The model provides a time series of discharge, flow area, top width, and tributary inflow at node points along a system of one-dimensional open channels. The time series of hydraulic variables can be used as input hydraulics by a transport model, such as the BLTM water quality model. The model is designed to operate with a minimum of field data. It requires no cross sectional information, the channel properties being defined by hydraulic geometry coefficients which have been found to be fairly predictable for a wide range of river sizes throughout the world. The flow must be unidirectional and backwater must not be significant, so a downstream boundary condition is not required. Model accuracy improves with river slope and model time step size. The accuracy is excellent for upland streams and it can be used can be used with good accuracy for time steps as short as one hour as long as the slope is greater than 0.0003.