title: Biostabilization and Transport of Cohesive Sediment Deposits in the Three Gorges Reservoir.
abstract: Cohesive sediment deposits in the Three Gorges Reservoir, China, were used to investigate physical and geochemical properties, biofilm mass, and erosion and deposition characteristics. Biofilm cultivation was performed in a recirculating flume for three different periods (5, 10 and 15 days) under ambient temperature and with sufficient nutrients supply. Three groups of size-fractionated sediment were sequentially used, including 0-0.02 mm, 0.02-0.05 mm and 0.05-0.10 mm. Desired conditions for erosion and deposition were designed by managing high bed shear stress at the narrow part of upstream flume and low shear stress at the wide part of downstream flume. Biostabilization and transport characteristics of the biofilm coated sediment (bio-sediment) were strongly influenced by the cultivation period, and the results were compared with clean sediment. The bio-sediment was more resistant to erosion, and the mean shear stress was increased by factors of 2.65, 2.73 and 5.01 for sediment with 5, 10 and 15 days of biofilm growth compared with clean sediment, resulting in less sediment being eroded from the bed. Simultaneously, the settling velocity was smaller for bio-sediment due to higher organic content and porosity (i.e., lower density). Additionally, there was a smaller probability of deposition for sediment with a longer cultivation period after erosion, resulting in more retention time in aquatic systems. These results will benefit water management in natural rivers.
authors.affiliation: Department of Hydraulic Engineering, State Key Laboratory of Hydro-science and Engineering, Tsinghua University, Beijing, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Fang
authors.affiliation: Department of Hydraulic Engineering, State Key Laboratory of Hydro-science and Engineering, Tsinghua University, Beijing, China.|Department of Civil Engineering, Yasouj University, Yasouj, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Fazeli
authors.affiliation: Department of Hydraulic Engineering, State Key Laboratory of Hydro-science and Engineering, Tsinghua University, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Cheng
authors.affiliation: Department of Hydraulic Engineering, State Key Laboratory of Hydro-science and Engineering, Tsinghua University, Beijing, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.affiliation: School of Environment, Tsinghua University, Beijing, China.
authors.forename: Hongying
authors.initials: H
authors.lastname: Hu
mesh_terms: D000327:Adsorption; D018441:Biofilms; D002681:China; D004784:Environmental Monitoring / Q000379:methods; D019015:Geologic Sediments / Q000032:analysis*; D057446:Hydrodynamics; D008855:Microscopy, Electron, Scanning; D045483:Rivers; D033081:Shear Strength; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014871:Water Microbiology; D014872:Water Movements; D014881:Water Supply