A two-layer approach for depth-limited open-channel flows with submerged vegetation

Abstract

A two-layer approach for depth-limited open-channel flow with submerged vegetation is described. A momentum balance is applied to each layer and expressions for the mean velocities are proposed. The velocity is assumed to be uniform in the vegetation layer and logarithmic in the upper layer. The proposed relationship successfully predicts the mean velocity distribution when compared with the measured data. Using the velocity formula, the layer-averaged mean velocities in the upper layer and over the entire layer are derived. An expression for the roughness coefficient increased by vegetation is also presented, performing better for the roughness coefficient than other formulas. Another relationship is proposed for predicting the distribution of suspended sediment in depth-limited flow with submerged vegetation by using an eddy-viscosity profile. The predicted profiles moderately agree with the measured data. Comparisons with simulated data from the Reynolds-averaged Navier–Stokes equations with the k–ϵ model suggest that these proposals successfully predict suspended sediment transport in a depth-limited flow with submerged vegetation.