Changes in cultivated land patterns and driving forces in the Three Gorges Reservoir area, China, from 1992 to 2015

Changes of cultivated land patterns caused by major water conservation projects are rarely reported. We selected the Three Gorges Reservoir area in China to study the change in area and landscape pattern of the cultivated land in the head, central, and tail areas of the reservoir that took place between 1992 and 2015; we then studied the spatial distribution of the cultivated land in the three parts of the reservoir; finally, we studied the driving forces behind the changes in the cultivated land. The results derived are as follows. (1) During the construction of the Three Gorges Project (TGP, 1992-2015), the area of cultivated land around the reservoir decreased by 30.23 million ha. This reduction occurred in phases: the most severe change in cultivated land occurred during the later stage of the project (2002-2010); only 0.62 million ha of cultivated land did not change between 1992 and 2015. (2) Spatial pattern analysis showed that the cultivated land in the three parts of the reservoir changed from a northern distribution to a southern distribution; thus, the area of cultivated land in the north decreased over the time period. The area of cultivated land in the head and tail areas decreased by varying degrees, while it increased in the central area over the 23 years, indicating that the change in cultivated land showed regional differences. (3) The TGP, the policy of reverting farmland to forest, and urbanization were the main driving factors for the change of cultivated land, but there were differences in their impacts at different stages. (4) According to the patch dynamics of the land cover change, the degree of change gradually intensified during the early and later stages of the project and then stabilized during the operational period. Our research provides scientific support for the protection of cultivated land resources and food security in the reservoir area and for the coordination of social and economic development, which is of great significance to sustainable development in the reservoir area.