Research On Dynamic Change Of Vegetation Coverage In The Traffic Corridor Based On ERDAS

The study area in the thesis is located on Otindag Sandy land, which has severe degradation of vegetation with the changes of modern climate and human activity. Transportation is an important part of the national economy, the desertification of the land caused by vegetation degradation is closely related to the security of transportation operation.Therefore,quantitative analysis of transport infrastructure on vegetation demage and recovery is important. The paper studies quantitatively the spatial and temporal distribution together with the laws of dynamic change on vegetation coverage within the traffic corridor on Otindag Sandy land, and it analyses that the transportation infrastructure have effcts on vegetation destruction and recovery. Vegetation coverage is direct indicating factor of vegetation, and NDVI (normalized difference vegetation index) is a widely used vegetation index, they compose an organic link in the dimidiate pixels model by ERDAS software. The spectral information of remote sensing is converted to vegetation coverage by NDVI.The result of the study shows that the water area in traffic corridor over the past 35 years reduces continuously. The vegetation went through a period of slow degradation from 1975 to 2000,a reversal phase from 2000 to 2006 and a rapid degradation period from 2006 to 2009.The area of low coverage of vegetation increased continuously from 1975 to 2005, the average annual growth rate at 2.0%-9.2%, its area decreased by 42.5% in 2006, from then on it increased rapidly, the average annual growth rate was 4.5%-25.2%. The ratio of area from midium coverage of vegetation in total assessment area had always been 22.2%-27.2%. it had dramatic change in some years. The area of high coverage of vegetation took on a descenting trend on the whole in 35 years, it had dramatic fluctuation from 2004 to 2007. Water area also reduced continually, the area that was 218 hm2 in 1975 down to 69 hm2 in 2009.The railway shelterbelt integrates with high coverage of vegetation witnin traffic corridor on Otindag Sandy land, it has obviously segmentation for the low coverage of vegetation,and it owns strong capability to resist vegetation degradation. The protective effect of railway shelterbelt is better than the road.Highway construction damages ground vegetation seriously, especially the temporary land and large slope zone. When it had been cultivated and maintained in several years, the highway shelterbelt has obvious effect on protecting highway infrastructure and preventing desertification from surface.