Author(s): D. S. Rhee; D. H. Lee; C. W. Kim
Linked Author(s): Dong Sop Rhee
Keywords: No Keywords
Abstract: Riparian vegetation is one of the important factors for improving and restoring river environments. It adds high aesthetic values to regulated rivers. Also, it can be used as a levee protection or revetment in an environment-friendly way. However, in open channel hydraulics, vegetation in the river usually causes changes in flow resistance and thus induces the water level to increase. Because the increasing of water level is a very serious problem in river restoring works, several researches have been conducted on the flow resistance of riparian vegetation experimentally and numerically. Although those researches make a remarkable advancement, it is very difficult to adapt these results to other region because of a locality problem. Each research is often limited on the local vegetation. Therefore, it is possible that those target species of vegetation are very rare and not found in other regions sometimes, especially in Korean rivers. Some Korean natural plants like Zoysia matrella (Korean Golden Zoysia), Pennisetum alopecuroides (L.) Spreng. (Korean Pennisetum), and Phragmites communis Trin. (Reed) were tested to find the values of hydraulic resistance in a former study (Rhee et al., 2008). These three vegetation maybe were treated as the representatives of Korean riparian vegetation, however, the linkage of other Korean natural vegetation is not identified yet. As a preliminary research, the hydraulic resistance of other Korean natural vegetation like Phragmites japonica Steud. (this plant is very similar to reeds in shape) is investigated to find the linkage and similarity between tested vegetation and reed in this study. Target vegetation was unmown and tested under both submerged and un-submerged conditions. Resistance coefficients, expressed as Manning's n, of Phragmites japonica Steud. are higher than Phragmites communis Trin., based on developed ‘n-VR'retardance curve. This is because the abundance of leaf elements and the growth stages of the vegetation. It means that, though the flow resistance is largely determined by the type and characteristics of vegetation, seasonal effects affect vegetation growth are also considered to estimate the flow resistance of the river.
Year: 2009