| As one of the five largest freshwater lakes in China,Chaohu has always received widespread attention.With the rise of a large number of industrial and modern construction facilities,the acceleration of urbanization and the impact of human activities,the land use structure and ecological environment in the region have undergone tremendous changes.Since Chaohu was included in Hefei City in 2011,Hefei has increased pollution and environmental remediation around the Chaohu Lake Basin,strengthened industrial pollution supervision,reduced agricultural non-point source pollution,and vigorously restored river and lake wetlands.In order to understand the changes in land use structure and vegetation restoration in this area,this paper takes the area around Chaohu Lake(including the water surface of Chaohu Lake and the surrounding Feidong County,Feixi County,Baohe District,Chaohu City and Lujiang County)as the research area.The remote sensing image data and the MODIS NDVI long-term sequence data from 2009 to 2018 in the fourth period of 2012,2015,2018 and 2018 were used as data sources.The software MRT,ENVI,Arc GIS and other software were used as data processing and analysis platforms to analyze the environment in detail.Spatiotemporal dynamic changes of land use in Chaohu area and spatiotemporal changes of vegetation index and their driving factors.Provide a scientific basis for objectively evaluating the environmental improvement effect and land planning adjustment in the area around the Chaohu Lake.The main results are as follows:(1)From 2009 to 2018,the land use types around the Chaohu Lake area were mainly cultivated land,forest land and water area.In the past 10 years,the area of cultivated land in the Chaohu Lake area has been shrinking,accompanied by a large-scale expansion of forest land and construction land and a small increase in water area.Among them,the change in forest land area was the most obvious from 2012 to 2015.?2012-2016 Anhui Province Ten Thousand-Mu Forest Growth Project ?based on the analysis of the transfer matrix in 4 periods,it was found that the conversion of land use types in the Chaohu Lake area mainly flows between cultivated land,forest land and grassland.The dynamic change of single land use in the area around Chaohu Lake has obvious changes from 2012 to 2015,and the circulation between land use types is more violent,reflecting the rapid development of the social economy in the area around Chaohu Lake from 2012 to 2015;Cultivated land area,forest land area,construction land area and grassland area changed significantly;water areas and unused land changed little.(2)In terms of time,the vegetation growth in the area around Chaohu Lake has been in good condition for 10 years,and the normalized vegetation index(NDVI)has increased significantly,which is also consistent with the timeliness of Chaohu 's policy of returning farmland to forest since 2002.From a spatial point of view,the NDVI value of mountain vegetation in the Chaohu Lake area is high,and the average value of NDVI in the southern part of the study area is higher than that in the northern part.Judging from the seasonal average NDVI distribution map,the spatial distribution of NDVI values in the four seasons around the Chaohu Lake area shows that the average value of the southern part of Chaohu Lake is greater than that of the northern part,and the mountain vegetation coverage is the largest.From 2009 to 2018,the vegetation NDVI value increased significantly.The contribution rate of forest land was the largest,and the vegetation in the area around the Chaohu Lake showed an overall improvement.(3)The study found that the annual inter-annual change of vegetation NDVI in the area around Lake Chaohu did not respond significantly to the temperature and precipitation,but it responded significantly to changes in monthly temperature and precipitation.Elevation and slope also have a certain degree of influence on the NDVI situation around the Chaohu Lake area. |
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