg N/ha in the TTD, JSD, PYD, and YDD sub-basins, respectively, suggesting an increase of N-components of more than 10 times from upstream to downstream areas.  相似文献   

4.
Using neutron activation analysis method we determined contents of rare-earth and radioactive elements (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Cs, Rb, Sb, Sc, Sr, Ba, U, Th) in source water system of the Changjiang (Yangtze) River, which is mainly composed of the Tuotuo River, the Chumaer River, and the Buqu River. The contents of these elements in the unflltered water have a great variation and a close correlation with the water turbidity. The contents of these elements in filtered water only have a little variation and are lower than those in the unflltered water. The variations in contents of these elements in sediments are also very little. These elements in the unifiltered water are in geometric distribution, except Sc. Most of the elements in sediments are in arithmetic distribution, but Cs, Sb, Th, are in deviation distribution. The contents of most of these elements in the river source area correspond to the contents of fresh water of the earth. Most of these elements have a little variation in their c  相似文献   

5.
The results of water sample analyses and investigation in the head area of the Changjiang River reveal that the characteristics of hydrochemistry of the river vary with drainage basins. In the drainage basin of the Tuotuo River, the mineral concentration of water is generally high, ions of Cl and Na are obviously dominant. The water tends to be salty, and the type of hydrochemistry is rather complex. In the drainage basin of the Dam River, the mineral concentration is mainly in a low and middle level, ions of HCO3- and Ca2 are higher than others, and the type of hydrochemistry is relatively simple. The ground water in deep layers plays an important role in recharging surface water, and the stable recharging results in little change in chemical composition of surface water.  相似文献   

6.
This paper presents a paleoflood study to determine the flood frequency of the Changjiang River, based on core cj0702, taken from the Changjiang River subaqueous delta. We identified flood deposits by means of high-resolution grain-size variation, sensitive population, geochemical indexes and magnetic susceptibility. The core covers a time span of 120 years by 210 Pb dating and was sampled at 1–2 cm intervals. Grain size, geochemical elements, and physical parameters were analyzed. The results indicate that the sediment of the core is mainly composed of silt and clay, as well as groups of interbedded silt, clay silt, and clay. Vertically, the grain size pattern was controlled by seasonal variations in water discharge and by the sediment input in winter from the abandoned Huanghe River delta. River flooding caused extreme values in all our measured parameters. We identified more than 20 flood events that occurred since 1887 using the physical parameter analysis method. The environmentally sensitive component of sediment grain size(14.32–96.39 μm) contribution30%, Zr/Rb ratio1.5, and magnetic susceptibility16 were selected as the criteria for flood identification generally. We also found that floods that had taken place in the upstream, midstream, or downstream parts of the river were clearly identified by these indexes while the large-scale floods that covered the whole drainage area did not leave clear indications in the sediment record. This study for identification of flood events is of great significance for understanding hyperpycnal current sedimentation as well as for forecasting of floods.  相似文献   

7.
The Chinese people began to research the main source of the Changjiang (Yangtze) River 2,400 years ago. Limited by the scientific level, they did not discover it. The Tuotuo River was determined as the main source of the Changjiang River in the 1970s. However, this was not correct, because when comparing the length of the Tuotuo River with the Dam River, the glacier length at the headwaters was added to the Tuotuo River, resulting in that the Tuotuo River is 1 km longer than the Dam River, keeping in mind that the glacier can not be regarded as part of the river. In the summer of 1986, we investigated the source of the Changjiang River, we accurately measured the length of both the Tuotuo and Dam rivers, we discovered that the Dam River was 353.1 km long, and the Tuotuo River was 346.3 km long, the Dam River thus being 6.8 km longer than the Tuotuo River. The discharge of the Dam River is 196.18 m3/sec., 2.6 times as large as that of the Tuotuo River, that of the Tuotuo River is 75.10 m3/ sec. The drainage area of the Dam River is 1.8 times as larger as that of the Tuotuo River; the drainage area of the Dam River is 30,715.7 km2, the Tuotuo River is 16,691.0 km2. Through synthetic analysis of the factors mentioned above, we came to the conclusion that the main source of the Changjiang River is the Dam River instead of the Tuotuo River.  相似文献   

8.
1 INTRODUCTION The Ussuri / Wusuli River watershed is located in the southeast part of Heilongjiang Province of China, which joins remote regions of Russia. The watershed consists of approximately 26 000 000 ha, which is about two thirds of the watershed ecosystem in Russia, one  third in China. The Ussuri River forms part of the border between Russia and China, the shared border stretches more than 1100 km. Khanka/Xingkai Lake lies within both China and Russia. Its total area …  相似文献   

9.
Duringthefloodperiodof1998,someregionsofChinasufferedseriousfloodingandwaterlogging.EspeciallyintheChangjiangRiver,thewholebasinfloodonceemergedin1954occurredagain,andthemostseverefloodinthehistoryalsoemergedintheSonghuaRiverandtheNenjiangRiver,whicharousedmuchattentionacrossthewholecountry.Accordingtoincompletestatistics,till22ndofAugust,29provinces,autonomousregionsandmunicipalitieshadbeenaffectedbythefloodsinvaryingdegrees.ZI.2millionhaoflandwereinundated,223millionPeOPlewereaffeCted,3…  相似文献   

10.
According to the analysis of grain size, mineral composition and inclusion in quartz grain of the suspended and bed load sampled from the Changjiang (Yangtze) River and the Huanghe (Yellow) River, the authors reveal the differentiation of loads between the two rivers. In the Huanghe River the size of suspended load is coarser than that in the Changjiang River, while the bed load is on the contrary. Through heavy mineral analysis, the biotite content of the Huanghe River loads is much higher than that of the Changjiang River, and the monomorillonite content of the former is about two times higher than the latter. All those may be attributed to the effects of different material sources and hydraulic conditions on load. The analysis of inclusion in quartz grain definitely illustrates the environmental difference of material sources between the two rivers. In the meantime, it provides a new method in seeking source of river load. Subsidized by the National Natural Science Foundation. This paper is attributed to careful guidance from Prof. Wang Ying & Prof. Shi Yunliang.  相似文献   

11.
I.GRAINSIZEOFLOAD1.GrainSizeofLoadfromtheHuangheRiverThesuspendedloadsampledfromtheHuangheRivermainlycomprisessiltwhoseconten...  相似文献   

12.
REGIONAL DIFFERENCES OF ECONOMIC DEVELOPMENT OF THE CHANGJIANG RIVER VALLEY ChenGuoJie(陈国阶)(ChengduInstituteofMountainDisaste...  相似文献   

13.
Based on the theory of geo-economy, under the new situation of global economy, information network and China‘s entry into WTO, also with the holding of APEC (in 2001) and the International Exposition in the near future, the Changjiang (Yangtze) River Delta is striding toward the spectacular international multi-polar situation and becomes one of core regions with high-speed development. Facing the ocean and world all along, leading the progressive tides of the age and scintillating the splendor of the nation, she does advance with time. Through a long period of irrigation projects construction and intensive operation of lands in previous agricultural society, the artificial wetland ecosystem with a positive cycle had ever been formed in this region. At present, environmental pollution and urban expansion resulted from post-industrialization are being rectified. The delta will be the paradigm of industrial and agricultural modernization along the sustainable development road. With the rapid development of urbanization,she has been one of the regions with the highest density population and high urbanization level. Taking the Changjiang River estuary and the Hangzhou Bay as two parts, she is continuously strengthening and adjusting her interior structure, expanding mothball space and constructing the oriental modem ″logistics center“ to link the whole world. The butterfly-style urban system of the Changjiang River Delta is flying, probably engendering earthshaking “butterfly effect“.  相似文献   

14.
RELATIVITY AND SUSTAINABLE DEVELOPMENT   总被引:4,自引:0,他引:4  
From the realism of science, and taking the guide of EINSTEIN‘s Relativity as guide, this article called in question the present theory of the sustainable development by the rational thinking of philosophy and a close logic inference. It is found that there are many paradoxes to the theory. Through more deepening and meticulous inference, we arrived at philosophic language of science about the sustainable development. The sustainable development is “non-sustainable development”, and the non-sustainable development is “the best sustainable development”. While carrying out philosophical principle thinking and repeating science demonstration for the sustainable development, this article got further confirmation that the existence of human being at the minimum environment cost may help them obtain motive power of the sustainable development. In fact, this foundation motive power exists in the flow of development in different organization levels, meanwhile it exists in strategy of intuition living of the ancient people. Only in relative lower environment cost to live can we get the support system of science for the sustainable develooment, and be able really to achieve the basic goal of the sustainable development.  相似文献   

15.
According to historical records, there are 264 drought and flood years, occurred in the upper and middle reaches of the Changjiang (Yangtze) River during last 1020 years from 961 to 1980. The evolutionary law and developing trend of drought and flood years are studied. The distribution of drought and flood years are non-uniform and the dry and flood seasons in a year are concentrated. At the angle of monsoon circulation, at present the climate in the upper and middle reaches of the Changjiang River is just in the late stage of frequent drought period and the early stage of least flood period. In addition, the cycle of drought and flood and the feature of drought and flood occurred in the upper, middle and lower reaches of the Changjiang River are analyzed. It shows that the short period less than 10 years is in the majority, and the drought and flood occurred most frequently in the middle and lower reaches of the Changjiang River.  相似文献   

16.
Investigations from August, 1985 to July , 1986 showed that the high concentration area of PO4-P , SiO3-Si and NO3-N gradually reduced with the reduction of the area of the Changjiang River diluted water from summer, autumn to winter , and that the seasonal distributions and variations of the nutrients concentrations were mainly controlled by the river flow and were also related to the growth and decline of phytoplankton . The conservation of SiO3-Si and NO3-N in the estuary in the flood season was poorer than that in the dry season .. The behaviour of PO4-P in the estuary shows that aside from -biological removal, buffering of PCU-P is possible in the estuary . The highest monthly average concentrations and annual average concentrations in the river mouth were respectively 0.88 and 0.57 umol/L for PO4-P,191.5 and 96.2 umol/L for SiO3-Si, and 81.6 and 58.6 umol/L for NOs-N . The Changjiang's annual transports of PO4-P , SiO3-Si and NO3-N to the sea were about 1.4×104tons , 204.4×104 tons and 63.6×104  相似文献   

17.
1 Introduction Economic development in any country or region entails a long process of structural change in production as GDP and income per capita rise. In addition, economic de- velopment requires a long period of structural transfor- mation in materials inputs through reallocating natural resources (Cipolla, 1962). Land, as a crucial element and a key factor of production, is always the best witness of such transformations. In China, one of the largest countries in the world, 13.5% of its…  相似文献   

18.
TheimportantgUidingprinciplethatenstiresthesustainabledevelOPmentOfChinais"The21stCentury'sAgendaofChina"(Office,1994).ThesustainabledevelopmentintheareasalongthenewEtirasiancontinentalBridge(sectioninXinjiang)belongstooneoftheprioritemsof"theagenda".TheopeningofthenewEtirasiancontinentalBridgenotonlybringsabbotgreatoPPOrtunitiesfordevelopmentofXinjiang,butalsoplaysamajorroleinreducingthegapbetweentheWesternandeasternpartsofChina.Furthermore,itcantriggerfuttiresustainabledevelOPmentin…  相似文献   

19.
We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary. The average numbers of Synechococcus spp.(Syn) and picoeukaryotes(Euk) were(2.7 ±5.1) ×103 and(1.1±1.4) ×103 cells m L-1, respectively. Prochlorococcus spp.(Pro) was only found in the high-salinity brackish water with the concentration of 3.0×103 cells m L-1. Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk. The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean. The response of different picophytoplankton groups to environmental variables was different. Water temperature was more important in its control over Euk than over Syn, while nutrients were more important in their influence over Syn than over Euk. Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient(i.e., freshwater zone with 0-5 range, fresh and saline water mixing zone with 5-20 range, and high-salinity brackish water zone with 20-32 range), where three different phytoplankton communities were discovered, suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.  相似文献   

20.
The general trend of three elements (precipitation, runoff and evaporation) of the water balance of the Changjiang River Basin is discussed from the regional distribution of the mean annual values of view, i.e. isogram. The distribution of precipitation is non-uniform. The distribution of runoff mainly supplied from precipitation is more uniform than that of precipitation. The distribution of the evaporation from land is much more uniform than that of precipitation and runoff. Time distribution of these three elements shows the characteristics of comparatively distinct yearly variation and few variation between years. The relationship between precipitation and runoff, and between precipitation and evaporation in the humid region in the Changjiang River is analyzed. The slopes of their straight line correlation are nearly equal. The internal relationship between variables should be paid attention to, otherwise, a pseudo correlation may be resulted in. The paper provides the method of quantitative computa  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号