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| Poster Session 2 |
Land Use Mapping by Remote Sensing
II. Geographic Base Map Compilation
Any thematic map needs geographic base map as its carrier of thematic contents , so does a land use map. When transmitting one or several special thematic contents on to a base map, the elements of the base map are taken as the control and support of qualitative, quantitative and positional determination of the thematic contents, At the same time, there exist mutual conditional and mutual –controlled relationships between the base map elements and the thermatic contents. The distribution law and the occurrence and the development of the thematic contents are integrated into a specially organized geographic environment and hence the scientific level and the practical value of the thematic contents are improved.
The base map elements of a land use map are as following:
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water system. It included rivers, canals, irrigation ditches, lakes (ponds), reservoirs, oceans and marsh lands, wells and springs etc., They make up the fundamental structure of land use maps and are an important element of base maps. In addition, the water system is a basic type of land use. so index and capacity selection of the system should be made in greater detail and not only is its capacity demonstrated, but its structure and characteristics as well.
- Landform. Landform is a basic condition affecting the thematic contents of land use. The altitude and location of a terrain, its gradient and sloping direction and its material making up etc. directly influence and determine land use types and land use features. According to the practical land use map compilation requirements, the total or partial relief contour lines and elevation points should be selected. Land use maps can be compiled without showing their contour lines to avoid unnecessary confusion with the presentation of land use the metric contents.
- Residential area. Residential area is both the base map element and the thematic content of land use maps. The residential area selection can be made according either to the real map blotch size or to the consideration of both the administrative level and the block size involved. Also it can only select such index as administrative level and population of residential areas should be chosen depends on map compilation objective and map application purpose. In addition, some smaller residential areas which have special meanings and close relationship with land use thematic contents should be chosen.
- Transportation network. Here transportation network mainly refers to railways and highways. But when mapping lands are vast in area and sparse in population or maps are to be compiled on large scale, some lower level roads must be taken into account, such as tractor-plugging roads, cart roads, earth roads and pastureland paths etc.,
- boundary. What a boundary , provincial boundary, country boundary, commune boundary, drainage boundary, natural boundary and the boundary of economy are several kinds of boundary areas to be named here.
Once a map scale is determined, the same-scaled relief maps at their possible latest publications should be consulted to carry out the content element selection, delineation and drawing in an order of water system first, followed by topography, residential area, transportation network and boundary. At the same time, the newest rectified and processed remote sensing data should be used to make amending measurement and renewal of the content elements.
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