A computer code, BCS, was developed to simulate the three-dimensional topographical expression of braided channel systems. The model uses a random walk approach to simulate channel braiding and incorporates the hydraulic geometry of stream channels to assign width, depth, and velocity to each channel segment. Input parameters are directly related to observable geometric characteristics of a braided system such as channel system width, depth, and sinuosity. Thirty-one measures of the degree or type of braiding were taken from the literature and used as calibration targets for the model. All targets were matched for a portion of the Ohau River, New Zealand. This simulation technique can be used to assess quantitatively the distribution of channels with their associated hydraulic properties and visualize topographic surfaces associated with braided channel systems. This information provides a foundation for probabilistic (multiple realizations), geometric simulation of the three-dimensional distribution of braided stream sediments. ¿ American Geophysical Union 1995.