| BACKGROUND:The Qinghai-Tibet Plateau, the resource of Changjiang River and Yellow River, which is the cradle of Chinese civilization, is explained as"Chinese water-tower"and"the third polar of the world", and has an important influence on the global environment and climate. However the current situation of the Plateau's environment and ecology is not optimistic and anxious, with a trend of"serious soil and water loss, land desertification and exhaustion of water resources".Tibet is the main part of Qinghai-Tibet Plateau, there are limpid rivers with good quality water, magnificent environment with outstanding original ecology characteristic.and clean atmospheric environment which has never acid rain and radioactive contamination. The special humanistic and geographical environment provide favourable condition for Tibet's exploitation, economy development and society progress, all this make Tibet become a travel resort for people. However, Tibet's geographical environment is very particular, 86.1% lands are located above the elevation 4000 meters. Influenced by the alpine and bad natural condition, the ecological environment of Tibet is extremely fragile, once it was destroyed, it is difficult to recover.The problems of Tibet environment mainly shows in the aspects as follows: serious grassland degradation, serious soil erosion and land degradation, low-level and asymmetric forest coverage, frequent geological hazard and glacial recession.As an important parts of environment science, eco-environment evaluation has been a key issue of present research. However, there are still many problems for eco-environment quality evaluation, such as multiple methods and various index systems.On the basis of introduction the theory of environment and ecology quality evaluation, author analyzes the advantage and disadvantage of each kind of evaluation method and describes the suitability. Their applicability and relationship are explained and analyzed for research about way of eco-environment evaluation. Combining thinking of Tibet environment problems and the characteristic of ecosystem, idea of"Flux and Flow Direction Assessment of Ecological Environment"was put forward. Finally, taking Tibet ecology appraisal as an example, the author developed the theory research and practice works.OBJECTIVE:The paper is intended to combing the system of ecological environment evaluation theory and method; illustrating the concept, theory, method and realization technology of"Flux and Flow Direction Assessment of Ecological Index"(FFDAE); Based on compound analysis of remote sensing data and other data, author analyzed the change of ecological environment elements of Tibet in the past 30 years, studied the ecological environment of Tibet by flux and flow direction Assessment using RS and GIS technology, and finally offered reasonable scientific reference for resource utilization and environmental protection.METHODS:In the foundation of teacher's topic, choose the ecological environment of Tibet Autonomous Region as research object, and utilize the theory and method of ecological environment evaluation to develop the research as follows:In view of the fact that the ecological environment evaluation system is complex, lacks of the unification theory system and analysis method, and the obvious regional and individual tendentious characteristic in the former appraisal process, it is not favorable for the development of ecological environment evaluation and dynamic monitor. Therefore, combine the theory and method system of the environmental evaluation firstly, then analyze the characteristic of remote sensing technique, the GIS technology and the eco-environment evaluation technology, and lastly analyze ecological environment assessment method system to divide the eco-environment evaluation system.Applying the GIS network analysis and hydrographic station monitor thought in the ecological environment evaluation, proposed the eco-environment evaluation mentality of"Flux and Flow Direction Assessment of Ecological Index", carried on exposed analysis to different channel's ecological environment factor, based on this, expounded the correspond thought of"Flux and Flow Direction Assessment of Ecological Index", and applied the ecological environment evaluation RS-GIS coupling technology to analyze and give the suitable evaluation type, target model and computing technique for each kind of the environment current capacity flows to the evaluation thought. Based on the environmental factor which involves in the ecological environment evaluation, using the 3S integration technology to withdraw and process the ecological environment factor of Tibet, take GIS as the foundation platform, carried on the management, the dynamic access and the spatial analysis of many kinds of data, supplied the special information of environment factor with RS, and carried on the data updating for GIS promptly.Based on ecological environment's present situation and the environment pressure for Tibet, constructed index system and technology method of ecological environment evaluation, based on connotation of different evaluation content, in view of ESA constructed"P-S-R"frame index system, in view of EHA designed"human– nature - limit"index system, in view of ESFA used"structure– density - quality"index system, in view of ECCA, constructed"the pressure index - ecology load bearing index"frame, in view of GEQA proposed"L-N"pattern, in view of CEQA proposed"ESAI-ECCAI-ESFAI"index system; Respectively using comprehensive evaluation method, AHP method, polygon comprehensive evaluation method ,"L-N"method,triangle evaluation method and so on, realized Tibet's ESA, EHA, ESFA, ECCA, GEQA, CEQA, and quantified Tibet's ecological security, ecology capacity price, ecology health from various aspects. In the process of index construction, insisted the remote sensing technique for the core basic philosophy, safeguarded the evaluating indicator considerably as far as possible.COMPARISONS WITH REVIEWED RESEARCHES:Compared with reviewed researches, the innovation and characteristic of the paper is as follows:1. Based on comprehensive arrangement of previous study results and analysis of each ecological environment evaluation, proposed division scheme of eco-environment evaluation theory system first time, analyzed and interpreted them by revealing the relationship among them, and carried out the eco-environment evaluation on the guidance of the theory and method.2. Applied GIS network analysis and hydrographic station monitor thought in the ecological environment evaluation, proposed the eco-environment evaluation thought of"Flux and Flow Direction Assessment of Ecological Index", based on the fundamental theory of ecological environment, gave correspondence evaluation theory and method of"Flux and Flow Direction Assessment of Ecological Index";3. Start from the concerned environment problem, applied fundamental theory of ecological environment evaluation and"Flux and Flow Direction Assessment of Ecological Index", carried out ecological environment sketchy evaluation, ecological environment special subject evaluation, ecological environment comprehensive evaluation first time in the Tibet Autonomous Region, involved several topics, such as ecological security evaluation, ecology supporting capacity evaluation, ecology health evaluation, ecology service function evaluation and so on;4. Using the information excavation technology extracted index, established regional ecological environment evaluation frame system and the basic evaluating index. in view of ESA constructed"P-S-R"frame index system, in view of EHA designed"human - nature - limit"index system, in view of ESFA used"structure - density - quality"index system, in view of ECCA, constructed"the pressure index - ecology load bearing index"frame, in view of GEQA proposed"L-N"pattern, in view of CEQA proposed"ESAI-ECCAI-ESFAI"index system; Respectively using comprehensive evaluation method, AHP method, polygon comprehensive evaluation method ,"L-N"method,triangle evaluation method and so on, realized Tibet's ESA, EHA, ESFA, ECCA, GEQA, CEQA, and quantified Tibet's ecological security, ecology capacity price, ecology health from various aspects.5. Furthermore, according to the characteristic of different evaluation type in Tibet, used different index system and evaluation model, embodied the universality and comparability of evaluation index in a way.6. In the process of ecological environment safety evaluation, based on different evaluation unit designed different evaluation method, combined raster spotty evaluation unit, administrative region, natural region and artificial division unit with each other, developed multi-criteria study of ecological environment evaluation to make the evaluation results and division more accurate and the topicmore outstanding.7. Considering the function of RS and GIS technology in ecological environment evaluation, discussed how to service for ecological environment evaluation using RS technology and provided some fast, dynamic and real-time environment element indexes (data). Established the relationship between lake change, the source region normalization vegetation index(NDVI) change and the ecology geological environment evolution, proposed the"L-N"method"ecology geological environment evaluation of lake and NDVI remote sensing dynamic monitor", carried on experimental analysis and discussion in Qinghai-Tibet Plateau. CONCLUSIONS:Ecological environment evaluation can be divided into two aspects: the ecological environment quality evaluation and the ecological environment influence evaluation. Ecological environment quality evaluation includes three levels: environment quality sketchy evaluation, ecological environment quality special evaluation and ecological environment quality comprehensive evaluation. Ecological environment quality special evaluation includes ecological security evaluation, ecology health evaluation, ecology risk evaluation, ecology vulnerability evaluation, ecology service function evaluation and so on; Ecological environment quality comprehensive evaluation needs many aspects of environment characteristics such as ecological environment security, health, risk, frailty, service function for reflection. Ecological environment influence evaluation has two aspects, which is used to evaluate the human factor influence ecological environment and natural factor influence ecological environment in separately.Flux and Flow Direction Assessment of Ecological Index is the further development of ecological environment evaluation method, its concrete evaluation method is determined by the flow and flow direction of the environment index, and the evaluation method and theory are the continuation of the ecological environment evaluation. It's different from conventional evaluation model, for it stresses the evaluation of the relationship between environment factor and ecological environment in simple unit, moreover when calculated the environmental index, its influence data value and change direction indicated that ecological environment protection and resources development are more prominent. The practice proved that this method is feasible and exercisable.Flux and Flow Direction Assessment of Ecological Index ties up the ecological environment evaluation index system and the corresponding channel, strengthened the universality and feasibility of evaluation index.Looking from Tibet Autonomous Region's ecological environment evaluation, it still held original ecology ecological environment in the area, however various aspect stress level that it faced started to increase, ecological risk existed.Ecological security of the most Tibet Autonomous Region cities is relatively stable or increased, compared to 1986, ecological security of the Tibet Autonomous Region increased slightly, number of cities whose ecological security enhanced significantly can reach 37, accounted for 47.44 percent of the total number of cities.Compared to 1986, ecological health status of Yarlung Tsangpo River watershed has improved on the whole. Improvement area mainly concentrated in the middle upstream of Tibet of the small watershed whose number was 3, 7, 8, 11, 16, 17, 18, 20, 21, 23 and 25. Area of health quality decreased mainly concentrated in the downstream of Tibet of the small watershed whose number was 9, 13, 24, 29, 34, 35, 37 and the 19 small watershed in the upstream, and other watershed is in stable status basically.Ecological capacity of Tibet was strengthened from the west to the east, band area of Gongbujiangda, Bomi and Changdu as center, with the development of economy and improvement of the population quality, social progress, enhancement of people's awareness of environment protection and precipitation increase, in the middle of Tibet, such as Nima, Bange and Xigaze and so on, ecological capacity has improved.The total value of ecology service in Tibet Autonomous Region was 13.968 billion dollars, according to current exchange ratio (1 dollar exchange 6.99 RMB), equivalent to 972.784 billion RMB, the value of ecology service is considerable, and it has significance in the development of Tibet as well as the whole country. However, area of Tibet Autonomous Region is 8‰of the global land area, the total value of ecology service is only 4‰of the global, which is related to the desertification aggravation, relative low vegetation coverage and poor environment. In addition to the direction of Xigaze to Dingqing,quality of the ecology environment has declined, most parts of other area has relatively improved compared to 1986.The ecology geological environment of the Qinghai-Tibet Plateau overall assumes the worsened tendency, the plateau northern boundary zone, the Yangtze River system upstream, especially the Qaidam Basin is more obvious, Yarlung Zangbo River basin, southeast of the plateau is good;"L-N"method is helpful in improving the efficiency of remote sensing environmental monitoring, the lake, the NDVI remote sensing monitor has an important ecology geological environment significance.MEANINGS:Through the RS-GIS ecological environment evaluation's combination and integration technology, it realized the ecological environment safe research digitization, informatization and visualization, analyzed and divided the theory system of ecological environment evaluation. Based on different environment channel developed different type of ecological environment evaluation, used different evaluation index and method, and expressed the quantity and direction of each kind of ecological environment index. This achievement has theoretical and certain innovative work in the ecological environment evaluation study domain, provided a new mentality and method for the research of region ecological environment problem.However, there are still many problems to be researched in the field of ecology environment evaluation, if its theory method can be further consummated, and formulated simple, practical and feasible, strong universality evaluation method, it is advantageous in the contrast of ecological environment evaluation project and research.he remote sensing technique has the characteristics of strong macroscopic property, abundant information, prominent dynamic monitor ability and so on, which is the assistant of landscape ecology environmental evaluation method. If design a series of indexes available from RS technology based on the ecological environment evaluation theory, combined the digitalization, informatization, systematization and visualization humanities material, it will certainly push the ecological environment evaluation and research work into a higher level."L-N"method mentioned in this paper is a preliminary attempt in this aspect.
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