Evaluation Of Highway Ecological Environment Impact In Tibet Based On Remote Sensing Index

Tibet as a important ecological security barrier region in China and constitute important part of the national“Two Screens and Three Belts”ecological security pattern.The area of the protected area alone accounts for one third of the total area of Tibet,and its ecological position is very important.The construction of road traffic is a necessary factor for accelerating the economic and social development of Tibet.After more than 20 years of development,the level of highways at all levels in Tibet has been increasing year after year,which has gradually improved the traffic conditions that restrict the economic development in Tibet.However,the bearing capacity of resources and the environment in Tibet is extremely limited,the ecological sensitivity is strong,and transportation construction cross ecological protection zones inevitably.Therefore,coordinating the relationship between transportation construction and the ecological environment in Tibet is the only way to develop the economy in Tibet.It is particularly important to analyze and evaluate the impact of road construction projects before and after construction.Lalin dual carriageway as the first real highway in Tibet,is an important channel that runs through eastern Tibet and central Tibet.Our country has invested nearly 400 million yuan for ecological recovery during the highway construction process,which shows that The country attaches great importance to environmental protection.In this paper,the research area of 5km on both sides of the highway from Nyingchi to Gongbujiangda County in Lalin dual carriageway is used as a research area to carry out the ecological environment quality and impact assessment research of the road area,and to provide a reference for the Tibet highway ecological environment assessment research in the future.This paper based on other research and analysis from other researchers,selects FVC,LAI,GPP,LST and Wet as evaluation index according to the unique geographical environment of Tibet,and uses MODIS product data as the data source to calculate and extract the remote sensing index on the analysis platform of ArcGIS,ENVI and Google Earth Engine,Using the Principal Component Analysis(PCA)to construct an ecological comprehensive index model to evaluate and analyze the ecological environment quality of the research area;Finally,build an ecological information prototype system based on WebGL technology and B / S architecture to realize the browsing and storage of ecological information data,etc.The function of data management to improve the effectiveness and feasibility of ecological informationization in Tibet is of great significance for coordinating transportation construction and ecological environmental protection in Tibet.The following research results were obtained:(1)Green index,Thermal index and Wet index could better reflect the local ecological environment in Tibet.Green factor and Wet factor have a positive effect on the quality of the ecological environment in the research area,and Thermal factor has a negative effect.(2)The overall ecological quality of the area along the Nyingchi to Gongbujiangda County in Lalin dual carriageway in 2019 is better than in 2012.Compared with 2012,the ecological comprehensive index increased by 4.22% in 2019,but the ecological comprehensive index in the research area fluctuated greatly during construction and after it was put into use.The period from 2013 to 2015 was the construction period,during which the ecological comprehensive index decreased first.The post-increasing change trend is mainly due to the damage to the ecological environment and the implementation of ecological restoration work;2015 to 2019 is the highway use period.During this period,the ecological comprehensive index showed a downward trend and then increased.This is due to The high local ecological sensitivity has caused the ecological restoration effect to rebound.(3)Compared with the construction of the section in Nyingchi to Gongbujiangda County of the Lalin dual carriageway before construction and after being put into use,the local ecological quality change level is mainly unchanged,and the area with constant ecological quality accounts for 66.045% of the total.In the change of the ecological quality level after the construction of the highway,the area of the ecologically improved area is slightly larger than the ecologically degraded area.The areas with the improved ecological quality mainly include the conversion from the original poor level to the general level and the original general level to the good level.,The ecological quality degradation area is mainly converted from the original good level to the general level.