Study About Ecological Fragility Evaluation In Wanzhou District Of The Three Gorges Reservoir Area Based On The "3S" Technology

The Three Gorges Reservoir area is a typical ecological fragile areas of China. The ecological system of The three gorges reservoir area becomes more special and complex because of its special natural environment and a series of problems about rapid population growth, serious pollution and so on which comes from the construction of The Three Gorges Reservoir and rapid development of society and economy. The unreasonable human activities caused serious consequences on the ecological system of the Three Gorges Reservoir area, and adverse effect on the safety of the Three Gorges Project and the lower Yangtze region and sustainable development of society and economy in the Yangtze River Basin. In addition, Wanzhou district is a typical area and in the center of the Three Gorges Reservoir Area, also they have the high similarity on the topography and geomorphology. What’s more, Yangtze River runs through the whole area, and after three times of water storage in the Three Gorges reservoir, the flooded area and the scale of immigration are very huge in Wanzhou, also the regional ecological environment changed dramatically.Taking wanzhou as the research object, using the Landsat TM remote sensing data, environmental monitoring data, social and economic data of Wanzhou as the basic data source, under the support of 3s technology, this article established the evaluation factor database and the index system of ecological fragility in Wanzhou, and determined the weights of evaluation indexes, and evaluated the Wanzhou on the side of ecological sensitivity and ecological resilience and ecological pressure with the method of special evaluation method, then evaluated the ecological fragility in Wanzhou with the method of comprehensive evaluation method, and analyzed the characteristics and the distribution rule of ecological environment. The results showed:(1) The average ecological sensitivity index(ESI) is in the middle or slightly low level, and there are differences in the spatial distribution in Wanzhou. The lighter sensitive area is mainly distributed in the portion of the boundary of the Wanzhou; the light sensitive area is relatively evenly distributed in the study area and is widely distributed; the moderate sensitive area is mainly distributed in the southeast and southwest foothills of the Wanzhou; and the high sensitive area is mainly distributed in high altitude mountain in Wanzhou with strip distribution,it needs special attention.(2) The whole ecological elasticity index(EEI) of Wanzhou is in the middle level, and the spatial distribution has certain regularity. Ecological low elastic area are mainly distributed in high altitude mountain with complex terrain and relatively low vegetation coverage; ecological moderate elastic area of is relatively evenly distributed in the central hinterland of the study area; and ecological high elastic area mainly distributed in relatively low altitude area along the Yangtze River.(3) The ecological pressure index(EPI) in Wanzhou is in the little higher than medium level. High ecological pressure area is distributed in the north central area (county and the surrounding township) with economic development and dense population of the study area, and Shuang He Kou Street is facing the biggest ecological pressure; moderate ecological pressure area mainly distributed in the central hinterland with medium population density level; low ecological pressure area is mainly distributed in western and eastern edges of Wanzhou. Also the average ecological pressure index of the whole study area was 47.37, which is in the little higher than medium level.(4) The ecological fragility index of Wanzhou is in moderate level as a whole, and the spatial distribution has certain regularity. From the side of ecological fragility classification, there are no ecological very low fragility and very high fragility area in Wanzhou, the spatial pattern of ecological fragility distribution presents the characteristics of higher in north lower in south, high fragility area concentrated in the economically developed regions with low vegetation coverage in Wanzhou; also low fragility area is mainly distributed in the northwestern and southeastern mountain with good ecological environment, under-population, and high vegetation coverage.