The construction of national resources and environment database and information sharing platform include building of natural features, population, attribute database of environment sustainable development and spatial entities; spatial integration of global database; model researching and model base building; resources and environment metadata management; data compressing; data safety; software researching; and development and internet workstation building of national resources and environment database. This research will develop a network performing system of high efficiency and safety data integration and spatial information sharing and knowledge transmit. It will provide for policies and law departments and research institutions a spatial-temporal data platform in resources and environment domain. It will also play an important and strong role in supporting national economy and earth science researches.
This paper introduces the fundamental concept, conceptual schema, and the method of resources and environment information classification and coding, and describes the data layer organization, conceptual database, and the logical database of national resources and environment scientific database initiative. It then explores the application schema of resources and environment scientific database by optimization and integration of several thematic resources and environment and geographic information classification and coding scenario. The paper also illustrates the GIS-oriented geographic information classification and coding offers an important solution to the geospatial data coverage arrangement and structure construction of attribute data file in conceptual level, also an important approach for data sharing and semantic interoperability between different applications. Finally, the paper concludes by presenting some aspects of resources and environment information classification and coding, and also suggests the further work on this domain.
The authors analyzed, at first, the background of the National Physical Atlas Database (NPAD) and its information products, and concluded that NPAD represents China's scientific level, and plus its information products, they showed the integration of the atlas' scientific value and social value. Secondly, the paper analyzed the project's scientific intension, concluded that it represents the transferring from Digital Cartographic Model (DCM) to Digital Landscape Model (DLM), as well as the integration of DCM and DLM. Thirdly, the technical feature of the project was related, i.e., we not only placed emphasis on database development, but also paid attention to information sharing technologies in our project. Fourthly, the paper summarized the total characteristics of the project, that is, the combination of dynamic, multiple scale browsing of spatial-temporal feature and static deep analysis & process, of geo-information. Finally, the authors predicted the prospect of China's National Atlas Series, i.e., to develop and construct National Atlas Information System.
The paper examines how to establish metadata standard and metadata management system of National Resource and Environment Spatial Database. It also discusses some issues concerning the construction of metadata database of National Resource and Environment Database. In the construction, low quality of metadata results in depression of metadata's function and acquirability of the datum. Additionally, this paper gives a new direction of metadata-base research. According to multi-layer metadata model, it combines extensible metadata model with inhomogeneous metadata to improve metadata quality. This paper also puts forward a method that can make metadata-based service convert from passive mode to initiative mode.
The metadata standard of data in resources and environment information system (REIS) has been created. As for the model and method metadata, which is very important to the usage of data, it has not been described in detail. So we put forward the idea and the concept of the model and method metadata, also advance a service model for the model and method metadata in order to realize efficient management and distribution for service of the model and method. Finally we draw a conclusion that it is feasible to realize the GIS service based on the model and method metadata.
This paper addresses two kinds of objects in geographical systems in which geo-process events occur. They are base objects and event objects respectively. Base objects, as fundamental framework and conditions for some events happening, are ones that exit in geographical environments, and will not change entirely within an observational period. Event objects are ones that do not exist until some events take place. Event objects change dynamically with space and time, and have a limited life span. Unlike base objects, research on event objects are less highlighted by traditional geographical information systems, especially on aspects of data model of spatial pattern and dynamic 3-D graphical representation. The conceptual framework of base objects and event objects are beneficial to designing data model in simulation and visualization systems. However, base objects and event objects are put forward just from a perspective of complete representation of geographical systems, other than of human-computer relationship. With regard to rapid 3-D graphic rendering, proper visual effects, and human-computer interaction in real time, scene data model should be considered essentially besides data models of base objects and event objects. Including object data base and scene data base, a system framework of computation visualization environment is then presented. The visualization environment system allows users to justify model and visualization parameters, to implement model computation and visualization by means of process steering. As a case, flood simulation is employed to establish a computation visualization environment prototype system, GeoVision, developed with Visual C++ and OpenGL. A preliminary experiment is conducted via flood model computation and 4-D visualization in the the Gaohu flood diversion area in the Puyang River, Zhejiang Province, China.
In order to find the best way of distributing spatial data on internet, we distribute the thematic data of Heihe drainage area based on three different WebGIS tools, i.e., DIAL, IMS and Jshape. Compared to these three methods, we conclude that MapObject IMS is a good method to distribute vector map such as ESRI's ArcView shape file and ArcInfo Coverage file. But since there are a lot of remote sensing image data and digital elevation model (DEM) data in these areas, MapObject IMS does not have the capability of distributing grid data. Jshape is only convenient to distribute simple and small vector map. However, DIAL is a very useful tool for distributing grid data. Because of DIAL's effectiveness and compatibility with the well-organized data format HDF, we think that it is the suitable choice to publish the earth scientific dataset by using DIAL on the Internet.
As discussed by many researchers, geo-spatial data have scale characteristics on spatial, temporal and attribute field, and geo-spatial data at different scales were chosen for various applications to meet different needs in each application case. So the concept of appropriate scale of geo-spatial data was raised, that is to say, there should be one or more appropriate scales of data for special data application. Unfortunately, no precise formula of appropriate scale chosen for applications has been set up by geographical researchers up to now, and the appropriate scale was chosen by users based on their experiences. Based on those cases, the paper lists the judgment index for appropriate scale selection, and gives one formula of appropriate scale for the application of land management of Shandong Province, eastern China. In the study area, different scales of 1:100,000, 1:250,000, and 1:1,000,000 landuse datasets were chosen for the appropriate scale analysis. The total area of each kind of landuse type for all the three scale datasets is calculated and compared with total area number by field investigation, and the landuse patterns are also created by calculating distance between each land parcel geometrical center. The author finds out that 1:100,000 scale landuse dataset is more appropriate for landuse analysis and management for a region like Shandong Province with a total area of less then 160,000 km2.
Based on describing the concept, content, types, structure and characteristics of geo-information products, and taking some information products in the database project of the Chinese Academy of Sciences as examples, the authors firstly discussed some theoretic problems, i.e., the value orientation, depth of information process and information propagation potential, best model of geo-information storage and display, as well as the author right, making right and copyright of geo-information products. After that, some technological problems for the development of geo-information products are discussed, including data collection, extraction, derivation and multiple representation of geo-information, and the technologies of geo-information product making, as well as geo-information sharing, communication and application technologies.
This paper discusses particularly the method and process of pixelizing the statistical population data. Firstly, the regionalization of spatial population distribution is finished. Secondly, the models of spatial population distribution based on the data of land use and land cover deriving from Landsat TM is established to calculate the population coefficient dwelling on different types of land use. Thirdly, the 1-km gridded population data supported by GIS is calculated. Then the results were modified according to DEM and inhabitant place map. Of course the sub-area data sampling randomly from the first class regions tests the precision of the results.
This paper designs a model to calculate an index of population distribution for each county and province. The index is related to the density of population, natural condition, the level of economic development and the density of traffic lines. A population barycenter of a province is defined according to which county index is closest to the provincical one. Then a 3D space of population distribution is established using the index (z) and the coordinates (x, y) of the barycenter. The distance in 3D space is calculated between any two provinces. According to the principle of minimum distance, China is classified into eight regions of population distribution.
An overview of the development process of soil information system in China and abroad, which was the basis of "digtal soils", was conducted systematically, and particularly the establishing basis and the design of spatial database for China's 1:1,000,000 soil database were introduced in detail. According to the regulation of the research group, the codes for soil order, great group and subgroup were designed and were also listed in this article. Then the creation method, main content and corresponding parameters of the soil attribute database were all expounded. Furthermore some preliminary suggestions to the national soil database were also put forward.
In order to realize the target sharing of lake information resources, Browser/Server framework was adopted, ArcIMS acted as publisher of maps on internet, advanced ASP technique combined, and lake database on internet developed. Lake information resources include physical, chemical and biological characteristics of lakes, as well as maps, remote sensing images, scenery pictures, etc. There are basic management and spatial analysis functions to lake database in the lake information system based on WebGIS. They are mainly: editing and updating spatial and none-spatial data, searching and inquiring information, displaying, zooming in, zooming out, and roaming of vector data, buffer analyzing and thematic mapping, and so on.
Based on remote sensing data, the regional landscape dynamic patterns of wetland are firstly analyzed with the help of the quantitative analyzing models in landscape ecology in the Sanjiang Plain during the past decades. At the same time, in order to realize the situation of wetland shift into other types of land use, we take Fujin county as an example to make further analysis of land use. Results show that the wetland in the Sanjiang Plain has greatly reduced in the past decades with the decreasing rate up to 51.33% from 1980 to 1996 and 4.19% from 1996 to 2000. This shows that the reducing rate has become less and less. The fragmentation of wetland was serious from 1986 to 1996 and less serious from 1996 to 2000. This indicates that the wetland reclamation in the Sanjiang Plain has turned into wetland inning instead of wetland fragmentation. Paddy field and dry land are the basic land use types converted from wetland reclamation. The center of mass of wetland distribution has been moving from the northeast to the southwest. The wetland mass reclamation in the Sanjiang Plain resulted in regional climate change. The cold and humid climate in the Sanjiang Plain has become warm and dry. This makes the wetland in the northern part where the climate is cold and the wetland in the eastern part where the water is log become easier to be reclaimed. The paper also puts forward suggestions to protect and rehabilitate the wetland in the Sanjiang Plain.
The establishment of the Chinese Glacier Inventory Database metadata standard references the Federal Geographic Data Committee's (FGDC) Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998). The metadata format requirement of EOS-HDF is also taken into account. The metadata standard include fifty fields which storage the data identification information, data quality information, spatial data organization information, spatial reference information, distribution information, and metadata reference information. Two data storage fields are added to record the data storage information, which can realize the management of data resource by using metadata. There are two metadata application cases, one is data resource query page based on the metadata and the other is data warehouse management model based on the metadata.
Sand-dust storms occurred frequently in Northwest China in recent years. In order to forecast and prevent sand-dust storm occurrence, it is important to analyze the extent, magnitude and spatial distribution of sand-dust material source area. Aeolian erosion takes place on the bare surface of loosen material in arid and semi-arid regions, including cultivated land, low coverage grassland, sandy land, gravel Gobi, salinized land, and nude clay land. By using digital method of remote sensing and geographical information system techniques, TM images of the year 2000 have been interpreted to establish the database of sand-dust material source area in Northwest China. Based on studies and analysis of these databases, the following conclusions can be obtained: (1) In 2000, sand-dust material source area covers 138,612,007 ha in winter and spring, and 130,427,035 ha in summer and autumn. (2) In sand-dust storm source area, only 34.71% of land is used or usable, and the grassland occupies a large part of it. (3) In sand-dust storm source area, the strong aeolian land is almost equal to the weak aeolian land, and the extent related to dust is greater than that to sand. (4) The countermeasures are mainly to encourage farmers to spread straw on the land after harvesting until next planting season. The straw can protect the cultivated land effectively from aeolian erosion and keep the winter snow from freezing on these farmlands. (5) With the decreasing of water resources, cultivation practice in sand-dust material source area should be restrained to prevent the land from being aeolian eroded.
Desertification is one of the most serious problems in China and in the world, and has seriously affected socioeconomic aspects and geographical environment. Based on remote sensing and geographic information system, we conducted extensive investigations on the desertified land, including desert, sandy land, Gobi, and saline-alkali land, in northern China and set up database of the desertified land. According to the database, about 41.2 % of the six provinces in northern China was covered by desertified land. The distribution of desertified land is regular, from east to west, desert area, Gobi, and saline-alkali land increased and sandy desert decreased. According to the analysis of the climate background, we found that low precipitation and strong wind constitute the common characteristics of the desertified land area, and most of the desertified land is located in the arid and extremely arid areas where the middle or low wind fields exert great influence on the desertified land. Affected by the special distribution of precipitation, from east to west, the area of the fixed and semi-fixed sandy land decreased whereas the shifting or semi-shifting sandy land increased gradually. Most Gobi and saline-alkali land is concentrated in Northwest China.
According to a series of landscape indexes the sandy desert and sandy land were classified into four types as shifting, semi-shiftng, semi-fixed, and fixed. Through interpreting TM images in 2000, the database of sandy desert and sandy land of China was established at a scale of 1:100,000 by remote sensing and geographical system techniques. And based on analyzing the database, the following points can be concluded. (1) There were 38,734,730 ha of gravel Gobi and 124,230,119 ha of sandy sesert and sandy land in China in 2000. (2) The shifting type occupied 41.46% of the total sandy desert and sandy land in China, the semi-shifting 24.21%, the semi-fixed 20.38%, and fixed only 13.94%. (3) Sandy desert and sandy land were distributed in different bioclimatic zones of 719 counties or cities in 28 provinces or autonomous regions, where 62.33% were distributed in extremely arid zone with shifting and semi-shifting types in domination; 21.94% distrbuted in arid zone with fixed and semi-fixed types exceeding the sum of shifting and semi-shifting types; 8.78% of them distributed in semi-arid zone having fixed and semi-fixed also as main types; 6.78% distributed in semi-humid zone with greatest part being fixed and semi-fixed types; and 0.15% of them distributed in humid zone, having fixed and semi-fixed as the main types with shifting type exceeding semi-shifting and semi-fixed types.
