Study On Remote Sensing Monitoring Of Eco-environment And Assessment Model Of Ecological Quality In Zhundong Mining Region

Coal trade is a pillar industry in Xinjiang,and coal reserves are abundant.However,the exploitation of coal resources will cause regional environmental problems such as land excavation,coal dust pollution,vegetation destruction and air pollution.How to quickly and accurately monitor the environmental pollution and evaluate the ecological quality is very important.Remote sensing technology is one of the effective methods to monitor the ecological environment parameters and evaluate the ecological quality in coal mine area.The Zhundong mining area was selected as the research area.Based on remote sensing image data during 2003²015 and ground measured data,the surface coal dust pollution status was monitored,and the diffusion rule was revealed.Vegetation coverage,land surface temperature,soil moisture,AOD,PM_2.5.5 and PM₁₀0 in air were estimated.By constructing the remote sensing ecological index and Analytic hierarchy process?AHP?,the ecological environment quality changes of Zhundong mining area before and after was assessing.It drew the following conclusion:?1?Remote sensing recognition and extraction of surface coal cover informationThe remote sensing classification methods?K-Mean,ISODATA?and non supervised classification methods?MD,ML and SVM?were used to classify coal dust pollution information on of Zhundong coal mine area.It was concluded that these classification methods could not effectively identify the information of coal dust pollution and distinguish the complex objects around the mining area.Through the comparison of multispectral and hyperspectral information,great differences in spectral reflectance curves of lump coal,coal dust and ground surface soil were found corresponding to the multispectral Landsat image NIR,SWIR1,SWIR2.SWIR1/SWIR2/NIR band-combined image could characterize the information of ground objects in coal dust pollution area,and identify the layout of various functional areas affected by coal dust.The construction of an enhanced coal dust index ECDI could effectively identify the coal dust information of typical cover types in the local mining area,while the water,soot and gravel would be distinguished.?2?Dynamic process and driving analysis of surface coal dust pollution informationThe spatial distribution of coal dust pollution in the past years in the Wucaiwan mining area was analyzed.The result showed that the coal dust reached the maximum in 2014 and decreased synchronously in 2015 and 2016.The migration and diffusion of coal was mainly caused by the mining process,transportation and stacking of coal and coal gangue.As the mining depth deepened,the transport distance was lengthened,and the diffusion of coal was slowed down with the disposal and transfer of the stack.The erosion of wind sand,the burial of dust and the erosion of rainwater caused the reduction of the area of coal dust cover.Coal settlement position mainly existed in southwest of the mine,which might be related with the influence of the northeast wind in summer,and coal gangue and coal washery surrounding closely.The coal dust settlement area was within 30 km range from the center of the mining area,and the closer to the center,the more obvious the pollution is.?3?Estimation and spatial and temporal distribution characteristics of vegetation cover based on remote sensingCompared with the dimidiate pixel model and trisection pixel model,the trisection pixel model was more suitable for estimating vegetation cover in arid desert areas.The vegetation coverage estimated by analysis of the NDVI-DFI model.It noted that The vegetation area of I and II levels in2003,2006,2009,2012 and 2015 showed a decreasing trend,that of III,IV and V levels showed an increasing trend.The model estimation of vegetation coverage had a significant scale effect.In local mining area of Wucaiwan,analyzing the mining activity intensifies,some of the NPV were occupied,and degenerated to BS.Because the area where the PV covered was smaller,the damage to the PV was lighter.?4?Estimation and spatial and temporal distribution characteristics of surface temperature based on remote sensingThe mine surface temperature estimation was performed by single window algorithm,the inversion results showed that the highest temperatures in 2003,2006,2009,2012,and 2015 were53.81,58.77,60.48,67.55,and 72.07,respectively.It showed a trend of increasing year by year,and the overall mean was increasing progressively.The desert area and Gobi formed"heat island effect",and the southern farmland formed the"cold island effect".According to the mining area in Wucaiwan,some temperatures of mining area had been influenced by the artificial influence.The LST in human activity area was generally lower than the unmanned area around Gobi,and relatively higher than coal mining area.?5?Estimation and spatial and temporal distribution characteristics of soil moisture based on remote sensingBy constructing the NDVI-LST feature space,calculating the dry edge fitting equation,the soil moisture in Zhundong was estimated by TVDI method.The value of soil moisture in each year was within the range of 0¹,mainly showing that soil moisture was lower in the middle desert,but higher in the southern oasis area and the Caramail Mountain area in the north.The TVDI means of2003²015 were 0.71,0.67,0.73,0.72 and 0.77,respectively,showing that the study area had maintained a high level of drought for many years.The results of TVDI in each year were different,and the distribution showed different characteristics of dispersion and aggregation.The moisture of some soil in the mining area was influenced by artificial influence.Precipitation type tendency of drought was in 2009 and temperature type tendency of that belonged to 2015,while the rest of the years had certain temperature or precipitation tendency type drought.The situation in each year was different,but was the decisive factor in aggregate.?6?Estimation and spatial and temporal distribution characteristics of PM_2.5.5 and PM₁₀0 based on remote sensingIn 2003,the relatively higher concentration and distribution of AOD were in the south,but in2006,they were distributed in the west,while no obvious distribution disciplinarian was found in2009 and 2015.In terms of the threshold,the AOD in the study area was at a lower level.The data values of PM_2.5.5 and PM₁₀0 are generally at a lower level by field measurement.Only a few observations were higher than the average of the national standard level II.The overall air environment was good.The correlation of PM_2.5.5 and PM₁₀0 with AOD and AOD*was very significant.Using the measured data and remote sensing data to establish a polynomial model to estimate the concentration of PM_2.5.5 and PM₁₀.The accuracy of the estimating model was improved by the vertical-humidity correction,showing that the R² was relatively increasing,while RMSE was relatively reduced.The model results showed that PM_2.5.5 and PM₁₀0 of high value areas were mainly distributing in the southwest of the study area,the oasis and desert ecotone in Fukang.The maximum values of PM_2.5.5 and PM₁₀0 were more than the daily average value of the national standard two,but mean values were not.The linear fitting between the measured value and the predicted value showed that it was feasible to retrieve the data of PM_2.5.5 and PM₁₀0 by the inversion of the aerosol with a good effect.In contrast,PM_2.5.5 had a better prediction effect than PM₁₀.The frequent sandy weather in the southern part,and the relatively higher particles in the air caused of the more PM_2.5.5 and PM₁₀0 in the south of the study area.In addition,there was a positive correlation between temperature and them,while a negative correlation between relative humidity and them,however,they were not significant.?7?Ecological quality evaluation index system based on RSEI and AHPCorrelation analysis of coal dust pollution degree,vegetation coverage,land surface temperature,soil moisture,PM_2.5,PM₁₀0 showed that coal dust had significant correlation with f_PV,LST and TVDI.Coal dust had a negative effect on plant growth,and the surface temperature of coal dust polluted areas was relatively high.The f_pvv had a significant negative correlation with LST and TVDI.PM_2.5and PM₁₀0 maintained a high correlation,and also had a significant negative correlation with LST and TVDI.From the results of RSEI,the order of the ecological system from good to bad was middle desert area,oasis desert ecotone,oasis area.The areas of severe air pollution were generally near the oasis and oasis desert ecotone.From AHP,the largest proportion of the ecological environment quality grade in each year was bottom grade,which accounted for 70%⁸5%of the area of the study area.The smallest proportion of that was top grade,while area ratio was less than1%.The middle grade was mainly distributed in the oasis area and being better,while the bottom grade went worse and was more sensitive and easy to fluctuate.The overall ecological environment was being better from 2003 to 2015.The change of the southern oasis area was more obvious.There was a large area of arable land in the northeast corner mountain and the southwest corner,showing that the ecological environment in these areas tended to be relatively stable and had little change.In addition,the ecological environment in the desert and Gobi had been improved.The pollution on the ecological environment in small scale of Wucaiwan area was heavier than that in large scale of Zhundong coal mining.There are certain differences and generalities between the two methods of evaluation.The adaptability of RSEI to sparse vegetation areas in arid desert is weak,but its operation is simple,objective and easy to be realized.The application of AHP to ecological evaluation is more ecological.It is suitable for the study area,but the requirement of the index is too high and there is certain subjectivity.To sum up,coal mining has little influence on the large scale of ecological environment in Zhundong,but has great influence on the small scale of ecological environment in Wucaiwan.Human activities have an important influence on the ecological environment parameters of the mining area.With the ecological restoration of mining areas continuing to strengthen,the ecological environment will be improved in Zhundong coal mine.