Measurement-based hydrodynamic characterisation of reed – open water interface zones in shallow lake environment

Abstract

Gradient-driven interactions and exchange mechanisms of the reed - open water interface in shallow lake environment were investigated by localised field measurements and detailed data analysis. High frequency 3D flow velocities were recorded in several points throughout a typical interface zone of Lake Fertő. Based on the data the flow distribution, specific discharge, energy dissipation rate, turbulent characteristics, sediment deposition and resuspension tendencies were quantified near and inside the reed zone. Moving toward and into the reed zone, the decrease of the mean velocity component perpendicular to the interface, velocity fluctuation and the wave-related energy content of the flow were revealed along with the increasing tendency of the energy dissipation rate. Investigating the effect of different decomposition techniques on the turbulent characteristics, the one enabling the decomposition of wave-related components from turbulent components was suggested. Finally, continuous sediment deposition and the lack of resuspension were estimated in the investigated area.