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    15 January 2000, Volume 55 Issue 1 Previous Issue    Next Issue
    Digital Earth and Earth Observation
    CHEN Shu peng, GUO Hua dong
    2000, 55 (1):  9-14.  doi: 10.11821/xb200001001
    Abstract ( )   PDF (224KB) ( )   Save
    Digital Earth is a global strategic idea. It is centered on the use of digital data acquisition, storage, transmission and processing technology to control and operate the global affairs. Digital Earth is an information Earth for processing the natural and social economic issues by means of digital technology; it is a virtual Earth capable of mosaicing voluminous data, displaying multiple resolution and 3-D data. Earth Observation is a basis for constructing the Digital Earth. The information on Earth observation is one of the core information sources. “Digital Earth” has involved many new theories and techniques: acquiring raw digital data for the Earth, data standard, interactive operating techniques, voluminous data storage and compression, distributive object technique, spatial data warehouse, virtual phenomena, knowledge & distributed intelligence, graphic search engine, WebGIS and various kinds of application models. Only earth observation technology from the space can provide global, repeated and continuous data covering the earth surface. China has launched a series of returnable satellites and 3 meteorological satellites. On October 14, 1999, Resources-1 satellite was successfully launched. This is an Earth Resources Satellite called CBERS, developed jointly by China and Brazil. Recently, China has paid special attentions to Ocean-color small satellite. A proposal for 3-dimensional mapping of an Earth observing small satellite has been approved. In the last 10 years, we have developed several sets of airborne remote sensing systems, which include high altitude airborne remote sensing operational system and disaster monitoring system. The Remote Sensing Satellite Ground Receiving Station of China was built in 1986. At present, the station can receive 7 kinds of data. The essential task for the strategy of “Digital Earth” is to provide true and reliable data completely and promptly. It is not easy to implement this task. Therefore, the governments, enterprise and companies of all countries are needed to devote their efforts to support the construction of “Digital Earth”, to enable data sharing, and to make convenience for using computer network and exploring the information resources. At present, the demands of category index system and spatial resolution for a study on a global scale is roughly equivalent to the categories at a scale of 1∶200000 to 1∶500000. These data meet the demands of most academic activities such as CEOS, IGBP and Global Mapping programs since the Second World War.
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    A GIS-based Approach to Flood Risk Zonation
    ZHOU Cheng hu, WAN Qing, HUANG Shi feng, CHEN De qing
    2000, 55 (1):  15-24.  doi: 10.11821/xb200001002
    Abstract ( )   PDF (545KB) ( )   Save
    Flood risk can, in general terms, be defined as probability time consequence. It consists of flood hazard analysis, vulnerability analysis and damage evaluation. A variety of methods have been developed and applied. Among them, Quantitative Risk Analysis (QRA) is a method of quantifying risk through systematic examination of the factors contributing to the flood hazard and affecting the severity of flood consequence, their interaction and relative contribution to the occurrence of the flood. The QRA technique is well established in many fields such as chemical engineering and hazardous materials processing. The application of QRA to flood risk is relatively new and still under development. While the basic risk assessment concepts and tools can be used, the methodologies need to be adapted. Category-based model for flood risk analysis is used to assign a value to each driven-factor such as triggering factor of rainfall, dam break, ground surface conditions of topography, land cover, and others. The keys to the model are to synthesis the spatial-referenced data and create the risk zone. The diffusion of Geographical Information Systems (GIS) technology opens up a range of new possibilities for hazard mitigation and disaster management. Microzonation is greatly facilitated by the kind of automation that GIS offers, especially as it involves comparison, indices and overlays in much the same way that GIS does. In this article, ArcInfo GIS has been chosen to quantitatively represent the influencing factors, spatialize the data into the uniform grid system, and transfer all the data item into the effect degrees on the probability of flooding. At last, with the support of Arc/Info GRID model, a categorical model for flood risk zonation has been put forward. The approach has been applied to the Liaohe river basin, the north-eastern of China, flood disaster risk zonation. The results show that the flood risk of the lower reaches of the Liaohe river is more serious than other places, which accord with the fact. The case study showes that the GIS-based category model is effective in flood risk zonation.
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    Operational Remote Sensing Methods for Agricultural Statistics
    WU Bing fang
    2000, 55 (1):  25-35.  doi: 10.11821/xb200001003
    Abstract ( )   PDF (472KB) ( )   Save
    Crop production statistics are of vital importance to a country such as China where the agricultural production is highly susceptible to the vagaries of monsoon and the 75% population is farming activities related. The NOAA AVHRR data are used to monitor the crop growth over the entire country at decade period during growing season from March to October. The acreage under crops are estimated through estimating crop proportions to farming land from remotely sensed data, including TM and Radarsat data, with support from intensive ground surveys. The ground surveys are served both as a ground truth for classification of remotely sensed data and as reference data of accuracy testing. The agrometeorological models are used for yield estimation on every homogenous yield level zone.
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    Distribution and Seasonal Change of Net Primary Productivity in China from April, 1992 to March, 1993
    SUN Rui, Zhu Qi jiang
    2000, 55 (1):  36-45.  doi: 10.11821/xb200001004
    Abstract ( )   PDF (499KB) ( )   Save
    It is significant to estimate terrestrial net primary productivity (NPP) accurately not only for global change research, but also for natural resources management to achieve sustainable development. The estimation of NPP by climate data is only a potential NPP rather than true NPP. But remote sensing data can describe large scale distribution of plant resources better. So, 1 km AVHRR NDVI data was used adopted here to estimate the distribution of NPP in China. First, the fraction of absorbed photosynthetically active radiation (FPAR) by vegetation is derived from NDVI data using the linear relationship between FPAR and vegetation index. The incident PAR was estimated by climate data. Then NPP was calculated with absorbed PAR and energy efficiency ε * g . In order to estimate NPP more accurate, the effects of temperaturely, soil water content and plant respiration were also considered in the model. The model can be described as below:NPP=ε g×f 1(T)×f 2(β)×FPAR×PAR-Rin which f 1(T) and f 2(β) mean the temperature and soil water content effects on photosynthesis, R means plant respiration including maintenance respiration and growth respiration. Monthly and annual net primary productivity in China was computed by monthly 1km AVHRR NDVI data, climate data between April, 1992 and March, 1993, vegetation type map and soil texture map. The results gained were compared with ground-observation and Miami model results. It shows that the results using remote sensing data are closer to truth. Total annual NPP in China is 2 645×10 9tC. The distribution of NPP in China is mainly effected by precipitation and has the trend of decreasing from south east to north west. Finally, the seasonal change of NPP was investigated on the basis of monthly NPP.
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    Submerged Simulation of Flooding and Waterlogging in Taihu Watershed
    WANG La chun, XIE Sun ping, ZHOU Yin kang, DU Jin kang, PAN Hua liang
    2000, 55 (1):  46-54.  doi: 10.11821/xb200001005
    Abstract ( )   PDF (322KB) ( )   Save
    Plain with river network regions are generally located in great river delta, in which they are usually the most developed in China. However, the economic loss could be much severe if they are suffered flood and waterlogging disaster. According to numerical model of river network unstable flow, the present paper analyses the flood generating process in Taihu Basin. Furthermore, the submerged area of flood and waterlogging in the Basin is simulated with geography information system (GIS). It has reasons to believe that it is useful to provide scientific basis for mastering the flood and waterlogging disaster and making decision on flood prevention and flood disaster reduction. There is a great variety of landscape exists in Taihu Basin, including mountains, plains, lowlying dykes, rivers and lakes. However, the runoff formation mechanics is different for different topographical conditions. Furthermore, the space time distribution of precipitation in the Basin is non uniformed because of the large basin area. Therefore, 34 precipitation runoff polygons or units are divided according to hydrological data for years in Taihu Basin. Each polygon is further divided into three topographical types according to their topographical conditions, e.g. water surface, paddy field, and dry land. This paper calculates the discharge of each topographical type with different time interval based on the runoff formation mechanics of these three topographical types. Considering the discharges and their area percentage of different topographical type, the discharge of each precipitation runoff polygon with different time interval is figured. The Taihu Basin has complicated river network because of its rivers and lakes that spread all over the Basin. This paper puts the Basin two basic parts, that is, mountain part and plain part. In mountain part, 13 sub basins are conceptualized. Flow concentration is simulated according to instantaneous unit hydrograph method in these sub basins. At the same time, 419 rivers, 13 lakes and 267 nodes are conceptualized in plain part. A plain with river network model is constructed and flood movement in river network is simulated according to the numerical model of river network unstable flow. In practical simulation, except 13 mountain sub basins whose flow concentrates at a certain node, the discharge of plain and river network is symmetrically drained into river networks around according to the discharge of precipitation runoff polygons and their drainability. The discharge can not drain timely stops in lowlying dykes, which is regarded as submerged runoff. Based on the constructed hydrological model in Taihu Basin, this paper constructs the digital elevation model (DEM) of Taihu Basin based on GIS. Furthermore, it is overlapped with grid precipitation runoff polygons. According to the simulated waterlogging discharge in each river network polygon, the largest submerged area in Taihu Basin in 1991 is simulated (Fig.4). The simulation has higher precision comparing to the practical submerged area of the Basin.
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    Environment Recorder in the Glacier from Mount Xixiabangma
    KANG Shi chang, QIN Da he, YAO Tan dong, Cameron P Wake
    2000, 55 (1):  55-65.  doi: 10.11821/xb200001006
    Abstract ( )   PDF (372KB) ( )   Save
    The seasonal variations of δ18O values and concentrations of major ions (Ca2+, Mg2+, NH4+, SO42-, NO3-, Na+, Cl- and K +) recorded in the 14 m firn core, which was recovered from the Dasuopu Glacier, are analyzed to understand the characteristics of seasonal variations of atmospheric environment in the Mt.Xixiabangma. The analyses of the correlation and EOF show that δ18O values are evident positive correlation with Ca2+, Mg2+, NH4+, SO42-, and NO3- concentrations, but not relevant with Na+, Cl- and K+concentrations. The variation trends of ion concentration that mainly source is dust in the atmosphere are represented by EOF1. However, the variation trends of sea salt ion concentrations are indicated by EOF2. And EOF3 indicates that the secondary seasonal variations of NH4+ and NO3- are negative correlation with Ca2+ and Mg2+, which probably mean other sources besides dust. “High values in spring and low in summer” of δ18O in the Dasuopu Glacier indicate that the low δ18O values in precipitation in summer monsoon season are controlled by the “amount effect”. However, the high δ18O values in spring are mainly affected by increasing temperature. The seasonal variations of atmospheric dust species recorded in the Dasuopu Glacier are high in spring and low in late summer. High concentrations of dust species (Ca2+, Mg2+ and SO42- ) are due to the import of spring dust storms from the arid and semi-arid desert regions in Asia. The atmospheric environment is clear in late summer in Mt. Xixiabangma region. Seasonal variations of sea salt ions concentrations are not so evident.
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    Lacustrine Records of Human Activities in the Catchment of Erhai Lake, Yunnan Province
    ZHANG Zhen ke, WU Rui jin, ZHU Yu xin, PAN Hong xi, WU Yan hong, XIA Wei lan, LI Xu sheng (
    2000, 55 (1):  66-74.  doi: 10.11821/xb200001007
    Abstract ( )   PDF (409KB) ( )   Save
    Based on the results of lacustrine environmental proxies from Erhai Lake, Yunnan Province,the lake responses of human activities recorded by lacustrine sediment in the catchment have been discussed. The Erhai Core of 310 cm long was sampled in the center of Erhai Lake with the water depth of 4 6 m. The modern sedimentation rate by 137 Cs test is ≤0 25 mm/a, which is consistent with the average sedimentation rate of the upper 100 cm with radio carbon years of 4 473±40 a BP at the bottom. Because the surface soil are rich in magnetic materials. The environmental proxy of magnetic susceptibility was obviously influenced by the way of land use especially the occurrence of farming agriculture. So the sharp increase of magnetic susceptibility at 100 cm with ca 4 500 a BP means the intensification of human activities especially the occurrence of farming agriculture. The time of the ancient farming occurrence recorded by the lake sediment is older than the archaeological relics with the radio carbon years of ca 3 800 a BP in Baiyang Village near the catchment of Erhai Lake. The surface soil is rich with elements of Fe and Al in the catchment of Erhai Lake. So the changes of chemical elements contents (Fe, Al) had close relationship with surface water soil erosion which controlled by the human activities in the catchment. The huaman relics of Malong in the catchment of Erhai Lake with the age of 34003100aBP which corresponding with the sharp increase of element Fe and Al. The lower content of Fe, Al in the upper 15 cm may be affected by the aquatic vegetation which can absorb some chemical elements including Fe and Al. The variations of pigments indicated the process of lake eutrophication induced by human activities. The first and second peaks of pigments correspond with the time of Malong Relics and the first population summit of Yunnan Province. The obvious increase of pigments was occurred in 1100 AD with the large population migrated to Yunnan. The proxies of lacustrine magnetic susceptibility, chemical elements and pigments are the efficient parameters to demonstrate the human activities in the catchment, which has important significance in the research on archaeology.
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    The Distribution of Environmental Disasters of Xinjiang Line in New Eurasian Continental Bridge
    CHEN Ya ning, CHEN Li jun
    2000, 55 (1):  75-83.  doi: 10.11821/xb200001008
    Abstract ( )   PDF (267KB) ( )   Save
    Various disasters, such as flooding, strong wind, sandy disaster, roadbed disasters and so on, often occurring along Xinjiang Line of the New Eurasian Continental Bridge, have seriously been affecting on the railway transportation. Flooding disaster, mostly takes place during Spring and Summer because of rainstorm and thaw snow water and often lead to roadbed sinking, train speed-limiting, even transportation ceasing. The flood could be occurred at 15mm/10min or 25mm/1h of day critical precipitation in Shanshan Railway Section, and above 30mm/d of that in Urumqi Railway Section. Windy and sandy disaster, in form of turning over train, digressing and burying railway line, is a particular type of disaster owing to several famous windy areas such as “Yandun windy area”, “Baili windy area” and “Sanshili windy area” in Shanshan and Urumqi Railway Sections. It is observed that the passes between hills in which the windy speed can reach to 8~12 grade because of windy accretion, are the key locations where often take place windy disasters. It is also discovered that sandy disasters could be occurred only when the windy speed of rising sand reaches above 6 m/s. Roadbed disasters, derived from clammy loess roadbed and salty-alkaline roadbed, taking the form of side-slope sliding, roadbed sinking and silt turning up owing to the seasonal changes of water and heat conditions, generally lead to railway-track transforming, train speed limiting, even transportation ceasing. This type of disaster, mainly distributing in Shihezi and Kuitun Railway Sections, takes place in Spring when the temperature rapidly rises to 10~15℃ and precipitation comes forth or in winter when the thickness of snow deposit on shade slope reaches above 20 cm. From the view of spatial distribution of disasters, Liuyuan section, accounting for 23 25% of total, is the most; Shanshan section, accounting for about 21%, is the next; Shihezi and Kuitun sections, respectively accounting for only 13 97% and 6 99%, is the least because this line just run for 11 years. But then, comparing the frequency and the density of disasters, the average of disasters occurring in Liuyuan section is actually not more than that in Shihezi, even Kuitun section, and Urumqi section is the top area not only in the density, but also in intensity. From the view of temporal distribution of disasters, the intensity of disaster taking place in 1990’s is far stronger than that in the past years because the flooding disasters in this region tends to increase in the late 20th. a century. Most of disasters, about 57 57% of total, appear in July and June because the rain season comes up generally in these times. In addition, flooding disasters often come forth in June and July, and windy and sandy disasters mostly in April and roadbed disasters in Mar and April.
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    The impact of land use on spatial and temporal distribution of soil moisture on the Loess Plateau
    WANG Jun, FU Bo jie
    2000, 55 (1):  84-91.  doi: 10.11821/xb200001009
    Abstract ( )   PDF (320KB) ( )   Save
    Soil moisture is a key factor for hydrological processes, plant growth and vegetation rehabitation in semi arid environments. A better understanding of the characteristics of soil moisture differentiation in space and time is important for improving hydrological processes and land management in both runoff and erosion control. However, the knowledge about spatial and temporal variability of soil moisture for different land use types and structures is rare in the hilly area of Loess Plateau of China. In order to analyze the relationships between land uses and soil moisture in space and time, five representative land use structures and seven land use types were selected to monitor soil moisture in Da Nangou catchment (3 5 km\+2) in Loess Plateau from May to October, 1998. The five land use structure combinations from top to foot of the hillslope were: cropland - cropland - cropland, cropland - woodland - orchard, fallow land - grassland - cropland, fallow land - shrubland - intercropping land - woodland and fallow land - shrubland - cropland - orchard. Soil moisture measurements have been performed biweekly at about 26 locations. The measurements were carried out on regular plot by using portable Time Domain Reflectometry (TDR) at five depths: 5 cm, 15 cm, 25 cm, 40 cm and 70cm. Based on above data, the spacial and temporal distribution of soil moisture are analyzed in seven land use types. The results showed that the changes of soil water content presented 3 peaks and 3 valleys during growing season and that the lag influence on soil moisture was found in woodland and intercropping land. Soil moisture changes of profile can be clustered into three groups, they are increasing, decreasing and fluctuant. The effect of five land use structures on soil moisture along hillslope were analyzed, two better land use structures for runoff and erosion control, were put forward, they were fallow land - shrubland - intercropping land (terrace)-woodland and fallow land - shrubland - cropland (terrace) - orchard. At the same time, benching terrace for crop-fruit tree intercropping system and breeding for deep-root plants were proven to be effective approaches in soil and water conservation in hilly area of loess.
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    A Theoretic Framework for Spatial Analysis
    WANG Jin feng, LI Lian fa, GE Yong, SHI Pei zhong, GUAN Yuan xiu, BUO Yanchen, WANG Zhi yong, Haining Robert
    2000, 55 (1):  92-103.  doi: 10.11821/xb200001010
    Abstract ( )   PDF (497KB) ( )   Save
    Spatial analysis refers to a series of techniques for analysing, simulating, predicting and coordinating the spatial processes. It is necessary to propose a new theoretic framework to integrate coherently the existing wide range of spatial analysis techniques, including spatial statistic indices, spatial regression and adaptive modelling, spatial mechanism dynamic modelling, integrated spatial statistic and spatial mechanism modelling, and spatial complicated system modelling, combining with analytic, numerical and analytic+knownledge solution. The unique characteristics of spatial data in its form and relationship among them require special tackling techniques. Spatial-temporal-attribute process summarizes the sub processes of spatial and related sub processes (Fig.1). Spatial-temporal process: diseases diffusion; morphology change: river course change; GIS space: disaster distribution and ore deposit; spatial pattern: distribution of river network and disease; time series: water level curve; and classic statistics: dicing. Based on the different theoretic frameworks of spatial analysis, a new theoretic framework, covering the wider range of techniques, has been setup (Tab.2), which consists with (1) the reasons of spatial association, in raw data and in residual of model. (2) the representation of spatial association: spatial structure and spatial interaction. (3) spatial data modelling: (3a) spatial point distribution (point pattern, spatial sampling, location choice); (3b) spatial linear regression equation (with spatial correlation structure in general form, in governing equation, and in residual), kriging, and filter; (3c) spatial nonlinear equation: regression, adaptive, and others; (3d) stochastic equation: distribution, and error propagation. (4) spatial mechanism dynamic modelling: (4a) human society (behavior, traffic network, etc.); (4b) physical (GCM, hydraulic, heat transfer, etc.). (5) spatial complicated system modelling: neural network, fractal, CA, etc. (6) spatial mechanism with stochastic modelling; (7) spatial graphic analysis; (8) spatial optimalization. (9) algorithms for spatial models: (9a) consequences of OLS (with spatial correlation in governing equation, and in residuals); (9b) spatial algorithms. (10) testing of performance (residuals, and governing equations).
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    The Change from the Geographical Space to Geocyberspace ——Review on the Western Scholars on Regional Effects by Telecommunication
    Henry Bakis, LU Zi
    2000, 55 (1):  104-111.  doi: 10.11821/xb200001011
    Abstract ( )   PDF (130KB) ( )   Save
    The geographical environment of all economic actors (citizens, firms, local governments, state governments, etc.) is already——and will be in the near future strongly modified by ICTs revolution. With cyberspace, the non geospace territories built on information electronic networks and without time constraints, it is the central role time instead of distance. The world becomes accessible in “real time” and user communication is not direct with other users but rather is a communication through an interface, such as WWW servers. The notion of cyberspace refers to a society where the technical interface is ever present. So, the process is necessarily a time interfaced communication. Cyberspace, is a kind of space where a state of “effective discontinuity” characterizes the spatio temporal scales of increasingly convergent information, telecommunication, computer and image transmission technologies. Along with time, the notion of space is changing as well. It becomes unimportant for the users. In the web, it is the nature of the problem solving process that is important and not the place from where the needed information is obtained. Work is becoming increasingly dematerialized. It becomes possible to work at any time and any place. This chapter wishes to review these issues in the light of literature on telecommunications geography . The aim of this chapter is to synthesize the main results obtained from research conducted over the past fifteen years. In so doing, we will make a distinction between several classes of authors who wrote about the role of telecommunications in local and regional economic development. Three positions exist. For maximizers, a total territorial revolution is underway, based on the disappearance of the constraints of geographic distance. For minimalists, the territorial impact of telecommunications networks is limited, insufficient and unspecified. They argue that even if telecommunications networks are able to prevent certain areas from being at a disadvantage compared to others, they are totally inadequate alone to promote development. For moderate, the territorial impact of telecommunications networks is potentially significant and even radical, but depends on other factors and often appears paradoxical since these networks favor centralization.
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    Characteristics and New Creations of “National Natural Atlas of China”
    LIAO Ke
    2000, 55 (1):  112-117.  doi: 10.11821/xb200001012
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    The “National Natural Atlas of China” (1999 edition) contains 540 maps in eight series of general, natural environment (geology and geophysics, geomorphology, climate, hydrology, soil, biology, and oceanography), natural resources, natural disasters and the utilizatioand protection of nature as well as 300 000 words of notes to the maps. The characteristics and new creations of the atlas as the following: 1. Basic scientific data and digits were extended and renewed on the time and space obviously, so it displayed scientific accumulations of geography and biology of China completely; 2. To implement the strategy of sustainable development, it concentrated reflected natural resources, natural disasters and the utilization and protection of natural resources in China, and stressed on the relationship between human and nature; 3. Deepened scientific specialization, many maps about animals and plants well reflected the biological diversity and deep research on it; 4. Fully reflected new advance and contribution of geographic scientific research of China, and expounded the forming and developing laws of natural environment; 5. There were more new creations and breakthroughs on designing and compiling methods and technologies, and realized thoroughly revolution from traditional technology to complete digitalization of computer design, compilation and automatic plate making.
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