A Study On Ecological Security Evaluation Based On Grid GIS

The geographical information technology is the result that geographical systematic science combined with information technology. It is the organic combination of technology such as remote sensing (RS), geographical information system (GIS), the global positioning system (GPS), and network (Web), etc. It regards GIS as the core, taking RS and GPS as the important information source, and Web as important information gathering and sharing tools. Born in the sixties of the 20th century, after more than 40 years of development, functions of GIS, such as data-collecting, data-storing, data-managing, data-inquiring, data-searching, and visual output, etc., are becoming more and more perfect. It is widely applied in the fields of ecological environment research and so on, and has achieved outstanding results. The grid GIS technology is the organic integration of old maps thoughts and modern grid information technology. The formation and development of the technology of grid have injected new vigor into GIS even more, which makes the precision of GIS application study improved greatly.In recent years, with the problem of global ecological environment emerging day by day, the mankind begins to care about the problem of ecological security. And people located it at the same important position as political security, military security, economic security, scientific security and so on. As the foundation and carrier of other security, ecological security extended the notion of national security. The ecological security evaluation can make the mankind realize ecological environment of them in current situation, regulate and utilize the ecosystem function to serve for the mankind development rationally. So the ecological security evaluation is necessary to meet the need of human development under the new forms, too.The importance of the ecological security evaluation requires the mankind to use existing advanced technology to carry on accurate appraisal to the security of current ecology situation. It is owing to powerful function of GIS to collect, analyze and manage data that enables it to offer essential technical support for the research work of ecological security evaluation. The introduction of the grid GIS technology makes GIS application study in the field of ecological security evaluation enters into a new stage again. So, the author introduces the grid GIS technology into the field of ecological security evaluation; and carries out the exploration of grid GIS theoretical research. Taking the ecological security evaluation of grassland in pastoral area of Gansu as an example, the author carries out the empirical research, which testifies the feasibility of this research thought.This thesis described relevant theories of grid GIS and ecological security firstly, based on which the author introduced the relevant contents of grassland ecological security and its evaluation, and taking the ecological security evaluation of grassland in pastoral area of Gansu as an example, the author carries out the empirical research. In the course of whole research, the key points and difficult points of study is the construction of the evaluation index system and it's gridized, the build of the appraisal model, and the calculation of the evaluation index weight. While constructing index system, the author referred to the theory of the frame model of ecological security evaluation, namely, State-Pressure-Response; and carried on on-the-spot investigation in the typical area, relevant information collected and literature searched. Combining the principle of choosing evaluation index, the author structured the multi-level index system of ecological security evaluation in the grassland. On the basis of analyzing each evaluation index characteristic and its relevant factors, the author realized that every evaluation index has been gridized by adopting certain mathematics method. The model used in the study is a comprehensive appraisal model, adopting Entropy-right Method confirmed objectively every weight of evaluation index, and reduced the influen...