Spatial relationships between surface sediment distribution and channel networks were estimated for the Ganghwa-Do southern tidal flat, Korea. Tidal channels were extracted from high spatial resolution satellite data and used to derive maps of channel density and distance from channels. The map of surface sediment distribution was produced from grain-size data on sediment samples. Then, for each surface sedimentary facies, the relations with tidal channels were estimated in terms of the fractal analysis, channel density and distance from the channel. The results demonstrate a significant spatial relationship between the distribution of surface sediment in a tidal flat and tidal channel distibution. We conclude that tidal channel should be considered an important factor in mapping surface sedimentary facies in tidal flat environments, and that patterns of tidal channel are a useful adjunct to spectral reflectance in classifying the surface sediment from remotely sensed data with high spatial resolution.