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  • 2006 Volume 26 Issue 3
    Published: 20 May 2006
      
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  • Spatial-temporal Changes of Urban Competitiveness in Urban Cluster of Pearl River Delta
    XU Xue-Qiang, Cheng Yu-Hong
    2006, 26(3): 257-265. https://doi.org/10.13249/j.cnki.sgs.2006.03.257
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    Since the 1990s, the modern technology develops very fast and Internet is applied extensively, the trend of economic globalization is more fast and deepen.City, as the main carrier of economy, is more and more important on the economic development whether in countries or regions scale.Simultaneously, the trend of urban competition in a group is arisen.The status of urban cluster is stand out increasingly in international competition.In urban competitiveness study from urban cluster, not only the main factors which urge urban competitiveness and the main support frame of urban competitiveness can be analyzed by comparing urban competitiveness from time-space in urban cluster, but also the theories and methods of urban competitiveness study can be enriched.This paper firstly sets up the Three Factors Concept model of urban competitiveness based on researching the dynamic characteristics of the meaning of urban competition and resolving the concept of competition.On this basis, this paper put the Zhujiang River Delta as a case and the evaluation indexes system of Zhujiang River Delta is designed.At last this paper uses the main factor method to estimate the urban competitiveness of nine cities of PRD from 1990 to 2001.The urban competitiveness and it's influence factors is analyzed and compared from Spatial-temporal change.
  • Assessment on Radiant Ability of Regional Central City—A Case Study of Zhengzhou City
    FENG De-Xian, JIA Jing, QIAO Xu-Ning
    2006, 26(3): 266-272. https://doi.org/10.13249/j.cnki.sgs.2006.03.266
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    Taking Zhengzhou as a case, this paper studies index system of radiant ability of regional central city and gives weights to indexes by AHP(analytical hierarchy process) method.Accordingly, the radiant scopes of different factors between Zhengzhou and other cities concerned are analyzed by using the theory of breaking point.As a regional central city, Zhengzhou's influential areas, advantages and disadvantage of developments are studied in this paper.Finally, the author gives the approaches and measures to strengthen the radiant ability of Zhengzhou.The conclusions are: 1) the comprehensive radiant ability of Zhengzhou shows stronger in the direction of SE-NW, and weaker N-S, which means that Zhengzhou is in a strong position in competiting with Hefei and Taiyuan, but in a weak position with Wuhan and Beijing-Tianjin areas.2) Zhengzhou is still a provincial central city, and its radiant ability as well as its influence is rather weak.The attractive ability to cities near the provincial boundary, such as Sanmenxia westwards, Xinyang, Nanyang, and Zhumadian southwards, is insufficient.Efforts should be made to realize the change from provincial central city to regional central city and central city of the big region.3) all factors of urban radiant ability is in the same level except that opening level is lower than provincial cities around Henan Province.The low level of opening not only restrains modulation and optimization of industrial structure and innovation of science and technology, but also influences cultural innovation, radiant ability, and especially, development of economy.4) Urban radiant ability includes other factors, such as politics and culture, besides factors mentioned above.Quantitive analysis and comparison have not been made due to difficulties of quantification of politics and culture.Urban political radiant ability can generally reach city's boundary of administration in current political system.At present, it is difficult to confirm the boundary of cultural radiant ability.This will be the goal of our near future.
  • Mode of Circular Economy in Region
    CI Fu-Yi, CHEN Lie
    2006, 26(3): 273-276. https://doi.org/10.13249/j.cnki.sgs.2006.03.273
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    Circular economy is a new economy in 21st century,with the harmonious development of Resources and environment, economy and society as its goal.Mode of circular economy is a new type of mode to promote sustainable development, so the study of regional circular economy mode should be strengthened in the geographical field.This paper discusses the five basic types of circular economy mode and their main characteristics.These five basic types of circular economy mode include mode of rising of both economic and environmental benefits; mode of rising of environmental benefits with economic benefits unchanged; mode of rising of environmental benefits with economic benefits declined and being over zero; mode of rising of environmental benefits with economic benefits declined and being zero, and mode of rising of environmental benefits with economic benefits declined and being under zero.It is pointed out that the reasonable types of circular economy mode among these five basic types of circular economy mode can be chosen if people understand their main characteristics.Only in this way can we have a sound grip of environmental, economic and social benefits of circular economy.It is argued that circular economy mode has spatial rules including the spatial difference rules, the "U" distribution rules of environmental quality and the inverse "U" distribution rules of the regional gap of environmental quality.It is also argued that it is not realistic to reduce the gap of environmental quality between the three economic regions in China in the near future and it is realistic to slow down the tendency of enlarging the gap of environmental quality between these three one in China through making the right choice among the five basic types of circular economy mode in the light of local conditions in the near future.The present study first discusses the types of circular economy mode which are suitable for China, studies how to construct enterprise clusters on apt types of circular economy mode, and proposes the concrete ways.The quantity of enterprise clusters on the apt types of circular economy mode should decline from the east economic region to the west one in China on the whole.This paper also states that enterprise clusters on the mode of rising of both economic and environmental benefits and the mode of rising of environmental benefits with economic benefits unchanged should be popularized, and that enterprise clusters on the mode of rising of environmental benefits with economic benefits declined but being over zero among the industries, which have severe pollution, should also be paid great attention to.Then, this paper analyses the constitution of the industrial system of regional circular economy and argues that environmental industry and retrieving and reusing industry should be developed in a big way, and the circle among industries and different parts of industries to optimize the regional industry structure should be strengthened.Finally, this paper displays the principles to choose leading industries, which should include scale principle, marketing potential principle, and comparative circular economic advantage principle.
  • Dynamic Change of Land-use Patterns in West Part of Songnen Plain
    LIU Dian-Wei, SONG Kai-Shan, WANG Dan-Dan, ZHANG Shu-Qing
    2006, 26(3): 277-283. https://doi.org/10.13249/j.cnki.sgs.2006.03.277
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    Songnen Plain is one of the commercial grain bases of China, which belongs to ecological fragile regions.Based on remote sensing and GIS technologies, the dynamic changes of land-use patterns in western Songnen Plain were analyzed quantitatively.The results show that great change has occurred in spatial pattern of land-use in the past 50 years.The area of cultivated land increased 29.65?104 ha, which mainly converted from grassland and wetland.And 70.29?104 ha of grassland lost in the past 50 years, except for conversion to cultivated land, desertification, salinization and grassland degradation can also account for grassland losing.Wetlands have decreased 62.45% since 1954.The study also indicated that the fragmentation of grassland, forestland, wetland and unused land were severe.The maximal patch area and maximal patch perimeter were all decreased.The conversion ratio of different land-use types were severe in the west part of Songnen Plain, which indicated that different land-use types were unstable, anthropogenic and natural factors both play important roles in this process, while human actives affect the process more severely.
  • Factor Analysis on Spatial Variation of Sustainable Utilization of Agricultural Water Resources
    HUANG Chu-Long, DENG Wei
    2006, 26(3): 284-291. https://doi.org/10.13249/j.cnki.sgs.2006.03.284
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    Agricultural Water Resources system is an intricate socio-economy ecosystem, thus, factors affecting Sustainable Utilization of Agricultural Water Resources (SUAWR) is complicated.Intricate connotation of SUAWR can only be assessed by applying indicators system(IS) properly.Being too many indicators in indicators system to assess SUAWR, it will be complicated due to information overlap of indicators.While, if deleting indicators at random, information reflecting SUAWR will be cut, and evaluation results will be wrong.Factor Analysis is a rather well method in reducing redundance information.The magistral information can be separated from numerous Factors effecting on SUAWR spatial variation by factor Analysis, thereby, analysis of spatial variation of SUAWR will be simplified.Study shows that spatial variation pattern of SUAWR in Northeast China displays as capacity of SUAWR decreasing inwards as an arc from North, Northeast and East on the whole.The dominant factors influencing the spatial variation pattern are water resources, ability of eco-environment reserving and accommodating water resources, and income from water resources use in Northeast China.The indicators reflecting the three dominant factors and being distinctly correlative to the spatial variation pattern are water resources quantity and crop season rainfall per hectare of tilth, gap between average annual rainfall and average annual evaporation, aridity index, runoff coefficient, the proportion of paddy field to tilth, rice yield per stere of irrigation water.According to SUAWR contribution of the 7 principal components retrieved from indicators system by factor analysis, the key of entire improvement of SUAWR of the whole evaluating area depends on adjustment of anthropogenic activities to lessen bad human impact on SUAWR.
  • A Prototype of Urban Simulation Model Based on the Theories and Methodologies of Cellular Automata (CA) and Multi-Agent System (MAS)
    LIU Miao-Long, CHEN Peng
    2006, 26(3): 292-298. https://doi.org/10.13249/j.cnki.sgs.2006.03.292
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    Faced upon the fact of relatively lagged development in urban simulation and modeling, the problems and inadequacies consisted in traditional urban simulation have been analyzed in this paper.This paper discussed the possibility using a lot of theories and methods originated from computational science, complex researches, geographic information science and geocomputation developed recently as the foundation of computational urban models.A prototype of computational urban simulation model, which integrated the activities on the macro-, meso- and micro-level scales, has been put forward based on the theories and methodologies of cellular automata and multi-agent system.The formation method and structure of a residential location choice model on the neighborhood scale, which as a base of the prototype, have been discussed conceptually.At last, the paper analyses the future development in the field of urban simulation and modeling.
  • Changes in Spatial and Temporal Distribution of Maize Sown Area and Its Causative Factors in Maize Belt of Jilin Province in Last 50 Years
    WANG Zong-Ming, YU Lei, ZHANG Bai, SONG Kai-Shan
    2006, 26(3): 299-305. https://doi.org/10.13249/j.cnki.sgs.2006.03.299
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    Maize belt of Jilin Province now is one of important bases for commodity food in China.The spatial and temporal distribution of maize-sowing have changed greatly in this area after the foundation of P.R.China in 1949.This paper studied the evolution process and the related driving factors of the changes to provide references for adjusting regional agricultural structure.The study showed that, the sown area of maize in maize belt of Jilin Province increased fluctuantly.It got the culmination in 1996, and descended from 1997.Our analysis showed that after the large-scale agricultural industry development in 1980, the gravity of sown area of maize moved eastwards.Among the driving forces, the policy induction, agricultural technology and comparative superiority over other crops were important driving forces.In addition, in recent years, it got warmer and this phenomena was more obvious in winter and spring.The sown area of maize in maize belt of Jilin Province took on the increasing trend along with the increased air temperature.
  • Basic Theories of Geo-Info-TUPU
    CHEN Yan, QI Qing-Wen, YANG Gui-Shan
    2006, 26(3): 306-310. https://doi.org/10.13249/j.cnki.sgs.2006.03.306
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    Geo-Info-TUPU was put forward firstly by a Chinese scientist during the 1990s.Based on plenty of materials, we concluded that Geo-Info-TUPU is resulted from the developments of the subjects and technologies including cartography, geo-info sciences and "3S", synchronously influenced by the combination of the imagination and the abstract thinking in the geography science.Based on the analysis of the Geo-Info-TUPU’s development process, we expatiated on the theories of the Geo-Info-TUPU, including the basic conception and character, research contents and objects, and the significance of the Geo-Info-TUPU, finally the prospects of the Geo-Info-TUPU was discussed.
  • Comprehensive Evaluation on Wetland Water System and Water Resources Management in the Jianghan Plain
    WANG Xue-Lei, LU Xian-Guo, REN Xian-You
    2006, 26(3): 311-315. https://doi.org/10.13249/j.cnki.sgs.2006.03.311
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    Water is the key factor to form the wetland ecosystem and also the most sensitive component in the wetland ecosystem and it plays an important role in the process of wetland.Wetland is an important ecosystem in the Jianghan Plain, in which water factor affects its structure and function.The Jianghan Plain is the typical region of subtropical wetland ecosystems of China, where there are many lakes and waterways, and the micro-physiognomy is very complex.The alluvial plain is a honeycomb of waterways bordered by natural levees, and the depressional areas encompassed by these waterways are dish-shaped in cross-section, distributing the wetland systems composed of river, lake, marsh, gleyed paddy soils and swamp paddy soils.And the hydrology relationship of the Yangtze River and lakes and rivers is complex and the water system includes water inputting and outputting system of wetland besides the wetland water system.The water resources are abundant in the Jianghan Plain, but precipitation is not even in spatial-temperal distribution and traveler-water volume is instability, which often the collection of water that cause flood and waterlog or the lack of water that cause drought.Wetlands in the Jianghan Plain play an important role in floodwater storage, water quality improvement, climate changes, biological diversity protection and eco-environment improvement.As a storage space for surface water, lakes reduce the risks from flood and waterlog.In generally, Jianghan lake group can accommodate more than 150?108m3 water volume in the year abundant in rain.Honghu Lake is a main lake of storage water in the Jianghan Plain, and acts as the function storing floodwater and irrigating cropland in the middle-low Four Lakes district in the Jianghan Plain.According to some simulation results, the largest storage water volume of Honghu Lake is about 21?108m3.As having a strong self-decontamination capacity, most lakes in the Jianghan Plain are moderate eutrophication.Based on probing into the structure and function of wetland water system in the Jianghan Plain, the approaches and strategies about water resources' reasonably utility and scientific water management are made.Firstly, water resources and environment should be protected actively.Secondly, lakes should be restored from impoldering in order to enhance the storage floodwater capacity of wetland in Jianghan Plain, and to reduce the loss resulted by flood and waterlog.The third, water environment security system should be set up.At last, wetland water management system in the Jianghan Plain should be included in the management and plan of the middle reaches or even the whole of Yangtze River drainage basin.
  • Primary Study on Catchment Space for Water
    YANG Bo, DENG Wei
    2006, 26(3): 316-320. https://doi.org/10.13249/j.cnki.sgs.2006.03.316
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    The catchment space for water, used as an expedient to apply water space theory at catchment scale, is one kind of space that encompasses river and its branches, linked lakes, wetlands and other kinds of water bodies, floodplains and partial slops that directly affected by flood, as well as the corresponding aquifer systems within these areas.Modification of catchment areas by human activity has led to dramatic changes in the flow of water.The overuse of land has destroyed lateral and vertical pathways taken by water draining to a stream, and disturbed runoff process and redistribution of rainfall, which has lowered water readjustment ability of lands within the catchment areas.As a result of human impact, hydrological function of water storage, water detention and groundwater recharge through lands within catchment area have been decreased, but meanwhile flood and drought disasters have been increased.These problems have been paid much more attention by hydrologists and ecologists recently.How to restore and protect hydrological functions of lands along river has become one of important aims in catchment management.Space for water, provided as one of solutions to achieve sustainable water resource use, puts emphasis on these spaces like wetlands, forests, lakes and floodplains and their important hydrological role of water cycle and their influence on sustainable utility of water resource.Through these analyses, the concept of the catchment space for water is provided, based on the concept of space for water, and the connotation, classification, boundary, measurement, structure and characteristics of catchment space for water are discussed.Framework of the study is then proposed, aiming at setting up theory frame of catchment space for water and providing theoretical instruction and technical support for integrated water and land management at catchment scale.
  • Discussion on "the Theory on Climate Cause of Peat Forming"
    YIN Shu-Bai, LU Xian-Guo
    2006, 26(3): 321-327. https://doi.org/10.13249/j.cnki.sgs.2006.03.321
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    Having specified the main viewpoints of "the theory on climate cause of peat forming", and based on the analysis on the peat definition and the essence of organism accumulation in mire, the paper dissertated detailedly the role of zonal climate on peatland formation and distribution, and suggested that the formation and distribution rule of peatlands are not controlled by zonal climate condition.The peatland distribution does not follow the zonal variation law.Having analyzed the role and status of several contradictions connected with the formation and distribution of peatlands, which included the oppositions of zonal climate and mire microclimate, the status quo of peat distribution and peat natural distribution, the regions of no peat distribution and the regions where peat can not form, and region difference and the zonal variation law, the conclusion suggested that the explanation for the formation and distribution rule supported by "the theory on climate cause of peat forming" is illogic.Mire microclimate can form in different climate zones, and they all have the characteristics of wetness.The formation and distribution of peatlands are mainly related with microclimate and anaerobic condition resulting from inundation.Because of the redistribution of surface water inundation is not controlled by precipitation, and some regions where precipitation is little can also be inundated, which resulted in the formation of peatlands.Zonal air temperature and precipitation may affect the area of peatlands in different zones, but under the zonal climate condition, zonal natural complex should be developed, which illuminated that the zonal climate condition is not the cause of peat formation.It is illogical to analyze the rule of peat formation and distribution based on the index of zonal climate.Because of anthropogenic affection on the progress of peat formation and distribution, the natural distribution pattern of peatlands has been changed greatly, and the status quo of peat distribution is not the reflection of natural rule.If some conclusions on the formation and distribution rule of peatlands were coincided with the status quo of peatland distribution, it must not be the reflection of the natural distribution rule of peatlands.It is obviously that a correct conclusion can not be drawn to analyze the natural distribution rule of peatland based on the status quo of peat distribution.Zonal climate condition is not the causes why peat can not form somewhere.The facts that peat can be found in all natural zones, whose characteristics are similar, and it is unnecessary to make a difference among them, illuminated that peatlands are a kind of azonal complex.Although zonal air temperature and precipitation may play an important role on the area of peatland in different natural zone, zonal variation law is not a kind of statistic law rather a law on spatial change and "have and haven't" of natural complex.There are some differences among the peatlands in different regions, but the comparability among peatlands is their main characteristics.The differences and comparabilities of peatlands among difference regions both need to be taken into account.As a kind of azonal complex, the distribution rule of peatlands does not follow zonal variation law.
  • Paleoclimatic Change Recorded by δ13C of Peat Stratum on North-bank of Changjiang River in Nanjing since Last Stage of Late Pleistocene Epoch
    ZHENG Chao-Gui, ZHU Cheng, GAO Hua-Zhong, SHEN Hong-Yuan, MA Chun-Mei
    2006, 26(3): 328-334. https://doi.org/10.13249/j.cnki.sgs.2006.03.328
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    Based on the analysis on the characteristics of the organic carbon isotope of the peat stratum in Linfengqiao profile on the north bank of the Changjiang(Yangtze) River in Nanjing since the last stage of the Late Pleistocene, it is shown that the δ13C values of both in the upper and lower peat stratum in Linfengqiao profile are lower than -23.79‰, and their organic matter is from C3 plants.The δ13C values of the upper peat stratum are higher than that of the lower.The result of 14C dating indicates that the upper peat stratum was mainly formed in the Holocene Megathermal and the lower peat stratum was mainly formed in the period of Younger Dryas.So it can be seen that the formation of peat does not absolutely lie on the climate changes.Combined with other research conclusions, it is confirmed that Holocene Megathermal Maximum was about between 8.2 cal.ka B.P.and 7.0 cal.ka B.P.in this area, before and after this period, the temperature had been down for a shorter time.During 12.8-12.1 cal.ka B.P., the temperature fluctuated frequently in this area.The temperature was lower in the two periods of 12.8-12.7 cal.ka B.P.and 12.6-12.2 cal.ka B.P., and they could contrast with the events of Older Dryas and Younger Dryas respectively.The temperature during 12.7-12.6 cal.ka B.P.was higher and it could contrast with the event of Allerod.In the period of 12.2-12.1 cal.ka B.P., it shows that after the event of Younger Dryas, the climate became warmer rapidly, so it could be regarded as the beginning of the Holocene.
  • Evolution of Jiuduansha Wetland in the Changjiang River Estuary During the Last 50 Years
    YANG Shi-Lun, DU Jing-Long, GAO Ang, LI Peng, LI Ming, ZHAO Hua-Yun
    2006, 26(3): 335-339. https://doi.org/10.13249/j.cnki.sgs.2006.03.335
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    Based on the topographic maps dated from 1958 to 2004, supported by the GIS software ArcGis8.2, the paper mainly deals with the evolution of the Jiuduansha tidal island.The result shows that there have been tow basic types of change during the long course of natural siltation and erosion: continuous change and periodic change.The former includes broadness of the island area, down stream migration of the head of tidal island and continuous siltation of the tail of tidal island.The latter includes the tidal island swaying south.On the other hand, the deep-water channel project at north passage of the Changjiang River changed the natural sultation pattern of Jiuduansha tidal island.A very large area from the head of Jiuduansha to Jiangyanan tidal island was silted greatly.The speed of accumulation declined and the shape of Jiuduansha tidal island leveled off after the project.
  • Cultivation Effects on Soil Organic Carbon Dynamics in Sanjiang Plain, Northeast China
    ZHANG Jin-Bo, SONG Chang-Chun, YANG Wen-Yan
    2006, 26(3): 340-344. https://doi.org/10.13249/j.cnki.sgs.2006.03.340
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    We selected adjacent Deyeuxia angustifolia meadow and farmland cultivated 1,3,5,9,15,25 and 35 years, to study cultivation effects on soil biological properties and organic matter dynamics in the Sanjiang Plain in Northeast China.The results showed that cultivation resulted in decrease in the microbial biomass carbon (MBC), microbial quotient(MQ), and basal respiration (BR).While, metabolized quotient (qCO2), potential respiration/basal respiration(PR/BR), and PR/MBC ratios obviously increased with cultivation.Converting wetland soil into agriculture soil resulted in significant decline in carbon availability and efficiency of microbial populations in conserving C.There are clear relationships between soil microbial properties.The method evaluating more parameters simultaneously can provide complete and true information about the soil microorganisms and carbon dynamics.
  • Impact of Global Warming on Latitudinal Temperature Gradients in China
    LU Ai-Gang, PANG De-Qian, HE Yuan-Qing, PANG Hong-Xi, YUAN Ling-Ling
    2006, 26(3): 345-350. https://doi.org/10.13249/j.cnki.sgs.2006.03.345
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    Global warming or any climate change may cause changes in other geographical elements, including changes in sea level, amount and pattern of precipitation, climate patterns and various other forms of climate change.Such changes can trigger various detrimental effects by causing flood, drought, heat wave, reduction of agricultural yield or in extreme circumstances, and cause mass extinction.The temperature variation in China is so complicated that even the temperature trends are completely different in the same period, with temperature increase trend in some areas but with temperature decrease trend in some other areas.So it is very significant to discover the global warming impacts in China and find the regional response laws to global warming.In this paper, the data set of 160 National Meteorological Observatory stations with long-term monthly temperature data for China has been analyzed to discover the warming pattern in China, i.e.finding the variation of temperature gradients in the past half century.By calculation and analysis, it is found that, with the global warming in the past half-century, the latitudinal temperature gradient became smaller and smaller, with a bigger magnitude in winter than in summer and a larger quantum in higher latitude than in lower latitude.The variation of the latitudinal temperature gradients in China is due to the different continentalities of the areas with different latitudes.And the stronger the continentality, the larger amplitude the temperature change will be.Also, it is found that the temperature changes of different seasons are asynchronous.Although human activities are contributing more and more to climate change, landforms and latitude effects seemed to be dominating factors influencing the spatial distribution of climate change of China in the 20th century.
  • Strategic Environmental Assessment for Construction of International Ship Center Based on System Dynamics in Dalian
    XU Ling, CHEN Chong, SHANG Jin-Cheng
    2006, 26(3): 351-357. https://doi.org/10.13249/j.cnki.sgs.2006.03.351
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    The construction of international ship center is a complicated and comprehensive engineering system, and relation in the system are reticular.The system dynamic method is applied to simulating the system.Considering the faults of technique of Strategic Environmental Assessment, a method, System Dynamics, is introduced into Strategic Environmental Assessment for the construction of international ship center.Based on analyzing impact factors and effect of system of international ship center, model on system dynamics is established including population, economy, transport, energy and environment subsystem, and the model is simulated and tested with some statistic data in Dalian.It is concluded that emulational results is in accord with practice.Therefore, system dynamics is well applied in the SEA, and can provide basis on plan with scientific decision.
  • Loss Evaluation of Urban Debris Flow Hazard Using High Spatial Resolution Satellite Imagery
    TANG Chuan, ZHANG Jun, WAN Shi-Yun, ZHOU Chun-Hua
    2006, 26(3): 358-363. https://doi.org/10.13249/j.cnki.sgs.2006.03.358
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    This paper approached an integrated methodology for urban debris flow loss estimation.Procedure of the methodology involved debris flow hazard zonation, image interpretation of urban land cover, model establishment for loss estimation, and property value calculation.Debris flow hazard zonation on the alluvial fan of the study area are created by overlaying distributed flow depth and velocity maps, which are produced through the numerical simulation.The possible loss estimation model is formulated based on stage-damage relationships between different debris flow hazard level and land-use features.Nowadays, earth observation techniques can contribute toward more accurate urban debris flow hazard modelling and they can be used to assess damage to residential properties, infrastructure and agricultural crops.For this study, detailed land cover information was derived by using the Quickbird high spatial resolution satellite imagery.Based on detail interpretation for the Quickbird image, the land cover of the study city was classified into 5 first level types, 10 second level types and 16 third level types.We calculated and evaluated the economic loss to different land-use features based on a GIS statistical tool.
  • Analysis on Synoptic Type and Feature of Physical Parameter Field of Great Weather Process with Ice-snow and Cool Disaster
    WANG Xiu-Qing, YANG Xue-Yan, Chen Chang-Sheng, WU Xian-Jun
    2006, 26(3): 364-368. https://doi.org/10.13249/j.cnki.sgs.2006.03.364
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    By the analysis on the daily precipitation and temperature of Changchun station during October to next march from 1971 to 2000,and respondedly NCEP/NCAR reanalysis data, the standard of the great weather process with ice-snow and cool disaster is proposed.Based on studying the upper and lower air circulation of 36 weather processes, four synoptic models are given.In addition, the physical parameter fields and normal parameter fields of those processes are researched.
  • A Review on Remote Sensing Technique for Salt-Affected Soils
    WENG Yon-Ling, GONG Peng
    2006, 26(3): 369-375. https://doi.org/10.13249/j.cnki.sgs.2006.03.369
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    Soil salinity is one of the major problems that affect crop growth and yield,and often lead to degradation of cultivated land.Recent advance in mapping and monitoring salt-affected soils by means of remote sensing has shown that this technology holds great promise in generating accurate results at enhanced speed and reduced cost.This paper first summarizes the role of ground data in detecting salt-affected soils,such as electrical conductivity of soils,underground water table,degree of mineralization,field-derived spectra of saline soils,and vegetation.In situ collected and laboratory data are very important in mapping and detecting salinity based on remote sensing technique.This paper then discusses the spectral properties of salt-affected soils,visual interpretation of saline features from remote sensing images,and use of vegetation as an indirect indicator.Key issues in and approaches of identification and mapping of salt-affected areas based on remote sensing technique are reviewed next.This review reveals that a multiplicity of remotely sensed data has been employed widely to investigate,identify,and monitor the surface salinity status of soils and its spatial distribution.The obtained results have demonstrated the value of spectral reflectance data for the calibration of remotely sensed data,ascertained the optimal bands in detecting salt-affected soils using spectra unmixing,established training range selection and mapping methods based on hyperspectral data for the validation of the quantitative information extracted from satellite data.These studies have used digital image interpretation,image transformation,hyperspectroscopy techniques in combination with GIS in order to map the distribution of salt-affected soils.Some studies have shown that hyperspectral remote sensing data have been applied to study soil salinity at an increasing pace.This technology carries great promise in producing more detailed and accurate soil salt information.
  • Overview on Studies of Medieval Warm Period in China
    GAO Jian-Hui, LIU Jian, WANG Su-Min
    2006, 26(3): 376-383. https://doi.org/10.13249/j.cnki.sgs.2006.03.376
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    The Medieval Warm Period (MWP) is one of the most important climate events happened in the last two millennia.The research work has been carried out mainly by using various proxy records to reconstruct climate.Now the high-resolution proxy records that can reveal environment change are ice core,tree-ring,historical documents,lake sediment and stalagmite,etc.With the development of proxy data, many achievements have been obtained on the MWP climate reconstruction.However, some questions, such as whether the MWP is a global phenomenon, what are the temperature anomalies and the climatic characteristics in the MWP, what are the causes of the MWP, and so on, still have some arguments because of the regional restriction of the reconstructed datasets, different sensitivities of proxies to climate change and different climatic and environmental significances.Moreover, there are errors in dating of reconstruction.In China, based on the results of analyzing reconstruction data, we find the opinions of researchers on "is there MWP in china?"are not consistent.And on the question of the changes of temperature in the MWP, we find the proxy records in the eastern China mainly are historical documents,while the proxy records in the western China mainly are ice core, tree-ring,etc., because of the absence of records on historical climate records in the western China.Most researchers agree that there are distinct differences of temperature change between the eastern and western China.The most importance is that there was a distinct warm period in the eastern China during 900-1300AD, and the warm record in the western China was not obvious in same episode.For the future, in order to fully understand the characteristic of the MWP climate from viewpoint of dynamics, we should strengthen the research on accumulation and ration of high-resolution proxy records, integration of various proxy records and reconstruction sequences, and comparison study between paleoclimate simulation and reconstructed results.