Turbulent kinetic energy of water in a compound channel

Abstract

Turbulent kinetic energy of water in a compound channel. The aim of the experimental research was the determination of water turbulent kinetic energy changes in a compound channel without and with rigid, emergent, vegetation existing on fl oodplains. Two tests for two various roughness of fl oodplains were realized. In the fi rst test the surface of the main channel bed was smooth and made of concrete whereas the fl oodplains and sloping banks were covered by cement mortar composed with terrazzo. In the second test the covering of the fl oodplains was left as in the fi rst test but additionally emergent vegetation (trees) growing on the fl oodplains were modeled by aluminium pipes. Instantaneous velocities were measured with use of a three-component acoustic Doppler velocity meter (ADV). The infl uence of trees, located on fl oodplains, on the distributions of turbulent kinetic energy in the main channel and on the fl oodplains were presented. The distributions of turbulent kinetic energy at different water depths were described by regression equations. Vertical distributions of turbulent kinetic energy on the fl oodplains and over the banks of the main channel were divided into three zones. Over the bottom of the main channel, four zones were determined, containing the middle zone of the fl ow fi eld divided into two zones of different trends.