Researches On Environmental Quality Evaluation Index System And The Changes Trend Of 10 Years In GanSu Province

The ecological environment relates to human activities closely and is the basis of human survival. It not only provides the environment for human survival but also provides a variety of material needs for human society. Therefore, the ecological environment has a direct influence on the human welfare.The results of the research from 2000 to 2010 indicate that:1) Land use types distribution characteristics in temporal and spatial variation characteristics in cities and prefectures of Gansu province within the administrative area are not uniform. With the development of economy and the improvement of people’s living standard, urban land and rural resident land is increasing which the main development way both come from the grassland and arable land. Because of the factors of national policy, many areas in Gansu province begin to take returning cultivated land into forest and grass project, which makes the grassland, rural residents land, urban land and unused land present a dynamic balance.2) Convers in every level of the vegetation changes(2000-2010) have the positive and negative each other, but the overall positive changes are slightly larger than negative changes:the vegetation coverage is getting better, roll-in of one grade and two grade vegetation is higher than roll-out, it indicates that top vegetation area in the research area has been improved. The three level vegetation area decreases and mainly turns into the two level vegetation, that is to say that the vegetation is harnessed better. There is a mutual transformation between the four level and five level, inferior vegetation coverage turn better and then worse, but the overall the four lever vegetation destruction is more than governance. As a whole, vegetation coverage in Gansu Province showed a two-polar change in excellent and inferior trend during ten years.3) The soil erosion in Gansu is very serious, in 2000,2005 and 2010, soil erosion (do not contain no obvious erosion) area are 24872.9 km2,27503.6 km2 and 28000.8 km2, the main erosion intensity is mild and moderate erosion; soil erosion in different regions has a big spatial difference, the main erosion area is in the South of Gansu Province in the reasons of the uneven distribution in precipitation and the changes of land use type and landscape type Forest soil erosion area is the largest, next in meadow, as the main erosion area in Gansu province. Longnan mountain area, Gannan plateau and the Loess Plateau in Gansu are the main erosion landform soil erosion types; in addition, the uneven distribution in precipitation, the change of land use types and landform type, the human irrational use for the ecological environment are another important causes for the soil erosion.4) From 2000 to 2010 the rangeability of the ecological environmental quality of domain index in the province city is between-0.61 and 2.23, ecological environment in Lanzhou City becomes worse slightly, Tianshui and Dingxi ecological environment become better slightly, the other city states are no obvious change.