Hydraulic Features of Flow through Emergent Bending Aquatic Vegetation in the Riparian Zone

Water

Jihong Xia¹ 

[1]College of Water Conservancy and Hydropower, Hohai University, 1 Xikang Road, Nanjing 210098, Jiangsu, China

关键词: riparian zone;    flexible aquatic vegetation;    ecohydraulics;    Manning coefficient n;    vertical velocity;    turbulence;   

DOI  :  10.3390/w5042080

来源: mdpi

【 摘 要 】

Vegetation in riparian zones has a significant influence on resistance, velocity distribution and turbulence intensity. This study experimentally investigated the effect of emergent bending riparian zone vegetation on the flow. The results showed that the frond and stem parts of Acorus calami had different influences on hydraulic features and that the relative depth ratio of water depth h to stem height h_s was a key determinant of those influences. Manning coefficient n varied greatly with the variation of vegetation densities, relative depth ratio of water depth h to stem height h_s, Re and Fr. Manning coefficient n increased with increasing vegetation density, particularly in cases when h/h_s > 1. The velocity distributions did not follow logarithmic profiles, but they instead exhibited double logarithmic profiles. In addition, vegetation characteristics were shown to influence the height of maximum velocity. The position of maximum velocity is further away from the bed in cases with denser vegetation distribution. Finally, turbulence intensity showed more significant variation in the stem part and peaked near the middle of the stem, at z/h_s = 0.5, where z was the distance from the bottom.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.