Research On Quarry Area Monitoring And Analyzing Using Landsat-based Long Time Series Images

Quarry sites result from human activity,which includes the removal of original vegetation and the overlying soil to dig out stones for building use,whose dynamics,therefore,reflect human mining activities from a special view point.Actually,the topographic changes caused by mining activities can been seen as a result of the local economy development.Thus,monitoring the quarry area can provide information about the policies of the economy and environmental protection.In this paper,Landsat images are used to obtain an annual monitoring result of a quarry area located in the boundary of Beijing,Tianjin and Hebei from 1984 to 2017,from which we developed a combined method of machine learning classification and quarry region analysis to continuously monitor quarry for a long period.First a modified random forest classifier was applied to each image and output a quarry classification result,then a temporal smoothing based on the classification results of all years was applied in post-processing to acquire finally quarry region.Next,based on the definition of margin region of quarry,only part of the area of this kind of quarry region is accounted in total area in order to reduce the impact of mixed pixels.A quarry distribution map and quarry area time series from 1984 to2017 were finally derived,revealing significant inter-annual variability.The time series revealed a five-stage development of the quarry area with different growth patterns.Based on the result,a comparison of the quarry area changes in the two jurisdictions was applied,which together with the analysis of social events revealed that the different policies in the two regions could impose different impacts on the development of a quarry area.For example,Beijing's Olympic Games and a serious landslide inside quarry region in 2008 lay a bad influence on the quarry activities to some degree,and when the quarry activities are restrained in one place,that in another place will keep increasing due to the moving in of quarry companies and truck drivers.An additional analysis concerning the relationship between quarry area and local GDP was performed to explore the potential application on socioeconomic studies,and we found a strong positive correlation(R~2=0.96531)before 2009 between quarry area and GDP in Langfang City,Hebei Province,which became much lower after 2009(R~2=0.30004).These results demonstrate the potential benefit of annual monitoring over the long-term for socioeconomic studies,which can be used for digging out the driven factors of quarry changes from a socioeconomic view.