Research On Remote Sensing Monitoring Of Soil Environment In Coal Mining Subsidence Area

Northwest arid desert as our country important coal exploitation area,vegetation degradation,has serious land desertification phenomenon,due to the large-scale mining of coal mine,local originally fragile ecological environment is facing more serious situation,surface subsidence,ground fissure,groundwater and other geological disasters caused by the local vegetation and soil moisture changes,cause serious harm to the local ecological environment.The change of the mining area ecological environment is dependent on the local vegetation and soil moisture,so in order to study the mining subsidence area of vegetation,disturbance of soil moisture,based on the coal base in east Ningxia as the research area,from the scale of coal mine and mine scale,based on microwave,optical remote sensing data of 2016-2018,for coal mining subsidence area and depth data such as dynamic change process.A TVDI model based on Ts-NDVI method was established to monitor the variation characteristics of normalized vegetation index and temperature vegetation index in the mining area,and then the subsidence and non-subsidence areas were analyzed on a spatial scale for comparative analysis.Finally,the results of surface subsidence deformation and failure are analyzed in depth,and the following conclusions are drawn:(1)Yang Changwan coal mine and coal mine subsidence of Mei Huanjing have obvious subsidence.During the research period,the average mining strength of local coal mines remains roughly the same,and the maximum vertical displacement tends to be stable.However,there is a significant increase from October to November,and a slight decrease from January to February,2018.By means of mutual verification of DInSAR and SBAS-InSAR,it is concluded that the deformation monitoring results of DInSAR data based on the research time interval can basically qualitatively reflect the change situation and trend of the surface.(2)NDVI of Ningdong Coal Base shows a phenological cycle change on the whole,and the seasonal fluctuation of surface soil moisture after mining subsidence in Yang Changwan mining area is more obvious than that in adjacent non-subsidence affected areas,and the results of vegetation and soil moisture show a significant spatial correlation between mining area scale and mine scale.(3)The soil moisture in summer is relatively low,whereas the soil moisture in winter is relatively higher,which is consistent with the changes in the mining area.The NDVI values in the non-subsidence areas were significantly higher than those in the subsidence areas,and the change of vegetation index in the subsidence areas was significantly higher than that in the previous year.The NDVI values in 2019 were the lowest,2018 was the highest,and 2017 was the next,all of which showed a trend of increasing first and then decreasing.(4)The mean temperature vegetation drought index change is more positive,and the degree of change is growing,especially in 2019,the average TVDI change than general maximum,average changes in April,A deformation area ratio reaches 79.40%,that had significantly lower when the soil moisture,it should be because squarely in the spring,and the effect in mining subsidence area,so the soil moisture decrease.(5)Both the non-subsidence area and the mean value of the subsidence area are higher than that of the subsidence area,which also proves that mining has a negative impact on the local ecological environment,and TVDI is greatly affected by mining.The value of TVDI in the subsidence area showed an increasing trend for three years,indicating that mining had a great impact on soil moisture,which should be weakened later.The mean maximum value of TVDI in the non-subsidence area was consistent with the overall variation trend of the mining area within three years,which was in line with the growth rules of local vegetation.(6)Through the analysis of the impact of coal mining disturbance damage,surface damage and slope on the ecological environment of the mining area,it is concluded that mining activities fully reflect the changing effect of surface soil environment caused by coal mining subsidence,so as to provide theoretical and technical support for disaster prevention,ecological restoration and environmental protection in the mining area.