Authors: SUN Xiao-li *, WANG Jian-yue *, Allen Thompson **

* China Institute of Water Resources and Hydropower Research, Beijing 100048, China
** China University of Missouri-Columbia, Columbia Mo 65201, USA

Abstract: Based on annulus flow, modification was made to the turbulent flow term in the Ergun equation to account for flow resistance of plant roots in submerged flow rock beds. For four-year plant growth measured hydraulic data using two rock media in the flumes 7.62m x 0.46m x 0.31m and 7.62m x 0.46m x 0.295m were compared with the predicted results using the Ergun and M-E equations. Differences of root distribution in vertical direction resulted in two distinct root profiles, with the upper portion of the bed having a greater porosity reduction. The Ergun equation greatly underestimated the head loss of the rock media beds. It is concluded that the head losses modeled by the equation (M-E-pl) are close to the measured data of the peal gravel rock bed, if plant root effect is considered, but it is slightly underestimated head loss for the lower portion of the bed for the creek rock bed.

Key words: annulus flow, plant root, rock bed, head loss, porosity

Published in: Journal of Hydraulic Engineering, Vol. 42, No. 8, 2011
Article ID: 0559-9350 (2011) 08-0934-07