Fractional Vegetation Cover Information Extraction And Analysis Of Temporal And Spatial Variation In Huolinhe Open-cast Coalmine

Fractional vegetation cover is an important parameter to describe the growth status of surface vegetation,and it is also a key indicator to characterize the change of ecosystem.Remote sensing technology has the advantage of small time span and wide coverage,which can effectively monitor the regional vegetation change.Due to its various characteristics such as high spectral resolution,numerous bands and continuous spectrum,hyperspectral remote sensing can obtain the fine spectrum of complex objects.It has obvious advantages in vegetation identification and classification research,and becomes a powerful research tool in the field of vegetation cover extraction.The open-cast coalmine of Huolinhe which is China's largest open-cast coalmine,but it's environmental ecosystem has been damaged seriously.It is of great significance to study the change of vegetation coverage in Huolinhe open-cast coalmine to realize the coordinated development of mining area and ecological environment protection.This paper summarized the research status of hyperspectral remote sensing and vegetation cover extraction both at home and abroad,and selected HJ-1A-HSI hyperspectral remote sensing data as the main data source.Firstly,according to it's characteristics,we completed the basic data preprocessing,including: format conversion,absolute radiance conversion,effective band selection,fringe removal,atmospheric correction,image mosaicing and clipping.Secondly using local linear embedding dimensionality reduction method to reduce the dimensions of HJ-1A-HSI hyperspectral data,effectively removed the quantity of the original data,meanwhile retained the effective information.Thirdly based on the Pure Pixel Index,the optimal endmember extraction was completed by taking account of three indexes: Count_Based/Count_Based Index,Endmember Average RMSE,and Average Spectral Angle.Fourth the fractional vegetation cover of the study area was extracted from 2009 to 2015 based on Multiple Endmember Spectral Mixture Analysis(MESMA)model.The results show that MESMA is feasible to extract vegetation coverage information of typical open-cast coalmine.Finally from the perspective of climatic factors,we analyzed the causes of vegetation coverage change in Huolinhe open-cast coalmine.The results of vegetation cover extraction showed that the annual change of vegetation coverage in the whole Huolinhe open-cast coalmine from 2009 to 2015 is not obvious,which is basically within the range of 4%.At the vicinity of the boundary,the variation range of fractional vegetation coverage is much more intense,and reaches 10% in most region,even more than 30%.The basically stable area of the accumulated variation between 2009 and 2015 accounts for 30.40% of the total area in Huolinhe open-cast coalmine,Which proportion is the largest,widely distributing throughout Huolinhe open-cast coalmine.The area where vegetation coverage is degraded reaches 45.02%,and the area with contrary change of vegetation cover is 24.58%,which is significantly less than the former.There is a close relationship between the change of vegetation coverage and precipitation in the study area,and both of them have the same variation tendency.Therefore,the precipitation is the main factor in impacting of vegatation coverage change.