Ecological Environment Evaluation Based On 3S Technologys In Gannan Prefecture

On the base of remote sensing and environmental data in of 2009, the evaluation system of "technical criterion for eco-environmental status evaluation" (HJ/T192-2006) and the method of 3S technologies, the ecological environment of Gannan Prefecture was evaluated in Gannan Prefecture.In order to overcome the disadvantages of traditional ways in acquiring ecological environmental data, the ecological environmental information extraction technology based on 3S was proposed and used in practical evaluation, which improved information extraction efficiency, shortened the information acquiring circle and enhanced the data precision.Due to the evaluation system in "technical criterion for eco-environmental status evaluation" focused on the county or larger area while ignored the differences in a region and could not reflect the actual situation of the study area, the evaluation unit which were the combination of vector surface evaluation units and raster point evaluation units was put forward by means of spatial statistical and analysis functions in ArcMap, the organism abundance index, vegetation coverage index, water network density index, land degradation index and environmental quality index of Gannan Prefecture in 2009 were calculated, and the ecological environmental quality of Gannan Prefecture and each county were evaluated. Results were as the followings:(1) The average ecological environmental quality index of the Prefecture in 2009 was 68.31,which meant that the vegetation coverage of this Prefecture was high, the biodiversity was aboundant and this region was suitable for human survival.(2) The ranking of average ecological environmental quality indexes of each county in 2009 from higher to lower was Diebu, Luqu, Zhouqu, Zhuoni, Xiahe, Hezuo, Maqu and Lintan. Among above five indexes, the organism abundance index and vegetation coverage index had highest influence to El, while the other indexes had minor influences to the final result because the general land in the Gannan Prefecture had light degradation. Luqu and Diebu which had higher organism abundance index and vegetation coverage index had higher EI. As for Zhuoni, because of the higher organism abundance index and vegetation coverage index but lower environmental quality index, El of the county was lower than above two counties. The distribution of industrial and mining enterprises in Xiahe, Hezuo and Lintan led to a lower El, and influence factor in Maqu was the grassland degradation. The results were basically consistent to actual situation.The final result of El was graded according to the methods mentioned in the "technical criterion for eco-environmental status evaluation", and the result shows that the poorer was 1%, usual was 10%, good was 64% and excellent was 25%. The percentage of counties with gradation above good was 98%, which meant that the general ecological environmental quality was good. The result could reflect the data and location of each gradation, which was beneficial to ecologic environmental management.