Author(s): Jiahao Zhang; Mengzhen Xu; Wei Liu; Tongyu Zhang
Keywords: Mussel attachment; Biofouling; Water conveyance efficiency; Roughness; Feeding behavior
Abstract: Interbasin water transfer projects are widely used to alleviate the uneven distribution of water resource. However, some of them are facing the risk of mussel invasion and attachment, e. g. the prevalent problems caused by the golden mussel biofouling in water transfer facilities in Asia and South America, and the zebra mussel fouling on hydraulic structures in North America. Mussels attach to the inside surfaces of pipelines with high density, forming clusters and layers, causing serious biofouling, and affecting the pipe-wall roughness and thus reducing water conveyance efficiency. An experimental pipeline system was designed and applied to study the effect of the golden mussel attachment on the roughness of water transfer pipeline. Mussel substrata were created by collecting bamboos attached with the golden mussels in the Xizhijiang River in South China. The mussel attachment densities of the substrata were manually set to different levels varying from 0 to more than 12000 individuals per square meter. Flow field was measured using a Vectrino Acoustic Doppler Velocimeter (ADV, manufactured by Nortek, Norway, sampling frequency: 200Hz) under the conditions of the different attachment densities. Then Manning’s roughness coefficient n was calculated for the different conditions based on hydraulic radius segmentation. It was found that the n-value increased with the mussel attachment density increasing, and the n-value for the highest attachment density was about twice higher than the one without mussel attachment. In addition, the mussels’feeding and breathing activities by taking water in and out through their body examined and showed negligible to affect the roughness.