Author(s): E. P. Kostidou; G. C. Christodoulou
Linked Author(s): George Christodoulou
Keywords: Flow through vegetation; Flow resistance; Equivalent sand roughness; Environmental hydraulics; Ecohydraulics
Abstract: The paper focuses on determining the resistance characteristics of some selected artificial vegetation elements and patterns in terms of the friction factor f and the equivalent sand roughness ks, based on laboratory experiments. Three types of vegetation elements were used: (a) Thin rigid rods 0. 5 cm in diameter and 4 cm high, always submerged; (b) Flexible plastic tubes (20 cm high) adjusted on the same rods, which were submerged or emergent depending on the flow rate; (c) Compound elements, consisting of rigid rods 0. 8 cm in diameter and 5 cm high, bearing 3 cm diameter spheres on top, mostly submerged. Three patterns of each type of element were investigated, at plan densities ranging from 100 to 400 stems/m2. By measuring the free surface profiles, the Manning’s ncoefficient was evaluated and subsequently the respective friction factor f and equivalent roughness ks were determined. The results are corrected for sidewall effects and presented in dimensionless form. Quantitative expressions are proposed relating f and ks to the density and other geometrical parameters characteristic of the vegetation array. Comparison with previous research is discussed.
Year: 2015