| Based on the investigation of the social economy and natural environment of Yan'He watershed on loess plateau. With method of RS & GIS, the technology to pick up the regional eco-environment evaluated factors information and method of determining index system is studied in this research. The model for assessing the eco-environmental quality is built. Then discussed the effect of exploring land resources on the eco-environment. In addition, through analysis the remote sensing images in the different period, studied the primary characteristics of land use and vegetable covering and dynamic changes in last 10 years in this region. The study plays an important role in improving the eco-environment and promoting the sustainable development of society, economy, resources and environment in the region, which brings tremendous value both in theory and practice. The conclusions were as follows:i. Integrating analysis of remote sensing images, data and field investigations, including geometrical rectifying, amplifying, zoom, pan of images, then man-machine screen interpreting, the results are stored in computer, this method avoided error of the man-digitalization, enhanced the positional and qualitative accuracy. Analyzing the characteristics of image such as color, structure and texture, the symbol database is constructed that including digitalization and document format.ii It is inconvenience for using eco-environmental data due to its large and complexity. So database of eco-environment are constructed including spatial and attribute database in this paper. Spatial database main record and store land resources and position, shape, and its spatial relation of environment factors. Attribute database main record and store data about social economy and natural environment, which collected by referring and surveyiii The arable land area is 36.75 percent of total area, but high rate of reclamation and lower productivity is characterized by extensive cultivation and rough management. The forest area makes up 13.8% of total area, but little profit and low coverage rate. Grassland contributes 45.6% of total area, which is main natural wasteland. Residential land, water area, un-utilized land is 0.65%, 0.29% and 0.07% respectively. Arable land: forest land:orchard: grass land: water area is 1: 0.38: 0.08: 1.25: 0.02, which reflects the characteristics of land use which is mainly arable land and grassland. Form 1990 to 2000, the trend of land use in this region has transformed form arable land to residential land, vegetable plot, forestland and grassland, and uncropped land has transformed into forest-grassland.iv From analysis of anatomy of quantities and landscape figures in Yan'He watershed, the results show that the ways of land use is very complicated and area of every contribution is very different, that dry land makes up preponderance and distributes in various topographical features, but the waste land and natural grassland are small, the other types of land use are less small. In the first grade of land use in the interior of agriculture, types are more complicated than those of others. Types of vegetation covering of agricultural land are more diverse than those of others. According to the index of optical degree, we can know the area of divers method of crop is difference; the proportion of dry land is higher than that of others. The index of shape indicates that the quantities of each map-figure-spot distribute in normal school generally in the objective regions, which includes dry land, heard forest land, artificial forest land, natural grass land, uncropped land. It also shows that the simplest and the most complicated shape are less than others. The map spots of other use type are less and their shapes are more standard, hence their shapes are simple.v Applying the RS & GIS, describing the situations of eco-environment entirely and objectively, picking up the factors of assessment of eco-environment, bringing forward the principle of choosing the evaluated factors, building the reasonable index...
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