| Land is the material source and activity place for human beings to survive.Under the situation of rapid socio-economic development,the research on the characteristics and trends of land resource utilization is the development trend of land use research in China in recent years.Land use change,as the main driving force of ecological environment change,has an important influence on the ecological environment.As the world's most comprehensive water conservancy project,the construction of the Three Gorges Project has greatly promoted China's social and economic development.However,with the cyclical impoundment of reservoirs and the progress of urbanization in recent years,the land use structure of the Three Gorges Reservoir Area has changed significantly.A large number of cultivated land and forest land in the reservoir area have been occupied by urban land and water areas,and the surface cover has undergone tremendous changes.The ecological environment of the reservoir area has been seriously affected.This study used the Three Gorges Reservoir Area as a research area,and used remote sensing images from the reservoir areas of 2000,2004,2007,2010,2013,and 2015 as data sources,combined geographic information system(GIS),remote sensing(RS)technology,and related mathematical models to analyze the impact of land use change on the ecological environment quality after the completion of the Three Gorges Project.Findings included:(1)During the period from 2000 to 2015,the land use types in the Three Gorges Reservoir Area showed different changes.The area of cultivated land and forest land in the Three Gorges Reservoir Area were large,accounted for more than 90% of the total area of the reservoir area,they were the main land type in the reservoir area;grassland,water area,and construction land were the second largest;the area of unused land was the smallest,accounted for only 0.03% of the total area of the reservoir area.In the land use change of the reservoir area,the area of cultivated land,forest land and grassland mainly showed a decreasing trend,which was mainly attributed to changes in the population structure of the Three Gorges Reservoir Area and the large-scale occupancy of the construction of reservoirs;the area of water areas and construction land showed an increasing trend,which was mainly due to the rapid socio-economic development of the reservoir area,the impoundment of reservoirs,and the advancement of urbanization;while the area of unused land had not changed significantly during the entire study period and was scattered in the reservoir area.(2)During the period from 2000 to 2015,the overall score of ecological environment quality in the Three Gorges Reservoir Area was relatively high and tended to become better.The study selected positive indicators biological abundance index,vegetation cover index and water network density and negative index land degradation index to characterize the comprehensive index of eco-environmental quality in the Three Gorges reservoir area.The results showed that during the study period,the abundance index of the reservoir area was high,showed a slight The downward trend;the vegetation cover index was larger and more abundant;the water network density index was smaller and tended to be stable;the degree of land degradation was overall low and the change was not obvious.During the study period,the ecological environment quality of the Three Gorges Reservoir Area was generally good,and the ecological environment quality grade was above the good area with the largest area and an increasing trend.The area proportion increased from 66.41% in 2000 to 69.77% in 2015,but at the same time,there was a small amount of area had developed toward the trend of deterioration.The average value of eco-environmental quality in the reservoir area was in a good state,and its average value had increased from 60.47% in 2000 to 61.66% in 2015 and increased by 1.19% in 15 years.The results of the study showed that during the period of the study,the vegetation coverage in the Three Gorges Reservoir Area was high,the degree of land degradation was low,and the biodiversity was abundant,which was suitable for human survival.(3)The cultivated land and forest land in the Three Gorges Reservoir Area were the most important land types that contributed to the change of the eco-environmental quality in the reservoir area.The eco-environmental quality responded to the change of land use structure and the comprehensive conversion rate of land use to a certain extent.During the period from 2000 to 2015,the changes in the area of the ecological environment quality in the Three Gorges Reservoir Area were in the order of decreasing from the largest to the smallest: no significant change interval > slightly better interval > slight worse interval >obviously better interval > significantly better interval > significantly worse interval > obviously worse interval,accounted for the proportion of the total area of the reservoir area was 59.86%,26.13%,5.65%,5.09%,1.53%,1.06% and 0.69%.The types of land use change that had contributed most to the changes in the ecological environment quality in the Three Gorges Reservoir Area were mainly the decrease in the area of cultivated land and forest land,followed by the decrease in the area of grassland,while the reduction in the area of water area,the decrease in the area of construction land,and the reduction in the area of unused land also contributed to the changes in the eco-environmental quality of the reservoir area,but it was not significant.Analysis of land use structure information entropy elasticity coefficient(ERH)and land use comprehensive change elasticity coefficient(ERV)in the reservoir area.During the study period,the EHR and ERV increased by 0.2713 and 22.7184 respectively,indicated that the land use change in the reservoir area was developing in the direction of improving the quality of the ecological environment. |
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