| The ecological environment of arid and semi-arid mining area is fragile,and the influence of human disturbance makes the study on the change of ecological environment a hot topic.Ordos City in Inner Mongolia Autonomous Region is in the convergence zone and the transitional zone of agriculture and grazing in central and western regions.It not only assumes the role of ecological barrier,but also an important energy city and coal base in our country.It is also an important base for ecological protection and governance of the country.It is of great significance for regional sustainable development and ecological security to accurately evaluate the law of ecological environment evolution in the study area.Based on the research area of Ordos City,this thesis adopts the method of RS and GIS to acquire multi-source remote sensing data,and carries out the research on the ecological environment change of arid and semi-arid mining area.Firstly,the ecological remote sensing index（RSEI）was used to calculate the greenness,humidity,dryness and heat of the study area during 2000-2020,and the temporal variation of ecological environment quality in the study area was analyzed by principal component analysis and hierarchical processing.Then,the precipitation erosivity factor R,soil erodibility factor K,slope length factor L,slope factor S,vegetation cover and management factor C,and soil and water conservation measure factor P were calculated.The modified RUSLE model of general soil loss equation was used to analyze and evaluate the distribution and change of soil erosion in Ordos City and mining area in a long time series to characterize the ecological vulnerability of the study area.Finally,starting from the natural factors and social factors,the factors affecting the ecological environment in the study area were analyzed,the MRSEI index was constructed,and the impact boundary of the ecological environment in the mining area was defined through superposition analysis,and countermeasures and suggestions were given for the ecological governance of the mining area.The main conclusions are as follows:（1）During the study period,the average RSEI of Ordos in 2000,2005,2010,2015 and 2020 were 0.1893,0.1547,0.1803,0.2087 and 0.2302,respectively.The overall ecological environment of Ordos was poor but developing in a good direction.Compared with the whole city,the ecological environment of the mining area was better.The mean RSEI of Shendong mining area were 0.2737,0.2808,0.3643,0.3277,0.4246,and the mean RSEI of Junge mining area were 0.3556,0.3765,0.3885,0.3802,0.4501,showing an obvious trend of improvement year by year.Through the analysis of the mean value and spatial distribution characteristics of the four indexes,it can be seen that greenness and humidity had positive effects on the eco-environmental quality of the study area,but drying and heat had opposite effects.The movement of the center of gravity of RSEI in Ordos City presented a trend of"first to northeast,then to southwest,and overall to northeast".The spatio-temporal evolution of RSEI in the study area was analyzed in two periods from 2000 to 2010 and from 2010 to 2020.The results showed that the ecological environment of Ordos City and the two mining areas had been optimized and achieved positive development.（2）In the past 20 years,the soil erosion in Ordos City and mining area was mainly mild and mild.The average soil erosion in Ordos City in 2000,2005,2010,2015 and 2020 was 3553.59 t·km-2·a-1,2658.09 t·km-2·a-1,3449.52 t·km-2·a-1,3317.00t·km-2·a-1,3480.48 t·km-2·a-1,respectively.Soil erosion fluctuated up and down.Considering the substantial increase of human activities,the soil erosion in Ordos City had undergone benign changes on the whole,and the ecological environment was developing in a good direction.The soil erosion of Shendong mining area was better than that of Ordos City,while that of Junge mining area was on the contrary.Overall,the ecological vulnerability had been reduced.Based on the standard deviation ellipse model,the movement of soil erosion gravity center in Ordos City presented the changing trend of first west,then east,first north and then south.The temporal and spatial evolution of soil erosion in the study area was analyzed in two periods from2000 to 2010 and 2010 to 2020.The results showed that the ecological environment vulnerability of Ordos City and the two mining areas had decreased,and the ecological environment was in a good direction.（3）Based on superposition analysis and geographic detector model analysis of the main factors affecting the evolution of ecological environment in Ordos City,the results showed that vegetation coverage was the dominant factor.By comparing the explanatory power of natural environmental factors and human factors,it can be found that natural environmental factors were the main reasons affecting the spatial distribution of ecological environment in Ordos City.The synergistic effect between the factors enhanced the explanatory power.Low vegetation coverage area,steep slope area,industrial and mining land and other land use areas had higher ecological risk.Coupled with five ecological factors including greenness,humidity,dryness,heat and soil erosion,MRSEI index was constructed to define the ecological environment impact boundary of arid and semi-arid mining areas.The impact boundary of Shendong mining area was identified as 1700 meters,and the impact on the ecological environment was severe within 470 meters.The effect of Shendong Mining area on the ecological governance of the mining area was remarkable.It was recognized that the impact boundary of Zhunge mining area was 3500 meters,and the ecological changes were severe within 1500 meters.Relevant departments should strengthen the ecological restoration and management within this range.Ordos City can be divided into mountainous region in west,loess region in east,sandy region in central south and soil sensitive area in mining area to deal with ecological environment changes effectively. |
PDF Full Text Request