Vegetation Changes Around Alberta Oil Sands,Canada,Based On Remote Sensing Data In 1995?2020

There are a lot of oil and gas resources in Alberta oil sand mining area in Canada,Therefore,since the 1960 s,the Canadian government has decided to increase the mining intensity of the area to meet the needs of development.However,the development and exploitation of oil sand mining area will inevitably bring many adverse effects on the surrounding ecological environment.In recent years,people pay more and more attention to the environmental protection and ecological restoration of the oil sand mining area and its surrounding areas.The change of vegetation area and vegetation index is an important symbol of evaluating the environment.It can effectively measure the surface vegetation status,so as to analyze the vegetation status,and then make environmental impact assessment on the region and formulate reasonable treatment scheme.Vegetation index has been widely used in various fields of environmental monitoring.In this study,USGS landsat5 TM and remote landsat-8 OLI/TIRS sensing images were used as the basic data sources.From 1995 to 2020,Alberta oil sand mining area and its surrounding 4687 square kilometers are selected as our research area.After pretreatment of radiometric calibration,atmospheric correction and geometric correction,the land cover classification maps of 1995,2000,2005,2010,2015 and 2020 were obtained by visual interpretation with ENVI software.Then,three vegetation index maps(NDVI,NDMI and RVI)of the study area in each period are processed and output by ENVI software to explore the long-term impact of the development and mining of the oil sand mining area on the vegetation in the mining area and its surrounding areas.According to the main research content of this paper,the following research results and understanding are obtained:(1)From 1995 to 2000 and 2015 to 2020,the proportion of vegetation around the oil sand mining area changed little;from 2000 to 2015,the peak period of oil sand mining development,a large amount of vegetation in the study area was removed,and the proportion of vegetation decreased rapidly.The proportion of vegetation in the study area showed a downward trend;the proportion of sand washing pool,oil sand mine and other land in the mining area showed an upward trend;the proportion of water body fluctuated up and down.Especially in 2000?2015,this change is particularly obvious.During the period of 2015?2020,the development of oil sand mining area is basically completed,and the change of vegetation proportion in the study area is very small.From 1995 to 2020,only vegetation will be reduced in the study area,and the original vegetation land will be converted to sand washing pond,oil sand mine and other land types in the mining area.(2)Comparing and analyzing the three vegetation indices(NDVI,NDMI and RVI)in each period,it is concluded that with the development and exploitation of oil sand mining area in Northern Alberta from 1995 to 2020,the three vegetation indices(NDVI,NDMI and RVI)show a downward trend;2000?2010 is the most rapid stage of oil sand mining development,and the corresponding vegetation index is also the fastest decline,especially the vegetation index RVI;From 1995 to 2005,the decrease of NDMI was much faster than that of NDVI,indicating that the development and exploitation of mining area had a significant impact on vegetation water body,the change trend of NDVI and RVI was very similar,and NDMI decreased significantly from 1995 to 2010,and tended to be stable from 2010 to 2020.The results show that the vegetation coverage decreased in the early stage of mining from 1995 to 2010,while the vegetation water body also decreased rapidly;after 2010,with the gradual improvement of mining area development,the decline of vegetation coverage slowed down,and the change of vegetation water body index tended to be stable.(3)From around 2015,due to the policies of the Canadian government and the joint efforts of some environmental protection organizations,The development progress of Alberta oil sand mining area is slowing down,and most of them are mining in the original mining area.While mining the original oil sand mine,the restoration of surface vegetation is also gradually carried out.