Abstract: Since the Three Gorges Reservoir has been operated for water storage to elevation 175 m, the water levels in the reservoir area are fluctuating cyclically at the range of 30 m in the bank slope, which will lead to the changes in groundwater and reservoir banks rebuilding. And changes in groundwater and reservoir water may affect bank slope surface and rock mediums differently．It is of great significance for the disaster prevention and mitigation in the Three Gorges Reservoir area that the slope types and spatial distribution are determined. Surveying the reservoir banks in the Three Gorges Reservoir about 5311km using traditional methods, we should require a lot of human and financial resources. In this paper, with remote sensing technology, we extracted the relative sediment concentrations at the experimental zone by sediment index(SI), and graded the sediment concentration, then the spatial distributions of soil and rock bank slopes were differentiated. Comparing with the measured data, we can get a better result by the method that the bank slopes are classified by sediment concentration indirectly. The accuracy is 84.375%. This paper offers a largescale, fast, effective and new method for division of bank types.

Key words:  Three Gorges Reservoir, sediment concentration, slope type, remote sensing