A regional investigation of urban land-use change for potential landslide hazard assessment in the Three Gorges Reservoir Area, People's Republic of China: Zigui to Wanzhou

Abstract

The near-completion of the Three Gorges Dam has led to the creation of a narrow reservoir that, when completed in 2009, will stretch over 660 km upstream and result in the displacement of approximately 1.2 million people. This reservoir will drown more than 100 towns, some of which have already been lost due to the rising waters, and result in a significant change in land use. New urban areas have been constructed at higher elevations to avoid the rising water but it is feared that some of these settlements may now be exposed to a greater risk of landslides due to slope failure. A geographic information system (GIS) consisting of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Landsat Thematic Mapper (TM), and Environmental Satellite-Advanced Synthetic Aperture Radar (ENVISAT-ASAR) data has been created and used to monitor the urban changes from before the Dam's construction to the present day as well as changes in landslide susceptibility. To perform this analysis, a new 30 m high-resolution digital elevation model (DEM) was derived by combining an ASTER and Shuttle Radar Topography Mission (SRTM) DEM. Fieldwork was carried out along the Yangtze River, where the urban boundaries were field-checked using GPS to navigate to the satellite-derived checkpoints. The results show that a majority of the new urban areas are in fact located on shallow slopes, but are often positioned below steep slopes, which could pose a future threat of landslide risk to the inhabitants of the new towns.