Spatio-temporal evolution of ecological environment quality in the Three Gorges Reservoir Area: from the perspective of synergistic effects of natural and human activities

The Three Gorges Reservoir Area is an important human activity area in the hinterland of China. There are many cities and major water conservancy projects in the area, and it is also an ecologically fragile area, which is highly sensitive to the complex terrain and the impact of the Three Gorges reservoir. As the key focus of the national regional development policy, the region involves a number of regional development strategic plans, such as the great protection of the Yangtze River, the construction of the Yangtze River economic belt, the rise strategy of central China, the conversion of farmland to forests, and resettlement. Therefore, its ecological environment quality and protection measures are highly valued by the state. However, the previous related research institutes still have the following shortcomings: First, the time series data time resolution is low. Secondly, the research methods And methods are not close enough to the regional geographical And human characteristics, which reduce the adaptability of the research results to a certain extent. In view of the above shortcomings, this study uses time series harmonic analysis algorithm to optimize image data based on Landsat remote Sensing images from 2000 to 2020 and Google Earth engine platform. Based on the traditional RSEI, the normalized water index and soil regulation vegetation index were added to build an improved remote sensing ecological index SRSEI for TGRA, which can effectively improve the ability of water identification and monitoring of sparse vegetation areas. Sen slope estimation and Mann–Kendall test were used to Analyze the spatio-temporal variation trend of SRSEI, And the driving mechanism of land use, elevation, climate, social economy, and other factors was explored by using geographic detector model. Get more reliable evaluation results and impact factors. The results show that the average SRSEI of TGRA from 2000 to 2020 is 0.529, And the overall ecological environment quality is at the upper middle level, And the area with slight improvement after 2010 accounts for more than 50%, showing a good trend as a whole. Single factor driving Analysis showed that land use And elevation were the dominant factors affecting the quality of ecological environment; The interaction showed that the synergistic effect of land use and other factors further magnified its impact on ecological quality. In conclusion, human activities may be the main reason for the change of ecological environment quality in the Three Gorges Reservoir Area in the past 20 years. This study can provide a scientific basis for the formulation and implementation of ecological and environmental protection policies in TGRA.