Study Of Land Damage And Recovery Remote Sensing Monitoring In Rare Earth Mining Area Based On Multi-source Sequential Images

As a very important strategic resource,ion adsorbed rare earth is widely used in all aspects of national life and has a very important value.Due to the limitation of mining technology,rare earth mining has brought economic benefits to the local area,but also brought serious environmental problems to it,such as land excavation,land occupation and desertification.Remote sensing technology is widely used in the monitoring of surface environment change because it can monitor the change of surface environment in real time and wide range.In this paper,we took Dingnan county and Xunwu County as the study area,and adopted Landsat TM,Landsat OLI,HJ-1B CCD and other multi-source image as the data source,using the regression analysis to establish the quantitative relationship between the NDVI of Landsat TM/OLI,HJ-1B CCD remote sensing image,we also build a unified standard multi source time series NDVI image on the basis of this,we study the temporal and spatial distribution of rare earth mining and the process of land damage and recovery in rare earth mining area through the NDVI change of time series,providing a theoretical basis for the ecological environment for the rare earth mining area,in order to better achieve the green sustainable development of the rare earth mining.The results of the research are as follows:1)We build transformation equation between NDVI of Landsat TM/OLI and HJ-1B CCD image based on regression analysis,the method of root mean square error is used to test the accuracy of the transformation equation,results show that the conversion equation has high accuracy,can realize the mutual transformation between the NDVI of Landsat TM/OLI and HJ-1B CCD data,it provides support for the change monitoring and analysis of multi-source time series images.2)Based on the related characteristics of rare earth mining,and also based on spectral information such as waveband reflectance of NDVI and SWIR1,Constructing NDVI mean value,coefficient of variation,mean value of the difference between NDVI and SWIR1,and other related parameters,combined with the CART decision tree,remote sensing timing analysis method,spatial analysis method to extract the rare earth mining on the study area.The results show that the accuracy of the method is higher,and the accuracy of user and mapping is higher than 80%.3)Analyzing the space-time distribution of rare earth mining based on the construction method in Dingnan county and Xunwu County,the results showed that:1990-2016 years,the overall change of rare earth mining area is:the first increased and then decreased,the change of rare earth mining area is influenced by national policy,influencing factors of mining technology,rare earth prices,supervision etc.year;Dingnan county and Xunwu County,the largest mining area respectively in 2006 and 2007,the mining area were 3.98 km~2,2.83 km~2.Dingnan County of rare earth mining is dispersed in the spatial distribution,to a certain extent,increased the difficulty of environmental governance.4)The analysis of land damage and recovery process showed that under the natural recovery condition,rare earth mining land recovery is slower,human activities can accelerate the recovery of mining land reclamation rate,is the main reason for vegetation restoration in mining area;after a long time of land reclamation,land reclamation rate of Dingnan County is53.04%,in Xunwu county is only 34.76%,and still there is a large area of rare earth mining area without artificial reclamation,It should arouse the attention of the relevant departments and reclaim in time.