Decoupling of rural population and settlement in the Three Gorges Reservoir areas in the past 40 years and its driving effect

The Three Gorges Reservoir area is characterized by ecologically sensitive, low mountains and hills in the world. The Three Gorges Reservoir area is also known as an immigration area. The rural residential lands are dominated by both natural conditions and human activities. As a result, there are special utilization form and complex driving mechanisms in this area. This study aims to reveal the functional relationship between the rural population change in the reservoir area and rural residential land evolution. From the perspective of the man-land relationship, an analysis framework was also constructed using the kernel density, Tapio decoupling model, and Logarithmic Mean Divisia Index (LMDI) method. A systematic investigation was made to determine the decoupling and driving factors of the rural population and rural residential land evolution from 1980 to 2019. The results show that: 1) There was the opposite change trend of the rural population and rural residential land. The rural population continued to decrease, with a net decrease of 7 147 500 people over the past 40 years. By contrast, the rural residential land increased by 11 992.88 hm2 during the same period. The ever-increasing areas of rural residential land mainly originated from the occupation of cultivated land by construction land. 2) The negative and strong negative decoupling from recession were the main dynamic changes in rural settlements and rural populations in the study area. The number of counties with a strong negative decoupling of the rural population and rural settlements in 1990-2000 and 2000-2010 was more than that in 2010-2019 and 1980-1990. The scale of rural residential land was accompanied by a decrease in the rural population. There was an outstanding trend of increasing rather than decreasing. A serious unbalance was also found in the scale of the rural population and rural residential areas. 3) There was the incremental effect of urbanization and utilization intensity, indicating the positive promotion in the scale expansion of rural residential areas. The urban-rural population structure was the dominant factor to inhibit the scale expansion of rural residential areas. The regional total population promoted the expansion of rural residential areas from 1980 to 1985 and from 2000 to 2019. Nevertheless, the expansion of rural residential areas was inhibited from 1985 to 2000. Therefore, the scale expansion of rural residential areas depended mainly on the intensive and extensive use of rural residential areas. The regions and counties with the decreasing effect of the regional total population were located mainly in the central and eastern regions. It infers that there was a significant influence of the population outflow caused by the migration from the reservoir area. The finding can provide the basic ideas to coordinate the man-land relationship for the better management of territorial space.