The numerical simulation of 3-D seepage flow for Gong-Bo-Xia Hydropower Project is described in this paper. Gong-Bo-Xia Hydropower Project is a large multipurpose hydropower project, with total capacity of 1500MW, in Yellow River, it is located in Qinghai Province, China, and composed of outlet works, dam, intake of hydropower system, low-level outlet and concrete cutoff etc.. The physical seepage space is very large. Its boundaries are such that the upstream boundary is taken at 480m upstream from axis of dam; the downstream one is taken at 900m downstream from axis of dam; the lowest bottom boundary is taken at elev.1800m the left boundary is taken at 200m outside of the left wall of the spillway and the right one is taken at 100m outside the right end of the concrete cutoff. Considering the complexity of the layout of the project and the seepage space, as well as the variety of the seepage control measures, Boundary-Fitted Curvilinear Coordinates (BFCC) transformation and domain decomposition technique has been used here to perform the numerical simulation of 3-D seepage flow of several alternatives. According to the results and analysis, some conclusions were made, which provide a useful basis for the project design with reliable safety and economy.
