Flow characteristics in vegetated compound channels

Turbulence measurements were carried out in compound channels with roughened floodplain. Mean flows are described through turbulence and secondary currents are explored through vorticity analysis. Turbulent intensities, turbulent kinetic energy and Reynolds shear stress are presented. Energy spectra are related to reveal the contribution of large horizontal eddies to the momentum exchange. Secondary currents influence velocity patterns in compound channels with and without vegetation. The secondary currents are stronger in the vegetated compound channel than in non-vegetated one under similar water depths. From results of vorticity analysis, an anisotropic turbulence is the main contribution to generation of secondary currents in both cases, but the Reynolds stress term is more important in the vegetated compound channel since vegetation generates wake turbulence rather than free shear turbulence. This is supported by the result of spectrum analysis.