Measurements of Erosion Rate of Undisturbed Sediment under Different Hydrodynamic Conditions in Lake Taihu, China
Yiping Li1,2, Ying Wang1,6, Chunyan Tang2, Desmond Ofosu Anim2,5, Lixiao Ni1,2, Zhongbo Yu3, Kumud Acharya4
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1Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes Ministry of Education,
Hohai University, Nanjing 210098, China
2College of the Environment, Hohai University, Nanjing 210098, China
3State Key Laboratory of Hydrology Water Resources and Hydraulic Engineering,
Hohai University, Nanjing 210098, China
4Division of Hydrologic Sciences, Desert Research Institute, Las Vegas, NV, 89119, USA
5College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
6Fujian Provincial Investigation, Design and Hydropower, Fuzhou 350001, China
Pol. J. Environ. Stud. 2014;23(4):1235–1244
Sediment erosion and nutrient release play a significant role on the degradation of water quality and eutrophication in large shallow lakes. Lake Taihu, the third largest freshwater lake in China, is suffering severe eutrophication and internal nutrient release. In this paper, sediment cores were sampled in different lake regions to determine sediment properties (e.g. particle size and bulk density), nutrient concentrations in the sediment, etc. Flume experiments were developed to examine the sediment erosion rate by using the undisturbed sediment cores under different hydrodynamic conditions in Lake Taihu. The results showed that the sediment properties exhibited great spatial heterogeneity. Particle sizes decreased with increasing depth of sediment thickness. Sediment bulk density increased with sediment depth. TN concentration increased with sediment depth, while TP concentration didn’t show a similar trend in different sampling sites. Erosion rate is a function of particle size, bulk density, and shear stress. It decreased with increasing sediment depth and decreasing flow velocity. The erosion depth in this study was less than 1cm under the flow velocity of 5 to 30 cm/s, indicating that unidirectional flows have little impact on sediment erosion in Lake Taihu.