Dynamic Monitoring And Evaluation Of Eco-environment Based On 3S Technology In The Northern Of Shaanxi Province

Soil erosion and restoring the eco-environment has been the focus work of the northern of Shaanxi province. Returning cropland to forestry (grass) has been taken many years.The government want to know the progress and effectiveness of the project.If the government know these data, the planning of the project will be rationally adjust. In order to solove the problem, the methods which can quickly mornitor the eco-environment of the large area is needed. In this paper, the operational method based on 3S techonology was studied in the 1997 and 2004, this method will be apply to return cropland to forestry (grass).The study includes five steps: 1. Based on the sample points from GPS, these TM images were claasfied by supervised classification. The landuse and change information were acquired of 1997 and 2004. 2. The slope information was acquired from the digital elevastion model.The slopeland and soil erosion was acquired by the analysis of overlay and clump.3. The spatial changes of characteristics were studied.4. Based on mornitoring results, Analytical Hierarchy Process was used in the evalution of ecological ecvironment. In the study, some indicators were considerd, for example, climate, pollution, water, vegetation and so on. 5. The function of climate was anylyzed.The result shows:1. The effectiveness of returing the cropland to forestry (grass) was quickly monitored by using the method. The method offers the reference of the operational works, and can be applied for the return the cropland to forestry (grass).2. The result of dynamic monitoring shows: (1) The effectiveness of returning thecropland to forestry (grass) is significant, and the area of cropland was decreased. The primary decrease concentrated on the slope farmland and most of which occurred in the grade of >15°. (2) The quality of ecological environment was improved, and has shown a clear geographical diversity. (3) The analysis of the climate shows that the climatic condition from 1997 to 2004 was more suitable for the restoration of vegetation. That is, the climatic condition played a certain role.3. The result of this study offered objective, detailed and rich data for return the cropland to forestry (grass), and provided the scientific basis for the planning and decision-making of the project. And the result also found the problem of the project, based on the problem, the planning of the project will be adjusted, so the implementation of the project will better rational.