Remote Sensing Monitoring And Restoration Effect Evaluation Of Ecological Environment In Lingquan Open-pit Coal Mine

The open-pit mining of coal mines has not only promoted the economic development of our country,but also caused serious ecological and environmental problems.In recent years,the number of closures open-pit coal mines has been increasing year by year,but the ecological environment has not been fully treated after the closure of coal mines,resulting in land damage,slope instability,soil erosion and other problems.Therefore,ecological monitoring and restoration after the closure of coal mines have become the focus of current work.At present,the ecological restoration of open-pit coal mines in high-altitude and cold regions in our country is still in its infancy,and there is little research on the applicability and generalization of the evaluation system for ecological restoration effects.There are deficiencies such as imperfect index quantification calculation methods and immature evaluation index system.In response to the above problems,this thesis takes the Lingquan open-pit coal mine in Zhalainuoer District,a high-altitude region in our country as the research object,and conducts time series ecological environment remote sensing monitoring and ecological restoration effect evaluation,providing reference for subsequent ecological governance in the mining area.The main research contents and results are as follows:(1)Comparative analysis is conducted on the construction methods of time series remote sensing datasets suitable for Lingquan open-pit mine.In response to the problem of short vegetation growth period in high-altitude and cold regions,which makes it difficult to construct time series remote sensing datasets using remote sensing images due to time constraints,this thesis compares and analyzes three methods:spatio-temporal fusion model of sub pixel class fraction change information,neighborhood similar pixel interpolation image cloud removal method,and using Sentinel-2 images to compensate for missing Landsat data,and select a time series remote sensing dataset construction method suitable for the Lingquan open-pit mine.Through comparative experimental analysis,it is found that using Sentinel-2 images to compensate for missing Landsat data is more suitable for constructing time series images of the study area in this thesis.(2)The spatial and temporal dynamic change monitoring and driving factor analysis of fractional vegetation coverage in Lingquan open-pit mine.Based on the pixel binary model,the fractional vegetation coverage of the Lingquan open-pit mine for many years is inverted.According to the inversion results,the temporal and spatial changes of fractional vegetation coverage under the open-pit mining environment are analyzed,and the reasons for their changes are analyzed from four aspects:temperature,precipitation,soil properties,and human factors.The research results indicate that after the the mine closed in 2017,under the continuous ecological restoration project,the overall fractional vegetation coverage of the mining pit and waste dump has been significantly improved,and the main reason for the continuous increase in fractional vegetation coverage in the mining area is manual restoration.(3)The spatial and temporal dynamic change monitoring and driving factor analysis of soil moisture in Lingquan open-pit mine.Based on the normalized vegetation index and surface temperature,an NDVI-T_s feature space is constructed,and soil moisture information from the Lingquan open-pit mine over the years is retrieved.According to the inversion results,the spatio-temporal distribution changes of soil moisture between the open-pit mining period and the closed pit ecological restoration period are analyzed,and the reasons for their changes are analyzed from four aspects:temperature,precipitation,vegetation,and human factors.The research results indicate that during the period from 2009 to 2022,the soil moisture in the mining area has changed significantly,and the dry area has shown a decreasing trend year by year.The soil water retention capacity of the repaired mining pits and some waste disposal sites has been improved,and the ecological restoration work in the mining area has effectively improved the drought situation of the soil in the mining area,and precipitation is the main natural cause of soil moisture changes.(4)Establish an ecological restoration evaluation system suitable for the Lingquan open-pit mine in high-altitude and cold regions.On the basis of remote sensing ecological index,combined with the characteristics and actual situation of the mining area,four evaluation indicators are selected:vegetation coverage on the ground,soil and water conservation capacity on the ground,soil moisture and soil quality underground.An ecological restoration effect index is constructed based on the combination of remote sensing information and on-site sampling information,and is used to evaluate the ecological restoration effect of the Lingquan open-pit mine.The results indicate that the overall restoration effect of the mining pits in the research area is relatively good,while the restoration effect of the waste dump is relatively poor.In the later stage,it is necessary to continue to adopt artificial intervention restoration methods and manage them to improve their ecological restoration effect.