Land use change and causes in the Xiangxi catchment, Three Gorges Area derived from multispectral data

The construction of the Three Gorges Dam on the Yangtze River has extensive impact on the ecosystems and the population of the Three Gorges Area (TGA). Inundation and resettlement have induced far-reaching land use and land cover change (LUCC). The areas that are affected by measures of resettlement are in a tense situation between the implementation of various governmental tasks addressing sustainable land use and water retention and the fulfilment of the population’s economic needs, which primarily depend on agricultural production. Destabilization of slopes and soil erosion are immediate hazards induced by the impoundment. Farming is a very important source of income and has to persist on the one hand to assure the income of the rural population. On the other hand, the environment has to be protected from runoff, soil erosion and instabilities connected to relief, geology and hydraulic influences. In this study, supervised classifications are performed using Landsat-TM (1987 and 2007) and ASTER (2007) images. LUCC is assessed by post-classification change analysis. On the catchment scale, arable land has decreased significantly, while garden land (citrus orchards) and woodland have increased. LUCC mainly affects the area surrounding the reservoir (“backwater”) of the Xiangxi (香溪) River, driven by local resettlement, newly built infrastructure, relocation of land cultivation, and conversion of arable land to garden land. In the hinterland, LUCC occurs in form of abandonment of land cultivation as a consequence of the Grain-for-Green programme.