Author(s): Anna Chiara Bixio
Linked Author(s):
Keywords: Flow resistance; Emergent vegetation; Experimental measurements
Abstract: Due to its efficacy in phytoremediation processes, reed-type vegetation has been widely used in constructed wetlands for water quality improvement and in river restoration projects. However its application has been based on experience rather than hydraulic principle, and limited knowledge exists concerning the hydraulic resistance properties of reed beds. Experimental studies are needed to quantify vegetative flow resistance, in order to improve the mathematical representation of the physical processes that influence flow resistance and also to assess the values of associated parameters in numerical models of surface-water flow, which are widely used for wetland design and management. This paper presents the first results of the experimental measurements performed during summer 2006 in a reed-vegetated flume located inside the Monselice wetland, in northern Italy. The flume was appositely built up for experiments preserving undisturbed the natural local vegetation, mainly consisting in Phragmites australis plants. A differential piezometer system was used to evaluate energy losses along the flume. Experiments were conducted for four different flow depths varying between about 0. 30 and 0. 60 m and three flow rates between 20 and 30 l/s. The Manning’s n coefficient, commonly used to express flow resistance in open channels, was computed from measured flow rate, water depth and water surface slope data.
Year: 2007