EP51C-0928
Experimental Study on the Characteristics of Scour Hole around Emergent Vegetation with Single-Density

Friday, 18 December 2015
Poster Hall (Moscone South)
Chen Chieh Peng, National Chung Hsing University, Taichung, Taiwan
Abstract:
In the natural rivers, woody vegetation commonly grows along the riverbank. When flows run through the woody vegetation zones, the stream processes and bed form are markedly affected. This study aimed to investigate the characteristics of scour hole around vegetation patch with different densities by flume experiments. For corresponding to the natural plant growing condition, the vegetation models were arranged along one side of the flume wall. The vegetation models were made of the steel columns with staggered arrangement. The vegetation densities were set equal to 0.03, 0.04, 0.05, 0.07, 0.09, 0.12, 0.15, 0.22 and 0.3. The experimental flow condition was steady and the vegetation models were emergent. The flow velocity was controlled close to the initiation of sediment motion. The scour patterns around the vegetation zone were measured by the Laser Distance Meter in equilibrium scour conditions. The results show that the scour patterns have similarity in vegetation density ranging from 0.03 to 0.12. The dimensionless scour length (D) is ranging 1.30-1.50. The dimensionless scour width (B) is ranging 1.11-1.48. The dimensionless accumulation width (E) is ranging 1.18-1.67. The dimensionless accumulation length (F) is ranging 0.49-1.81.The results also show that B and E are proportional to the vegetation densities, and the D and F are inversely proportional to the vegetation densities.