Artificial emergent vegetation can increase flow resistance and water depth to improve navigation in an open channel. An innovative and eco-friendly artificial vegetation system is analyzed in this study. First, a new method is presented to modify the depth-averaged Navier–Stokes equation by incorporating the vegetation drag force term. Two analytical formulas based on theoretical analysis are proposed to predict the lateral distribution of depth-averaged velocity in an open channel with fully and partially artificial vegetation. Then, the analytical formulas are verified by laboratory experiments. The results of the analytical model are consistent with experimental data, thereby proving that the analytical formulas can be used to predict the lateral distribution of streamwise velocity in open-channel flow with artificial emergent vegetation. The presented model can provide a significant theoretical reference for research on open channels with artificial emergent vegetation.