Dynamic Change Of Vegetation Coverage And Driving Factor Analysis Based On Landsat Hefei

With the rapid development of urbanization in Hefei,the ecological and environmental problems continue to emerge,and the fractional vegetation coverage(FVC)is an important indicator to describe the changes of regional ecological environment.It is of great significance to study the vegetation coverage and its spatiotemporal variation law for analyzing the changes of regional ecological environment.It is of great theoretical significance and practical value to quickly and accurately grasp the dynamic variation characteristics of vegetation coverage for urban sustainable development and mining the regional surface vegetation distribution law.In this paper,the linear spectral mixture model,pixel dichotomy and improved three band gradient difference model are used to invert the vegetation coverage in the study area.The results show that the inversion correlation coefficients of the three models are 0.875,0.751 and 0.86 respectively.The correlation of the inversion accuracy of the three models is high,but the pixel dichotomy model has the highest inversion accuracy,which indicates that the pixel dichotomy model has the highest inversion accuracy The dichotomy model can better reflect the real vegetation cover.The vegetation cover of Hefei city is taken as the research object,and the results are based on Landsat Based on TM / ETM / oli remote sensing image data,the temporal and spatial distribution characteristics of vegetation coverage from 2008 to 2019 were studied.The change characteristics of vegetation coverage in Hefei city were quantitatively and qualitatively analyzed by Hurst index,trend analysis method,difference image algorithm and Markov transfer matrix,and the future change trend of vegetation coverage in Hefei city was predicted.At the same time,combined with meteorological factors,terrain factors and social and economic activity factors,the response characteristics of vegetation coverage were explored.The results show that:(1)The overall situation of vegetation coverage in Hefei is good.Meanwhile,the overall spatial distribution of vegetation coverage has a strong spatial correlation with the main urban area.The overall spatial distribution is high in the South and low in the north,and the high coverage areas are mainly distributed in the southwest and northeast of the main urban area,while the central and Chaohu urban areas are mainly low and low.On the interannual change,the average vegetation coverage in the study area showed a fluctuating upward trend,but the upward trend was slow.(2)The change characteristics of Hefei's vegetation coverage are generally positive.The vegetation coverage in the periphery of the main urban area has a certain downward trend.From 2008 to 2013,the change trend of Hefei's vegetation coverage is mainly degraded.The overall vegetation coverage from 2013 to 2019 Shows an improvement trend.In addition,the vegetation coverage areas of various levels are frequently transformed,and there is a tendency for high coverage areas to degenerate into higher coverage areas.The future trend of vegetation coverage in Hefei is expected to be mainly improved.Among them,the main urban area is expected to improve significantly in the future vegetation coverage,while the outer area of the main urban area is expected to be mainly reduced,indicating that in the face of the general trend of urban economic development,while improving urban greening,attention should be paid to protecting urban expansion.For environmental issues that come,pay attention to the environmental protection and governance of degraded vegetation coverage areas..(3)The response characteristics of the influencing factors of vegetation coverage in Hefei indicate that socio-economic factors are the main factors in the evolution of vegetation coverage in Hefei.The contribution rates of various influencing factors are GDP,permanent population,annual average temperature,and annual precipitation in order.Among them,the climate evolution of Hefei City generally has a trend of "warming and drying",and the annual average temperature has a lower degree of vegetation coverage with a higher degree of negative correlation;Hefei City has a slower altitude,mainly distributed in Level I and II Grade-level elevation zone,in the flat slope area,the average vegetation coverage is the lowest,and the vegetation coverage has the characteristics of improving with the elevation.At the same time,except for the shaded slopes,the area of each grade in the study area is basically the same.Among them,the vegetation coverage of shaded slopes is higher than that of other grades.Incoming vegetation coverage has less impact.