| West-East natural gas transmission project has a significant influence on ecological environment, because the project has large region, complicated geological conditions and fragile ecological environment in the northwest of China. Nowadays, ecosystem stability evaluation has been usually used to evaluate the influence on ecological environment. Ecosystem stability can show the ability to resist external interference and the recovery ability after disturbance. In order to evaluate the ecological environment along the pipeline and to provide suggestions to pipeline ecosystem protector. In this study, we have made the pipeline ecological evaluation model to give the quantity evaluation of ecosystem stability.There are many factors which affect the stability of ecology. According to the ecological characteristics of the northwest of China, the main evaluation index including soil, climate, plants and surface topography were selected in this thesis. Soil utilization types and soil types were included in the soil index. The climate index contained annual precipitation, annual strong wind days and the sum of days which average air temperature equal to or greater than 10℃. Plants index contained vegetation coverage and vegetation index. Topography index contained slope and aspect.When the index systems have been completed, we have referenced Technical code on soil and water conservation of development and construction projects, the regional environmental geology survey conditions(trial) and some other standards. Then expert scoring method was used and the classification standard to quantify the index was set up.Model of weighted summation which is mostly used in ecological model field had been used in this study. The ecological function zoning interim procedures published by Environment Protection Administration and some other references had been considered in the model. Finally, ecological quality, water erosion sensitivity and wind erosion sensitivity were selected as the index model to build the ecological stability model. The indexes of ecological quality model include soil, dryness, slope and plants. The indexes of water erosion sensitivity model include slope, aspect, soil types and the used type of soil. The indexes of wind erosion sensitivity model include soil types, annual strong wind days and dryness.The index system and the model were applied to the pipeline data of JingBian city in ShaanXi province. The ecological status chart was drawn and given the stability evaluation of ecological system. The model makes it possible to dynamics combine the ecological model with GIS.The results show that forest area where the pipeline passed has the best ecological stability, while the desert area has the worst. These results accord with the reality. The accuracy of model with high degree of visualization and quantification is verified by the true data of pipeline of JingBian city. |
PDF Full Text Request