~ (137) Cs Soil Erosion And Soil Nutrient Loss Law Relationship And Its Three-dimensional Visualization

Soil erosion refers to the process of destroy, denudation, transport and sediment of soil, parent soil and the other referenced substance composition on the ground under the agent. It is the most serious ecoenvironment problem in the earth, which lead to the quick decrease of soil-quality and bio-quality and the destroy human being's living environment. ¹³⁷Cs tracing technique for soil erosion can provide the temporal and spatial variation information of soil transfer and sediment, with the character of high technology, precise, simple and rapid, and have becoming the maturity technic in the soil erosion field. Geographic Information Systems (GIS) is defined as an information system that is used to collect, store, manipulate, analyze, simulate and display geographically referenced data or geospatial data, and to provide various spatial and dynamic geo-information by using spatial geographic model analysis method, in order to support geographic research- and geographic decision making service. GIS is also be utilized extensively to soil erosion research. This thesis study the content of ¹³⁷Cs, variation and change trend of soil nutrient element in Miyun reservoir around by using the ¹³⁷Cs tracing technique; and display the part of soil erosion condition by using three dimensional GIS technique.Miyun reservoir is main waterhead of Beijing, of which the water quality is influenced by the soil erosion in Miyun around area directly. By means of field investigation and sampling, we chose 29 sampling areas on the ground of the different landscape ecology character, land use pattern and physiognomy morphological character, and take 104 sampling sites due to the various relief features. In the 27 non man-made destroyed sampling areas, we chose 93 sampling spot, while in the 3 human activity sampling areas, we chose 11 sampling spot. We analyzed the relation between 137Cs and soil organic, total phosphor and total nitrogen, then display the 3D effect of soil erosion modulus by using GIS technique, and implement the overlay of soil erosion modulus on the 3D terrain. The conclusion is shown as follows:1. By the estimation of soil erosion in Miyun reservoir surrounding, most of erosion modulus of sample area is from 500 and 2500 t ·km² · a^-1. The primary condition of soil erosion in this area can be regarded as slight erosion according to the national soil erosion grade. The erosion in the north area and the west area is more severe than the south area and the east area. Inthe man-made sampling area, human activity influence the soil erosion obviously, and the degree of soil erision is accelerated, the average soil erosion modulus is 8982.4t · km² · a^-1, even no ¹³⁷Cs is detected.2. Vegetation has a great influence on the soil erosion. Different vegetation specie and vegetation assemblage shows different effect on the resistance of soil erosion. The content of ¹³⁷Cs is highest in the Shrub, underbrush and arbor and is less, the combination of arbor and Shrub is least. That is to say, shrub is the best way to resist the soil erosion.3. Slope has a great influence on the soil erosion. On the gentle slope, the content of ¹³⁷Cs is higher. On the steep slope, the content of ¹³⁷Cs is lower. The slope is steeper , the loss of ¹³⁷Cs is more. On a slope, the content of ¹³⁷Cs decrease from the foot to the top, the variance of ¹³⁷Cs concentration in slope length per unit reduces while the slope length increase from slope top to slope foot.3. There exist a stable relationship between the soil organic matter conten tand ¹³⁷Cs content and a stable relationship between total phosphor and ¹³⁷Cs contentn in sail soil. In the whole research area, the correlation coefficient of ¹³⁷Cs and oil organic matter is 0.501. The correlation between total phosphor and ¹³⁷Cs is 0.502. In sampling area (Nanshishengnan) the correlation coefficient of ¹³⁷Cs and oil organic matter is 0.960. The correlation between total phosphor and ¹³⁷Cs is 0.851. Then, in the mic-landform (one slope) the soil organic conten and oil organic can be calculate and forecasted by measure the content of ¹³⁷Cs in the sample and never inspect them by chemistry means.4. in the whole research aera and one slope, The correlation between total nitrogen and ¹³⁷Cs is low (R<0.326), there are more reasns for the relations.5. By using GIS technology, we extract geographic information from a small part of research area, and the datas were translated using. GLOBMAPPER, SURFACE MAPPING SYSTEM software.Then, we display a 3D terrain model overlaying soil erosion modulus on the software of Openlnventor6.0 & Microsoft Visual++ by the soil erosion modulus configureing in the DEM spot. So the result furnish science gists for managing, preventing and cureing soil erosion and for biogeocenose continuable developingin the the research eara.