Parametric uncertainty and sensitivity analysis of hydrodynamic processes for a large shallow freshwater lake |
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| Authors: | Yiping Li Chunyan Tang Jianting Zhu Baozhu Pan Desmond O. Anim Yong Ji |
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| Affiliation: | 1. Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes Ministry of Education, Hohai University, Nanjing 210098, China;2. College of Environment, Hohai University, Nanjing 210098, Chinaliyiping@hhu.edu.cn;4. College of Environment, Hohai University, Nanjing 210098, China;5. Department of Civil and Architectural Engineering, University of Wyoming, Wyoming 82071, USA;6. Changjiang River Scientific Research Institute, Wuhan 430010, China;7. School of Hydraulic and Ecological Engineering, Nanchang Institute of Technology, Nanchang 330099, China |
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| Abstract: | AbstractA parametric uncertainty and sensitivity analysis of hydrodynamic processes was conducted for a large shallow freshwater lake, Lake Taihu, China. Ten commonly used parameters in five groups were considered including: air–water interface factor, water–sediment interface factor, surrounding terrain factor, turbulent diffusion parameters and turbulent intensity parameters. Latin hypercube sampling (LHS) was used for sampling the parametric combinations, which gave predictive uncertainty results directly without using surrogate models, and the impacts of different parametric distribution functions on the results were investigated. The results showed that the different parametric distribution functions (e.g. uniform, normal, lognormal and triangular) for sampling had very little impact on the uncertainty and sensitivity analysis of the lake hydrodynamic model. The air–water interface factor (wind drag coefficient) and surrounding terrain factor (wind shelter coefficient) had the greatest influence on the spatial distribution of lake hydrodynamic processes, especially in semi-closed bays and lake regions with complex topography, accounting for about 60–70% and 20%, respectively, of the uncertainty on the results. Vertically, velocity in the surface layer was also largely influenced by the two factors, followed by velocity in the bottom layer; the middle velocity had minimal impact. Likewise, the water–sediment interface factor (i.e. bottom roughness height) ranked third, contributing about 10% to the uncertainty of the hydrodynamic processes of the lake. In contrast, turbulent diffusion parameters and turbulent intensity parameters in the lake hydrodynamic model had little effect on the uncertainty of simulated results (less than 1% contribution). The findings were sufficiently significant to reduce the parameter uncertainties and calibration workload of the hydrodynamic model in large shallow lakes. Editor Z. W. Kundzewicz; Associate editor S. Grimaldi |
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| Keywords: | EFDC (Environmental Fluid Dynamics Code) model Lake Taihu Latin Hypercube Sampling (LHS) sensitive analysis |
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